Expert consensus on the diagnosis and treatment of germ cell tumors of the mediastinum

Abstract

Abstract: Germ cell tumors of the mediastinum (GCTM) are a type of extragonadal tumor, accounting for <5% of both mediastinal tumors and germ cell tumors. Based on histopathological classification, GCTMs can be divided into three major types: teratomas, seminomatous germ cell tumors, and non-seminomatous germ cell tumors, which can be further subdivided into subtypes such as yolk sac tumors and choriocarcinomas. Due to the scarcity and diversity of GCTMs, there is a lack of clear international standards in diagnosis and treatment, leading to clinical challenges such as high misdiagnosis rates and non-standardized treatment. To promote the standardization of GCTM management, experts from the Pan-Yangtze River Delta Alliance of Research for Thymomas (PRD-ART) conducted panel discussions, integrating the medical evidence in pathology, molecular biology, and new drug development, to create clinical recommendations for diagnosis, treatment, and follow-up. This expert consensus: 1) emphasizes molecular testing in clinical management, 2) encourages multidisciplinary consultation to facilitate personalized therapies, 3) promotes international collaboration to validate novel biomarkers and therapies, and 4) suggests the use of real-world, umbrella trial designs to address the scarcity and heterogeneity problems. These measures aim to standardize and improve the clinical management of GCTMs.

INTRODUCTION

Germ cell tumor of the mediastinum (GCTM) is a rare extragonadal tumor with diverse histopathological subtypes. The lack of clear international diagnosis and treatment standards has led to clinical problems in GCTM such as high misdiagnosis rates and non-standardized treatment. To promote standardized management of GCTMs and provide research directions to address the aforementioned clinical challenges, experts from the Pan-Yangtze River Delta Alliance of Research for Thymomas (PRD-ART) conducted panel discussions, integrating currently available medical evidence from pathology, molecular biology, and new drug development to create clinical recommendations for diagnosis, treatment, and follow-up of GCTM^[1]. This consensus is updated based on our previously released version of consensus, focusing on the diagnosis and treatment of thymic epithelial tumor^[2].

INCIDENCE, ETIOLOGY, AND SCREENING

GCTMs are the most common type of extragonadal germ cell tumor (GCT). Compared to their gonadal counterparts, which occur in the testes or ovaries, GCTMs are rarer, constituting only about 4% of mediastinal tumors and approximately 3% of all GCTs^[3]. GCTMs primarily occur in the anterior mediastinum, with very rare cases reported in the middle and posterior mediastinum^[4,5]. In general, GCTMs are predominantly benign (about 80%-85%), with a roughly equal male-to-female ratio^[6]. In contrast, malignant GCTMs occur more frequently in males, with a male-to-female ratio of as high as 9:1^[7]. While extragonadal GCTs in adolescents also show a male predominance, pediatric extragonadal GCTs are relatively more common in female patients^[8]. The rarity of GCTMs means most clinical studies are limited to single-center and retrospective settings, which makes it difficult to perform a large-scale systematic analysis to support clinical decisions.

GCTMs are considered to arise from the erroneous retention of germ cells in the mediastinal position as they migrate along the midline during embryogenesis^[9,10]. In fact, the vast majority of extragonadal GCTs occur in the midline, such as the mediastinum and retroperitoneum. Similar to GCTs, GCTMs can be divided into three major types according to histopathological typing: teratoma, seminomatous germ cell tumor (SGCT), and non-seminomatous germ cell tumor (NSGCT). Among them, teratoma is the most common type, accounting for approximately 60%-70% in GCTMs. Depending on whether the tumor contains typical immature components during fetal development, teratomas can be further divided into mature teratoma and immature subtypes, most of which are benign tumors^[7]. Unlike teratomas, both SGCTs and NSGCTs are malignant tumors. Based on the latest fifth edition of the World Health Organization classification^[11], NSGCTs can be subdivided into embryonal carcinoma, yolk sac tumor (YST), choriocarcinoma, and mixed GCT according to their histopathological morphology. Two independent subtypes, teratoma with somatic-type malignancies and GCT with associated hematological malignancy, are also described in the classification. There is a certain correlation between the GCTM subtype and the age of onset. As reported in previous studies, the median ages of onset for mediastinal SGCT and mediastinal NSGCT were 33 and 28 years, respectively^[12]. In contrast, the peak ages of onset for pediatric patients were infancy and after 10 years of age^[8]. It was also pointed out in a study that prepubertal patients primarily have mediastinal teratoma and YST, while the vast majority of postpubertal female patients have mediastinal teratoma^[13]. As there is a high misdiagnosis rate due to the variety of GCTM subtypes, they are easily confused with other tumors such as thymoma and lymphoma.

Beyond the issues of case scarcity and subtype diversity, the concomitant diseases also complicate the diagnosis and treatment of GCTMs. Concomitant diseases like chromosomal abnormalities and hematological malignancies are common in GCTM patients. Statistics showed that about 16% of GCTM patients had trisomy 8, and 14% had Klinefelter syndrome^[14]. Approximately 6% of patients with mediastinal NSGCT had leukemia, of which acute megakaryoblastic leukemia (AML-M7) was the most common^[15-20]. Regarding the cause of concomitant leukemia for GCTMs, it is widely believed that the hematological malignancies are not treatment-induced secondary tumors but rather originate from a common clonal origin. Although treatment with topoisomerase II inhibitors is known to potentially induce hematological malignancies^[21,22], cytogenetic analyses indicate that GCTM and acute myeloid leukemia generally share common driver mutations and cellular morphology^[23-25], supporting the notion that both cancers share a common cell origin.

Consensus 1: GCTM is the most common extragonadal GCT, characterized by its scarcity, subtype diversity, and high rate of concomitant diseases. Clinical diagnosis should be performed carefully to avoid misdiagnosis or missed diagnosis. (Recommended)

DIAGNOSIS

Clinical diagnosis

Most GCTMs are accidentally detected by imaging examinations. Patients may be either asymptomatic or symptomatic, with common symptoms such as chest pain, cough, dyspnea, fever, night sweats, and weight loss^[26]. A mediastinal mass has various possible etiologies; besides GCTs, it could be other tumors like thymic tumors, lymphoma, or metastatic carcinoma, or non-neoplastic diseases such as thyroid goiter, thymic cysts, or aortic aneurysms. Because treatment differs, all mediastinal masses should undergo a comprehensive evaluation process, which typically includes imaging, laboratory/molecular tests, and histopathological assessment, to guide treatment decisions [Figure 1].

Figure 1.Flowchart of the diagnostic workflow of GCTM.The flowchart delineates the clinical pathway from initial radiological suspicion to definitive histopathological diagnosis and risk-stratified management. The decision node between primary resection and biopsy depends on the patient’s biochemical profile and anatomical risk. GCT: Germ cell tumor; CT/MRI: computed tomography/magnetic resonance imaging; AFP: alpha-fetoprotein; hCG: β-human chorionic gonadotropin; LDH: lactate dehydrogenase; PET-CT: positron emission tomography-computed tomography; IHC: immunohistochemistry; CK: cytokeratin; GPC3: glypican-3; SALL4: spalt-like transcription factor; i(12p): isochromosome 12p; FISH/RT-PCR: fluorescence in situ hybridization/reverse transcription-polymerase chain reaction; SGCT: seminomatous germ cell tumor; YST: yolk sac tumor; GCTM: germ cell tumor of the mediastinum.

Imaging diagnosis

For mediastinal nodules found in physical examination, especially asymptomatic, small anterior mediastinal nodules less than 3 cm in diameter, benign cysts are the main form, and most of the nodules remain unchanged during follow-up^[27]. To avoid unnecessary surgery, it is recommended to determine the type of a nodule based on the imaging characteristics of contrast-enhanced chest computed tomography (CT) and magnetic resonance imaging (MRI). Serum biomarker tests can be used to supplement to the diagnosis of suspected cases. Patients considered to have benign tumors should undergo regular follow-up to observe changes in the nodules.

Contrast-enhanced chest CT is the main imaging modality for evaluating mediastinal tumors. It can reveal the tumor’s morphology, blood supply, and relationship to surrounding vasculature^[28]. Three-dimensional reconstruction can be performed if necessary. For suspected vascular tumors or mediastinal tumors that invade or compress major vessels, angiography can be used for further evaluation^[7,29]. Additionally, MRI can reveal the relevant characteristics of the lesion by showing its morphology, border, cystic or solid nature, relationship with adjacent tissues/organs, and etc., which helps differentiate thymic hyperplasia, cysts, and malignant thymic neoplasms. For patients with contraindications to iodine-based contrast agents, MRI can serve as an alternative method for assessing mediastinal tumors^[7,29]. Positron emission tomography-CT (PET-CT) can be used for systemic evaluation in patients with mediastinal tumors, helping to determine the presence of recurrent or metastatic lesions. It is also a relatively effective tool for staging and assessing treatment response^[30,31]. One study indicated that PET-CT also has utility in assisting with the differential diagnosis of benign versus malignant lesions and in distinguishing between mediastinal SGCT and NSGCT^[32].

Consensus 2: Patients with mediastinal tumors found by physical examination or by accident are recommended to routinely receive contrast-enhanced chest CT/MRI scans and serum biomarker tests. If a tumor is assessed as benign, a CT/MRI re-examination is recommended to be performed after 3-6 months, and once every 1-2 years thereafter. Patients with suspected malignancies, abnormal serum biomarkers, and/or symptoms are recommended to receive the tissue biopsy as soon as possible to clarify the nature of the lesion. PET-CT may be considered for patients with mediastinal tumors that are difficult to accurately assess by conventional CT/MRI, or those who need a systemic examination and assessment. (Strongly recommended)

All male patients with suspected GCTMs should undergo testicular ultrasonography to rule out a primary gonadal tumor^[7]. Similarly, ovarian ultrasonography should be performed in suspected female patients. Some tumors may lead to inspiratory flow limitation, so pulmonary function tests are required for patients scheduled for surgery. If necessary, additional cardiopulmonary exercise testing may also be performed with reference to the preoperative assessment of lung surgery^[33]. For tumors suspected to originate from other sites, corresponding imaging examinations should be performed, for example, radioactive iodine scanning to assess activity in an intrathoracic goiter and a ^99mTc-isotope scan for a possible retrosternal parathyroid adenoma^[7].

Consensus 3: Any suspected GCTM should undergo adequate clinical and imaging examination to exclude the possibility of mediastinal metastasis from gonadal or retroperitoneal tumors or metastatic carcinoma from non-mediastinal primary sites. For tumors suspected to originate from other origins, specific imaging examinations of the relevant tissues and organs are routinely recommended. (Strongly recommended)

LABORATORY TESTS

In terms of laboratory tests, all patients with mediastinal tumors should undergo routine blood tests^[7]. Patients with suspected GCTMs are recommended to undergo testing for at least 3 serum biomarkers, i.e., alpha-fetoprotein (AFP), β-human chorionic gonadotropin (hCG), and lactate dehydrogenase (LDH). Among them, positive AFP and hCG results represent a high probability of malignant NSGCTs, while a significant elevation of LDH indicates the possibility of lymphoma^[34]. Specifically, in the context of a characteristic mediastinal mass, significantly elevated AFP or HCG typically guides the treatment approach towards systemic therapy or resection without preoperative biopsy. In contrast, marker-negative cases or those with a high surgical risk should prioritize image-guided biopsy to rule out lymphoma or other malignancies. For tumors suspected to originate from other sites, corresponding biomarkers should be tested to aid diagnosis. For example, for suspected thyroid diseases, thyroid function and cortisol should be tested; for suspected thymic epithelial tumors, CYFRA 21-1 and CA125 should be tested; for suspected thymoma with myasthenia gravis, antibody tests for acetylcholine receptor, muscle-specific kinase, and lipoprotein receptor-related protein 4 should be performed^[35-37]. Additionally, for suspected mediastinal tuberculosis, the T-spot test can be performed. For suspected mediastinal infections, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) tests can also be performed.

Consensus 4: Routine blood tests should be performed to aid in the differential diagnosis of patients with suspected GCTMs. Among them, the serum biomarkers to be tested should at least include AFP, hCG, and LDH. For tumors suspected to originate from other origins, specific tumor marker tests on the relevant tissues and organs are routinely recommended to be performed. (Strongly recommended)

Pathological and molecular diagnosis

Although most of the mediastinal diseases are benign, there is still a possibility of a variety of malignant diseases, especially in patients who have already developed symptoms. Therefore, all mediastinal masses where the possibility of malignancy cannot be excluded should be subject to tissue biopsy. It is useful in obtaining tumor samples to determine the nature of the lesion through pathological examination. Options for diagnostic tissue biopsy include transdermal core needle biopsy, transbronchial needle aspiration, mediastinoscopy, mediastinotomy, and thoracoscopic surgery^[38]. For patients with suspected lymphoma, surgery is not routinely preferred due to the significant tumor heterogeneity, and tissue biopsy is an indispensable diagnostic method^[39]. When lymphoma is suspected, image-guided core needle biopsy with multiple passes is the preferred initial approach over fine-needle aspiration to ensure adequate tissue for IHC and flow cytometry. However, for resectable lesions that are highly suspected to be thymoma based on clinical manifestations and imaging features, biopsy should be avoided due to the risk of tumor capsule disruption and potential seeding. Sufficient tissue specimens for pathological and molecular examinations should be obtained in a single biopsy attempt. Additionally, all patients with confirmed GCTMs should undergo karyotype analysis to determine the presence of concomitant genetic syndromes^[40].

Consensus 5: Patients with mediastinal tumors where the possibility of malignancy cannot be excluded by typical imaging features and serum biomarkers are routinely recommended to receive tissue biopsy to carefully determine the nature of the lesion through pathological examination. An appropriate biopsy method should be selected based on the needs, and sufficient tissue specimens required for pathological examination and molecular testing should be obtained in a single biopsy attempt. If a CT-guided biopsy is performed, specimens containing necrotic margins should be adequately sampled. (Strongly recommended)

Consensus 6: Patients with pathologically confirmed GCTMs should be subjected to karyotype analysis to determine the presence of concomitant genetic syndromes. (Strongly recommended)

Different subtypes of GCTMs exhibit distinct pathological and molecular characteristics that facilitate their specific classification^[41]. Special attention should be taken for mixed GCTM, as non-teratomatous components may regress after neoadjuvant therapy, potentially inducing "growing teratoma syndrome", where the residual teratoma overgrows^[42]. Therefore, it is necessary to collect sufficient samples during the pathological examination, carefully observe for the existence of other GCT components, and make the judgment in combination with treatment history to exclude the possibility of mixed GCTMs.

Consensus 7: Any suspected GCTM should be adequately sampled, and the possibility of mixed GCTM should be carefully judged in combination with the treatment history. (Strongly recommended)

In the differential diagnosis, the emphasis on evidence of pathology, immunohistochemistry (IHC), and molecular detection varies with different subtypes of GCTMs. For mediastinal teratoma, since there are no specifically elevated serum biomarkers, the differential diagnosis mainly depends on tissue biopsy and pathological examination. Histologically, mature mediastinal teratoma is manifested as phenotypically well-differentiated tissues deriving from one of the three germinal layers (e.g., skin with skin appendages, teeth or bone, and cartilage), with components such as keratinized or non-keratinized squamous epithelium, skin appendages (e.g., hair, sweat glands, and sebaceous glands), respiratory epithelium, fat, and cartilage commonly observed, and a high incidence of pancreatic tissues^[43]. Other lesions that need to be differentiated from mediastinal teratomas include multilocular thymic cysts^[44] and somatic-type malignant tumors^[45]. The former shows xanthogranulomatous inflammation and myofibroblastic inflammation, while the latter often presents as well-circumscribed nodules with significant cellular atypia and invasive growth.

Compared to benign mediastinal teratoma, organoid morphology is less common, while cellular atypia is more common in malignant mediastinal teratoma. A study on 34 cases of GCTMs provided some pathological characteristics that could aid in the diagnosis of benign or malignant mediastinal teratoma^[46]: (1) Compared to benign teratoma, organoid structures were relatively rare in malignant teratoma (83% vs. 27%), with no pancreatic differentiation; (2) The incidence of glial tissue was also higher in malignant teratoma (11% vs. 63%); (3) If cartilage was present, it could be used to assess less obvious atypia in the epithelium, where malignant tumors feature frequent multinucleation, proliferation, and apoptosis. Additionally, comparative genomic hybridization techniques can also assist in the differential diagnosis of mediastinal GCTs. Mature teratomas have a normal genetic profile with no 12p abnormalities^[47], whereas malignant mediastinal GCTs often exhibit gains/losses of chromosomal arms^[48]. For malignant GCTM patients under 8 years old, their genomic features are more similar to those of testicular GCTs of the same age. Common genomic variations observed include gains of 1q, 3, and 20q, as well as losses of 1p, 4q, and 6q. Conversely, adolescent and adult patients commonly show gains of 12p. Other reported genome variations include loss of chromosome 13 and gain of chromosome 21/X^[47]. Universal thresholds for genomic variations such as i(12p) have not yet been standardized for mediastinal GCTs.

Consensus 8: Any suspected mediastinal teratoma found in pathological examination should be adequately sampled and determined for the benign or malignant nature in combination with treatment history, and be subjected to differential diagnosis with multilocular thymic cysts and somatic-type malignant tumors to avoid misdiagnosis. Although the differential diagnosis of mediastinal teratomas is primarily based on pathological morphology, IHC is routinely recommended as an adjunctive test to prevent missing occult components. For immature mediastinal teratoma with uncertain differential diagnosis, supplemental 12p fluorescence in situ hybridization (FISH) or reverse transcription-polymerase chain reaction (RT-PCR) testing can be considered to assist in determining germ cell origin. (Strongly recommended)

Mediastinal SGCTs should be subjected to differential diagnosis with other GCTMs or mediastinal tumors such as thymic epithelial tumors, mediastinal B-cell lymphomas, and metastatic melanomas through histomorphology and IHC. Particularly, metastatic SGCTs from the testis are prone to misdiagnosis due to similar features. The possibility of primary testicular seminoma should be excluded based on clinical history, physical examination, and imaging features^[49]. Tumor cells of mediastinal SGCTs are arranged in sheets or nested form, with a homogeneous cell morphology, and are characterized by unique fibrovascular septa and lymphocytic infiltration. It is worth noting that inflammation can mask tumor cells. Additionally, scattered multinucleated syncytiotrophoblast cells may also appear in mediastinal SGCTs, so choriocarcinoma should not be diagnosed unless mononuclear cytotrophoblast cells are present. Unlike thymic carcinoma, mediastinal SGCT presents as discrete epithelioid cells that express CD117 in IHC^[43]. Mediastinal SGCTs with positive CAM5.2 are prone to being misdiagnosed as carcinoma, so differential diagnosis is required in combination with OCT3/4 and 12p tests^[50]. Besides IHC, some molecular characteristics are also considered valuable for the auxiliary diagnosis of mediastinal SGCTs. A retrospective study found that TP53 mutations occurred only in mediastinal NSGCTs but not in mediastinal SGCTs (72.2% vs. 0%)^[51]. Two other studies pointed out that there were differences in frequencies of p53 expression (31% vs. 77%), KIT exon 17 mutations (50% vs. 0%), and KRAS mutations (8% vs. 15%) between mediastinal SGCTs and testicular SGCTs, suggesting that they could assist in the differentiation of primary and metastatic SGCTs^[52,53].

Consensus 9: Mediastinal SGCTs should be subjected to differential diagnosis with other GCTMs or mediastinal tumors through histomorphology and IHC, and at least 3 biomarkers: CD117, OCT3/4, and SOX2 (negative) should be tested. Meanwhile, the possibility of primary testicular seminoma should be excluded based on clinical history, physical examination, and imaging features. If necessary, additional genetic testing may be performed to assist in the diagnosis. (Strongly recommended)

YSTs exhibit diverse morphologies. Common patterns include reticular, myxomatous, endodermal sinus, polyvesicular-vitelline, and solid, while rarer patterns include hepatoid, spindle cell, enteric, and endometrioid. IHC is a crucial method for the differential diagnosis of YSTs. Co-expression of AFP, glypican-3 (GPC3), and spalt-like transcription factor 4 (SALL4) can help differentiate YSTs from metastatic carcinoma^[54]. However, due to the lack of specificity of the above biomarkers, a comprehensive diagnosis is still needed based on pathological morphology, clinical factors, and imaging features, such as identifying typical YST areas like Schiller-Duval bodies. Other tumor subtypes that are easily confused and require differential diagnosis include: primary thymic carcinoma, which can be differentiated by positive CD5; seminoma, which can be differentiated by positive OCT3/4, CD117, and D2-40, and by negative GPC3^[45]; embryonal carcinoma, which can be differentiated by positive CD30 and OCT3/4, and cell atypia; sarcoma, which can be differentiated by negative keratin staining and positive staining of mesenchymal markers; multilocular thymic cyst, which can be differentiated by the absence of YST cells^[41]. It is important to note that YSTs may contain focal syncytiotrophoblast cells, which should not be over-interpreted as choriocarcinoma.

Embryonal carcinomas are solid, adenoid, or papillary in arrangement, with significant cellular atypia, and are accompanied by extensive necrosis. They should be carefully differentiated from other GCTs and malignant tumors. Compared with SGCTs, embryonal carcinoma exhibits more cellular atypia and more blurred cell borders, often with common positive CD30^[41]. Compared with YSTs, embryonal carcinoma shows a relatively greater degree of cellular atypia, but typical PAS-positive hyaline bodies (a characteristic of YST) can still be observed in some pediatric cases^[34]. Similar to choriocarcinoma, embryonal carcinoma shows large syncytial cells^[55] and an appliqué pattern of degenerative change at the periphery of nests^[9]. Compared with thymic carcinoma or other metastatic carcinomas, although the cellular atypia is similar, IHC can effectively assist in the differential diagnosis^[41]. Finally, compared to other hematological malignancies such as anaplastic large-cell lymphoma, both CD30 and epithelial membrane antigen (EMA) can be positive, so epithelial structures such as glandular or papillary morphology should be carefully observed for differential diagnosis^[41].

For choriocarcinoma, a “biphasic cell” population of syncytiotrophoblast cells and cytotrophoblast cells, together with the villous-like spatial configuration formed by multinucleated cells surrounding mononuclear cells, is its key characteristic. It can be easily confused with pleomorphic carcinoma of the lung, as both exhibit multinucleated and syncytial cells, with the production of hCG. Characteristics such as multiple tumor masses invading the lung, a second population of cytotrophoblast cells, and a younger age of onset are helpful in diagnosing choriocarcinoma^[56]. Additionally, characteristics such as the absence of significant atypia, a biphasic cell population, and hCG staining are necessary for differentiation from thymic carcinoma.

Consensus 10: The diagnosis of mediastinal NSGCTs should be based on the comprehensive consideration of IHC and histomorphology, clinical factors, and imaging features, and differential diagnosis should be performed with other GCTs, malignant tumors, or metastatic carcinoma. For YSTs, at least 3 biomarkers: AFP, GPC3, and SALL4, should be tested; for embryonal carcinoma, at least 3 biomarkers: CD30, OCT3/4, and SOX2, should be tested; for choriocarcinoma, at least hCG should be tested; if necessary, tests for other markers should be added. (Strongly recommended)

Common genetic variations in GCTM include mutations or deletions of TP53, activating mutations of KRAS/NRAS, loss of PTEN, and etc.^[57]. These variations may be helpful for the differential diagnosis of subtypes and primary sites of GCT. Among them, common gene mutations in mediastinal NSGCT include: TP53 (46%), KIT (18%), KRAS (18%), PTEN (11%), NRAS (4%), and PIK3CA (4%)^[58,59]. Compared with testicular GCT and SGCT (both gonadal and extragonadal), mediastinal NSGCT has a higher frequency of mutations in TP53, PIK3CA pathways (e.g., PTEN, PIK3CA), and cell cycle-related genes (e.g., CCND1/2/3, CDK4/6, CDKN2A/B, RB1), while the frequency of gene mutations in RAS-RAF (e.g., KRAS, NRAS), RTK (e.g., KIT), and DNA damage response (e.g., BRCA1/2, ATM, CHEK2, MUTYH) pathways does not differ significantly^[58,60].

Teratoma with somatic-type malignancies refers to GCT containing non-germ cell-derived malignant components such as sarcoma or carcinoma. Common sarcomas include rhabdomyosarcoma and angiosarcoma. There are also case reports of colon adenocarcinoma, glioblastoma, melanoma, carcinoid, neuroendocrine carcinoma, and other concomitant cancers^[41]. Although these cells retain their respective morphology and phenotype, their mutational and methylation profiles are close to those of GCT^[61,62] and differ significantly from the molecular characteristics of the primary tumor^[63]. The concomitant somatic-type malignancies generally retain chromosome 12p aberrations^[64,65], which is a key factor in distinguishing teratoma with somatic-type malignancies from metastatic cancer. Furthermore, for adenocarcinoma components that are easily confused with embryonal carcinoma, IHC for embryonal carcinoma-specific CD30 and OCT3/4 may aid in differential diagnosis^[66].

Consensus 11: Teratoma with somatic-type malignancies should be differentiated from metastatic carcinoma through 12p FISH/RT-PCR testing. If any adenocarcinoma component is detected, IHC for CD30 and OCT3/4 is recommended to differentiate from embryonal carcinoma. (Strongly recommended)

For GCT with associated hematological malignancy, differential diagnosis should be mainly performed with chemotherapy-related hematological malignancies^[17]. The former has a clonal isochromosome 12p [i(12p)], and the hematological malignancy typically appears earlier, with a median time of only 4.8 months^[67], whereas chemotherapy-related hematological malignancies typically occur 25-60 months after chemotherapy^[45].

Consensus 12: GCT with associated hematological malignancy should be differentiated from chemotherapy-related hematological malignancies through 12p FISH/RT-PCR testing and considering the time of onset. (Strongly recommended)

Tables 1 and 2 outline the IHC and molecular markers useful for the differential diagnosis of GCTM, respectively^[60,68]. IHC markers specific to lymphoma (e.g., CD30) and epithelial cells [e.g., Cytokeratin (CK)] can be used to rule out tumors of other origin. Stem cell markers such as NANOG, OCT3/4, SALL4, and SOX2 are crucial for the differential diagnosis of GCT subtypes. Specifically, SGCT generally expresses KIT and OCT3/4, but SOX2 is negative; YST generally expresses AFP, GPC3, and SALL4; Embryonal carcinoma generally expresses OCT3/4 and SOX2; hCG is specifically expressed in choriocarcinoma^[41,60,68]. To accurately diagnose the subtypes of GCTM, a combination of pathological morphology and at least 3 IHC markers is required to obtain a reliable diagnosis^[68]. Furthermore, novel biomarkers have been confirmed to have been confirmed to have value in the diagnosis of specific subtypes of GCT, such as glial cell line-derived neurotropic factor receptor alpha-1 (GFRA-1) specifically expressed in immature teratoma^[69], CAM5.2 positive in mediastinal SGCT but not in testicular SGCT^[70], LIN28 positive in SGCT and YST but negative in teratoma^[71], and HNF1-β and ZBTB16 specifically expressed in YST^[72,73].

Table 1.IHC markers for GCTM subtyping

	Teratoma	SGCT	YST	Embryonal carcinoma	Choriocarcinoma
AFP		Negative	Positive	Negative	Negative
CD117(c-kit)	Negative	Positive	Negative	Negative	Negative
CD30	Negative	Negative	Negative	Positive	Negative
CK	Positive	Positive(dot-like)	Positive	Positive	Positive
EMA	Positive
GPC3		Negative	Positive	Negative
hCG			Negative	Negative	Positive
NANOG	Negative	Positive	Negative	Positive	Negative
OCT3/4	Negative	Positive	Negative	Positive	Negative
PLAP		Positive			Negative
SALL4	Positive	Positive	Positive	Positive	Positive
SOX2		Negative	Negative	Positive	Negative

Table 2.Molecular markers of different GCTM subtypes

Differential diagnosis	12p aberrations	(1) 12p aberrations are prevalent in malignant GCT (except for pediatric GCT) and can be used to differentiate other non-GCT mediastinal tumors(2) Teratoma with somatic-type malignancies generally retains 12p aberrations, which can be used to differentiate metastatic cancer(3) GCT with associated hematological malignancies generally retains 12p aberrations, which can be used to differentiate chemotherapy-related hematological malignancies
	Genomic variations	Increases in 1q, 3, and 20q and decreases in 1p, 4q, and 6q are common in pediatric patients < 8 years old and can be used to differentiate pediatric GCT
	TP53 mutations	(1) TP53 mutations only occur in mediastinal NSGCT but not in mediastinal SGCT, and can be used to differentiate mediastinal NSGCT and SGCT.(2) Within GCTM subtypes, TP53 mutations are more common in mediastinal NSGCT and mediastinal GCT with associated hematological malignancies.
	Mutation frequency	(1) There is a difference in the mutation frequency of p53 expression (31% vs. 77%), KIT exon 17 mutations (50% vs. 0%), and KRAS mutations (8% vs. 15%) between mediastinal SGCT and testicular SGCT, which can be used to differentiate metastatic gonadal tumors(2) Compared to testicular GCT and SGCT, mediastinal NSGCT has a higher mutation frequency in TP53, PIK3CA pathways (e.g., PTEN, PIK3CA), and cell cycle-related genes (e.g., CCND1/2/3, CDK4/6, CDKN2A/B, RB1), which can be used to differentiate mediastinal NSGCT
Predicting platinum resistance	TP53 mutations	TP53 mutations play an important role in cisplatin resistance of GCT cells
	MYCN amplification	MYCN amplification is another potential factor in chemotherapy resistance
	miRNA	miRNA expression profiling can effectively identify cisplatin-resistant cell strains
Guiding treatment options	DDR gene mutations	Predicts radiotherapy response
	NRAS mutations	Predicts MEK inhibitor response
	RET amplification	Predicts sunitinib response
	TMB	Mediastinal NSGCT has a relatively higher incidence of high TMB, which may be a potential biomarker for predicting the efficacy of immunotherapy
Disease monitoring	miRNA	miR-371-373 and miR-302 clusters are widely expressed in malignant GCTs and may be used for dynamic monitoring of tumor burden and recurrence
Prognostic evaluation	TP53 mutations	TP53 mutation carriers have significantly shorter survival

Consensus 13: IHC is important for determining the pathological subtypes of GCTMs. All patients with suspected GCTMs are recommended to be tested for AFP, CD117, CK, GPC3, hCG, OCT3/4, SALL4, and SOX2. When the differential diagnosis is still uncertain, testing of relevant novel biomarkers may be considered. (Strongly recommended)

Molecular testing is also a key to differential diagnosis of GCTM. Chromosome 12p abnormalities, such as i(12p) or increased 12p copy number, are classic molecular characteristics of GCT. i(12p) is associated with the strong tumor aggressiveness of GCT. Genes located in the short arm of this chromosome may be associated with the occurrence and development of GCT, including KRAS, Cyclin D2, FGF6, and etc., but the pathogenic mechanism is still unclear^[60]. Except in pediatric and benign GCTs^[74,75], 12p abnormalities are prevalent in malignant GCTs, regardless of subtype^[76,77]. For cases where the origin of germ cells is difficult to determine, additional testing of 12p status may be considered to differentiate mediastinal GCT from other mediastinal tumors such as thymoma and lymphoma, and to differentiate primary mediastinal tumors from metastatic gonadal tumors^[68,78,79].

Consensus 14: For cases where germ cell origin is uncertain, additional 12p FISH/RT-PCR testing should be considered to differentiate mediastinal GCTs from other mediastinal tumors such as thymoma and lymphoma, and to distinguish primary mediastinal tumors from metastatic gonadal tumors. (Strongly recommended)

TREATMENT STRATEGIES

Due to the rarity of GCTM, almost all studies exploring treatment modalities are single-center, retrospective studies, resulting in a lack of consistent treatment standards and limited effective treatment options for high-risk subtypes. Based on the available clinical evidence, our recommended standard treatment modalities for GCTM are shown in Figure 2.

Figure 2.Flowchart of the treatment of GCTM. Brief legend describing key visual indicators or differential diagnostic points shown in the images. SGCT: seminomatous germ cell tumor; NSGCT: non-seminomatous germ cell tumor; BEP: bleomycin + etoposide + cisplatin; VIP: etoposide + ifosfamide + cisplatin; NGS: next-generation sequencing; GCTM: germ cell tumor of the mediastinum.

Benign, pure mature teratomas are insensitive to chemotherapy, thus, surgical resection is required as soon as possible^[80]. Patients with this type of GCTM have an excellent prognosis after complete surgical resection, but there is still a possibility of recurrence, so close follow-up monitoring is necessary^[81]. For high-risk patients found to have postoperative malignant components, adjuvant chemotherapy can be considered.

Consensus 15: Mediastinal teratoma should be treated surgically as soon as possible once diagnosed, because it is difficult to determine whether the teratoma is benign or malignant before surgery, and it has the potential to become malignant and penetrate adjacent tissues. (Strongly recommended)

For other GCTM subtypes, multimodal therapy based on platinum-based chemotherapy and surgery is the current standard of care. The chemotherapy regimen typically consists of 4 cycles of BEP (bleomycin, etoposide, and cisplatin) or VIP (etoposide, ifosfamide, and cisplatin), followed by surgical resection for persistent residual tumor lesions after chemotherapy^[3,80]. SGCTs are highly sensitive to platinum-based chemotherapy, and most patients can achieve a complete response, so platinum-based chemotherapy is the preferred treatment, and surgery can be omitted^[82]. Furthermore, extragonadal SGCTs are also sensitive to radiotherapy^[83]. Radiotherapy is also an option to be considered for patients who are intolerant to chemotherapy.

Consensus 16: For confirmed mediastinal SGCT, platinum-based chemotherapy is preferred. (Strongly recommended)

Patients with NSGCT have a significantly worse prognosis compared to SGCT with an excellent prognosis of up to 70%-100% 5-year overall survival (OS) rate^[84-90]. Because cure is difficult for NSGCT with chemotherapy alone, surgical resection of residual tumor lesions is required to improve patient prognosis^[91,92]. Retrospective multivariate analysis showed that surgical resection was an independent factor for improving the prognosis of mediastinal NSGCT^[93,94]. Any visible residual tumor, even if less than 1 cm, needs to be resected to minimize the risk of recurrence^[95]. Adjuvant chemotherapy may be considered for NSGCT patients with high postoperative risk.

Consensus 17: For confirmed mediastinal NSGCT, platinum-based chemotherapy is preferred, followed by resection of residual tumors. (Strongly recommended)

Regarding the choice of chemotherapy regimen, although studies indicated that the prognosis of patients receiving BEP and VIP regimens is similar^[96], the risk of severe pulmonary complications with BEP chemotherapy is significantly higher^[97-100], therefore, if BEP chemotherapy is selected, patients should be reasonably evaluated for pulmonary toxicity, and the drug should be discontinued promptly when symptoms such as decreased diffusion capacity or respiratory failure occur^[101]. It should be noted that chemotherapy complications are more frequent in elderly patients over 50 years old^[102], and close monitoring is required during treatment. In pediatric cases, treatment strategies must carefully balance oncological efficacy against long - term toxicity. Specifically, it concerns cisplatin - induced ototoxicity and nephrotoxicity, which might require dose adjustments or alternative treatment regimens for younger children. If a patient has concomitant lung disease or pulmonary function impairment, VIP chemotherapy is preferred over BEP chemotherapy^[96]. First-line high-dose chemotherapy (HDCT) shows better efficacy for mediastinal NSGCT compared to the same used in later-line treatment, and thus can be considered for patients with a good performance status^[103,104]. However, the effectiveness of HDCT is still controversial in some studies^[105], so it should be used with caution. Additionally, a single-center study using radiotherapy in the initial treatment of mediastinal NSGCT showed that radiotherapy can significantly reduce the risk of local recurrence and is a treatment option to be considered, but further validation is needed^[106].

Consensus 18: BEP is the preferred chemotherapy regimen, and patients should be closely monitored for pulmonary toxicity during treatment. If a patient has concomitant lung disease or pulmonary function impairment, VIP chemotherapy is preferred over BEP chemotherapy. (Strongly recommended)

Resistance to platinum-based chemotherapy is one of the main causes of failure to standard of care in GCT. It has been suggested that TP53 mutations play an important role in the cisplatin resistance of GCT cells^[107-109]. TP53 mutations are more common in mediastinal NSGCT (56%-72%) and mediastinal GCT with associated hematological malignancies (91%), and mutation carriers have significantly shorter survival^[64,79,110]. MYCN amplification occurs in approximately 5% of platinum-resistant patients and is mutually exclusive with TP53/MDM2 mutations, representing another potential factor contributing to chemotherapy resistance^[51]. A cell experiment revealed that the expression of the miR-371-373 clusters was associated with cisplatin resistance in GCT, suggesting that miRNA detection may help identify patients who are resistant to cisplatin^[111].

Consensus 19: TP53 mutations are a key contributor to resistance to platinum-based chemotherapy in GCTM. Detecting TP53 gene mutations and miRNA expression shows promise to monitor drug resistance in GCTM, but further clinical study validation is still required. (Recommended)

There is currently no effective treatment regimen for patients with refractory or relapsed GCTM. HDCT has shown some efficacy as a second-line palliative treatment for GCT^[112], but is less effective for GCTM^[113,114], and most patients may not be eligible for treatment due to disease progression and poor performance status^[115]. The outcomes of single-agent chemotherapy regimens are also unsatisfying. A single-center study demonstrated that either suramin, all-transretinoic acid, topotecan, pyrazoloacridine, temozolomide, ixabepilone, or sunitinib had extremely limited efficacy in the treatment of refractory or relapsed GCTM^[116]. Genetic testing has certain clinical significance in guiding individualized treatment. Some studies have identified potentially targetable gene variations related to drug resistance in GCT through whole-exome sequencing, including those associated with RTK, RAS, PI3K/mTOR, cell cycle, and other pathways^[51]. Individualized medication targeting these variations is worthy of further clinical exploration. We encourage patients for whom no suitable treatment is available to undergo genetic testing and to actively participate in clinical trials for new drugs.

Consensus 20: There is currently no effective treatment regimen for patients with refractory or relapsed GCTM. Next-generation sequencing for common genetic variations in GCTM subtypes is recommended to explore the possibility of personalized therapy. (Recommended)

Table 3 lists some study data on alternative treatment options for refractory or relapsed GCTM^[117-126]. Chemotherapy regimens such as irinotecan + paclitaxel + oxaliplatin (IPO) and paclitaxel + ifosfamide, followed by carboplatin + etoposide (TI-CE) have shown favorable efficacy^[123,124], but more evidence is still needed to support their clinical use. Based on the theory that high DNA methylation levels contribute to platinum resistance^[127-129], a study investigated the efficacy of the demethylating agent 5-azacitidine as an epigenetic modulator in combination with cisplatin in the treatment for NSGCT. In cell experiments, 5-azacitidine could at least partially restore the sensitivity of GCT cells to cisplatin, which preliminarily validated the feasibility of this treatment regimen^[119]. Another study found that VIRMA, a protein in the methyltransferase complex, led to cisplatin resistance in GCT by interfering with DNA repair and proposed that the m⁶A methyltransferase complex was a potential therapeutic target for platinum-resistant GCT^[130].

Table 3.Summary of treatment strategy studies in refractory or relapsed GCTM

Regimen	Number of patients	Outcome
*Guadecitabine and cisplatin[117]	2 GCTM out of 14 GCT	A mediastinal YST patient receiving forth-line guadecitabine + cisplatin achieved 5-month PFS and 16-month OS
5-Azacitidine and cisplatin[118]	Cell line experiments	Partial restoration of cisplatin sensitivity at nanomolar concentrations
Pembrolizumab[119]	1 GCTM out of 12 GCT	No objective responses were observed
Tivantinib (a MET-TKI)[120]	3 GCTM out of 27 GCT	No objective responses were observed
Oxaliplatin and bevacizumab[121]	5 GCTM out of 29 GCT	ORR: 27.6% including 1 CR; Median DoR: 5 months
Temozolomide[122]	3 GCTM out of 20 GCT	ORR: 10% including 2 PR lasting 9 and 3.5 months; Median TTP: 1.5 months; Median OS: 3.1 months
*TI-CE regimen[123]	21 NSGCTM out of 107 GCT	With a median follow-up of 61 months, five (24%) mediastinal NSGCT patients remain disease-free and six (29%) patients are still alive
*IPO followed by topotecan-based high-dose therapy[124]	5 GCTM out of 28 GCT	ORR: 80% (4/5); Three GCTM patients received HDCT, of whom two are progression-free for 15 and 27 months
Gemcitabine and oxaliplatin[125]	4 GCTM out of 30 GCT	ORR: 46% (16/35); Seven (44%) responses occurred in cisplatin-refractory patients
Irinotecan[126]	3 GCTM out of 15 GCT	No objective responses were observed

Consensus 21: Methylation is a potential mechanism of platinum resistance in GCTs, and the efficacy of second-line treatment of GCTM by demethylating agents or targeting related methyltransferases deserves further investigation. (Recommended)

Biomarker-driven precision therapy is a feasible future direction for the treatment of GCTM. Results of the phase III clinical trial GETUG 13 showed that when AFP and hCG levels did not decline after BEP chemotherapy, switching to a dose-dense chemotherapy regimen significantly improved the 3-year progression-free survival (PFS) rate compared to continuing BEP chemotherapy (59% vs. 48%, hazard ratio = 0.66)^[131]. Regarding the predictive value of IHC for the efficacy of second-line TIP (paclitaxel + ifosfamide + cisplatin) chemotherapy, a phase II single-center prospective study showed that the expressions of ERCC1, topoisomerases 1 and 2A, HER2, and p53 were not effective in predicting the effectiveness of chemotherapy^[132]. Together, these findings suggest that the predictive value for IHC remains unclear, but changes in serum biomarker levels have the potential to guide the individualized chemotherapy for high-risk GCT.

The therapeutic effect of targeted therapy for GCTM is also worth exploring. A genomic study identified numerous potentially druggable alterations in platinum-resistant GCT, including those affecting the TP53/MDM2, Wnt/β-catenin, PI3K, and MAPK signaling pathways^[133]. Although many druggable targets are available, most of them still lack sufficient clinical evidence. A phase II clinical trial demonstrated that imatinib had poor efficacy in treating KIT-expressing metastatic GCT^[134]. Another phase II clinical trial showed that sunitinib was effective in treating refractory or relapsed GCT, and identified RET amplification as a potential predictive biomarker for sunitinib efficacy^[135]. A case report also indicated that a mediastinal YST patient harboring a BRCA2 germline mutation was sensitive to radiotherapy, suggesting that mutations in DNA damage repair genes may be helpful to screen GCTM patients suitable for radiotherapy^[136]. Additionally, a GCTM patient with NRAS somatic mutation and associated leukemia responded to MEK inhibitor therapy^[137]. More novel targeted agents and predictive biomarkers await research and development.

For immunotherapy, immune checkpoint inhibitors such as pembrolizumab have poor efficacy in the treatment of GCT, and the predictive value of PD-L1 expression is questionable. Ongoing trials are exploring combination strategies and the role of the tumor microenvironment in overcoming chemoresistance^[120]. However, in testicular GCT, it has been reported that some patients with KRAS mutations responded to immunotherapy^[138]. Additionally, some studies have shown that microarray testing can select patients who are more likely to respond to immunotherapy^[139], underscoring the need to develop predictive biomarkers for immunotherapy efficacy in GCTM. Currently, no GCTM patients with microsatellite instability high have been reported^[140]. However, it has been suggested that mediastinal NSGCT has a relatively higher incidence of high tumor mutation burden (TMB, ≥ 10 mutations/Mb) compared to testicular NSGCT (11.4% vs. 4.7%), so TMB may be a potential biomarker for predicting immunotherapy efficacy^[58].

Consensus 22: Dynamic changes in serum biomarkers have certain potential for monitoring and guiding personalized chemotherapy for high-risk GCTs. Currently, there is a lack of sufficient clinical evidence to support biomarker-driven targeted therapy, and predictive biomarkers (such as TMB) used to guide immunotherapy still require further clinical trial validation. (Recommended)

Prognosis and surveillance

GCTM has a worse prognosis than GCT occurring in other sites (5-year PFS rate of 35% vs. 77% and 5-year OS rate of 40% vs. 82% for mediastinal NSGCT compared to testicular GCT), and mediastinal SGCT has a better prognosis than mediastinal NSGCT (5-year PFS rate of 80% vs. 35% and 5-year OS rate of 85% vs. 40%)^[10,87]. For pediatric patients, GCTM also has a worse prognosis compared to other sites (5-year OS rate of 49% vs. 89%^[141]), but patients with malignant GCTM have a relatively better prognosis compared to adults, with a 5-year survival rate of approximately 60%^[142]. It should be noted that patients with certain subtypes of GCTM have an extremely poor prognosis. For example, the median cancer-specific survival is only 12 months for choriocarcinoma and embryonal carcinoma^[141], whereas the median survival is only 6 months for GCTM patients with associated hematological malignancies^[17].

Prognostic evaluation is helpful in guiding treatment decision for GCTM. The International Germ Cell Cancer Collaborative Group (IGCCCG) classification is a classic prognostic model for GCT^[143]. For NSGCT, primary mediastinal tumor, elevated AFP/hCG/LDH, and visceral metastasis outside the lung (e.g., liver, bone, brain) are independent factors for poor prognosis. For SGCT, visceral metastasis other than the lung is the main adverse prognostic factor. By combining the aforementioned prognostic factors, GCT patients can be effectively stratified according to prognosis. Subsequent studies have further identified other factors for more precise patient prognosis stratification. A study found that in the IGCCCG poor-prognosis subgroup, patients with primary mediastinal tumors and lung metastases experienced worse outcomes, while patients without visceral metastases had a relatively better prognosis^[144]. Another study also indicated that in IGCCCG high-risk NSGCT, a subset of patients with a better prognosis can be identified based on the presence of an embryonal carcinoma component, high Ki-67 expression, low apoptotic protein levels, and low p53 expression^[145]. For GCTM, Moran and Suster established a staging system based on lesion location and extent of tumor involvement, which can further subdivide the prognosis of patients on the basis of pathological subtypes^[146]. Other reported factors associated with the prognosis of GCTM include age, tumor size, number of metastatic sites, completeness of surgical resection, presence of complete tumor necrosis after chemotherapy, and ratio of neutrophil to lymphocyte^[93,147-151]. For teratomas not covered by IGCCCG, studies have shown that the presence of digestive tract tissue, immature neuroectodermal cells, or somatic malignant transformation suggests a higher tumor aggressiveness^[152-154].

Consensus 23: The IGCCCG classification can be utilized for prognostic stratification of GCT patients, but there remains room for optimization. TP53 mutations, expression of Ki-67, and the ratio of neutrophil to lymphocyte may also contribute to the prognosis of GCTM patients. (Recommended)

Because patients with a history of GCTM are at higher risk of subsequent AML-M7 development^[14] and have a 10% chance of developing metachronous testicular cancer (for male patients) within 10 years^[155], long-term follow-up after treatment is recommended for all GCTM patients. Serum biomarkers such as AFP and hCG are important for post-treatment monitoring and can be used to assess the presence of residual tumor after surgery and the risk of postoperative recurrence^[156]. Nonetheless, these biomarkers perform poorly in identifying residual tumor after chemotherapy^[157]. Studies have found that miR-371-373 and miR-302 clusters are widely expressed in malignant GCTs and are potential biomarkers for dynamic monitoring of tumor burden and recurrence^[158]. A case report has shown that although elevated serum AFP made the differential diagnosis more challenging in a patient with mediastinal NUT carcinoma, miR-371a-3p levels were negative, suggesting a high specificity of this biomarker^[159].

Consensus 24: For mediastinal SGCT with a good prognosis, it is recommended to perform annual CT/MRI examination, testicular/ovarian ultrasound, and serum biomarker testing as follow-up after surgical therapy until 10 years postoperatively. For mediastinal NSGCT with a poor prognosis, it is recommended to perform CT/MRI examinations, testicular/ovarian ultrasound, and serum biomarker testing every 6 months as follow-up within 3 years after surgical therapy, then change to annual re-examination. Special attention should be paid to evaluating the occurrence of hematological malignancies. If necessary, testing of miRNA levels may be considered as a means of monitoring tumor status. (Strongly recommended)

FUTURE PROSPECTS

Guiding personalized treatment through molecular subtyping will be an important direction for precision medicine in GCTM. A comprehensive analysis of genomics, epigenetics, and proteomics can not only further explore the different pathogenesis of GCTM, but also support individualized medication. For example, guiding immunotherapy by differentiating cold and hot tumors based on their immune microenvironment, and validating the efficacy of pan-KRAS inhibitors in KRAS-mutant tumors. Liquid biopsy also holds promise for breaking through the limitations of traditional biomarkers, such as AFP and hCG, and achieving timely treatment of GCTM. For instance, early detection of platinum resistance by TP53 mutations, and dynamic monitoring of tumor burden by circulating tumor DNA or miRNA.

However, in the case of GCTM, the study progress is severely limited by the scarcity of patients and the lack of standardized practices across study sites. To accelerate study progress and the implementation of new drugs, particularly for refractory or relapsed mediastinal NSGCT and pediatric patients, establishing a global collaborative international research consortium may be considered to promote standardized diagnosis and treatment, as well as the conduct of large cross-regional clinical trials. The clinical validation of novel biomarkers and innovative therapies can be conducted through umbrella real-world studies. Considering the clinical complexity of GCTM, we encourage multidisciplinary team discussion to explore the most appropriate treatment strategies by integrating pathological, molecular, imaging, and clinical factors. Patients are encouraged to actively participate in clinical trials to gain access to new drugs. In the future, with the development of molecular diagnosis, real-time monitoring, and international resources, the diagnosis and treatment for GCTM are expected to shift from “empirical chemotherapy” towards “precision intervention”, ultimately improving long-term survival for high-risk patients.

Consensus 25: To promote the development of innovative therapies and predictive biomarkers for GCTM, the construction of international collaborative platforms is encouraged to facilitate the clinical validation of new technologies through umbrella real-world studies. (Recommended)

Consensus 26: Complicated cases are encouraged to undergo molecular-based multidisciplinary consultation to discuss the most appropriate treatment strategy, integrating pathological, molecular, imaging, and clinical factors. (Strongly recommended)

References

1. Xu C, Hao Y, Wang D. ECLUNG consensus/guidelines development principles and methods (2024 edition). Intelligent Pharmacy.. 2025; 3:141-2. DOI
2. Xu C, Zhang Y, Wang W. Chinese expert consensus on the diagnosis and treatment of thymic epithelial tumors. Thorac Cancer.. 2023; 14:1102-17. DOI | PubMed |
3. Rosti G, Secondino S, Necchi A, Fornarini G, Pedrazzoli P. Primary mediastinal germ cell tumors. Semin Oncol.. 2019; 46:107-11. DOI | PubMed
4. Wang L, Zhao J, An T. Clinical characteristics and outcomes of patients with primary mediastinal germ cell tumors: a single-center experience. Front Oncol.. 2020; 10:1137. DOI | PubMed |
5. Safadi S, Timsahi W, Saadoune M, Khayi FE, Daoudi A. Mature teratoma of posterior mediastinum in a newborn: a case report. Cureus.. 2025; 17:e82818. DOI | PubMed |
6. Lewis BD, Hurt RD, Payne WS, Farrow GM, Knapp RH, Muhm JR. Benign teratomas of the mediastinum. The Journal of Thoracic and Cardiovascular Surgery.. 1983; 86:727-31. DOI | PubMed
7. LoCicero J, IIIFeinsteinRHColson YL.
8. Schneider DT, Calaminus G, Koch S. Epidemiologic analysis of 1,442 children and adolescents registered in the German germ cell tumor protocols. Pediatr Blood Cancer.. 2004; 42:169-75. DOI
9. McKenney JK, Heerema-McKenney A, Rouse RV. Extragonadal germ cell tumors: a review with emphasis on pathologic features, clinical prognostic variables, and differential diagnostic considerations. Adv Anat Pathol.. 2007; 14:69-92. DOI | PubMed
10. Stang A, Trabert B, Wentzensen N. Gonadal and extragonadal germ cell tumours in the United States, 1973-2007. Int J Androl.. 2012; 35:616-25. DOI | PubMed |
11. Marx A, Chan JKC, Chalabreysse L. The 2021 WHO classification of tumors of the thymus and mediastinum: what is new in thymic epithelial, germ cell, and mesenchymal tumors? J Thorac Oncol. 2022;17:200-13.DOI
12. Bokemeyer C, Nichols CR, Droz JP. Extragonadal germ cell tumors of the mediastinum and retroperitoneum: results from an international analysis. J Clin Oncol.. 2002; 20:1864-73. DOI
13. Marchevsky AM, Wick MR, EditorsDOI
14. Aguirre D, Nieto K, Lazos M. Extragonadal germ cell tumors are often associated with Klinefelter syndrome. Hum Pathol.. 2006; 37:477-80. DOI | PubMed
15. Hartmann JT, Nichols CR, Droz JP. Hematologic disorders associated with primary mediastinal nonseminomatous germ cell tumors. J Natl Cancer Inst.. 2000; 92:54-61. DOI
16. John S, Muqeet Adnan MA, Khalil MO. Mediastinal germ cell tumor and acute megakaryoblastic leukemia- a systematic review of cases reported in the literature. Blood.. 2014; 124:3694. DOI
17. Nichols CR, Roth BJ, Heerema N, Griep J, Tricot G. Hematologic neoplasia associated with primary mediastinal germ-cell tumors. N Engl J Med.. 1990; 322:1425-9. DOI | PubMed
18. Mihál V, Dusek J, Jarosová M. Mediastinal teratoma and acute megakaryoblastic leukemia. Neoplasma.. 1989; 36:739-47. PubMed
19. DeMent SH, Eggleston JC, Spivak JL. Association between mediastinal germ cell tumors and hematologic malignancies. Report of two cases and review of the literature. Am J Surg Pathol.. 1985; 9:23-30. DOI | PubMed
20. Nichols CR, Hoffman R, Einhorn LH, Williams SD, Wheeler LA, Garnick MB. Hematologic malignancies associated with primary mediastinal germ-cell tumors. Ann Intern Med.. 1985; 102:603-9. DOI | PubMed
21. Felix CA. Secondary leukemias induced by topoisomerase-targeted drugs. Biochim Biophys Acta.. 1998; 1400:233-55. DOI | PubMed
22. Ratain MJ, Rowley JD. Therapy-related acute myeloid leukemia secondary to inhibitors of topoisomerase II: from the bedside to the target genes. Ann Oncol.. 1992; 3:107-11. DOI
23. Orazi A, Neiman RS, Ulbright TM, Heerema NA, John K, Nichols CR. Hematopoietic precursor cells within the yolk sac tumor component are the source of secondary hematopoietic malignancies in patients with mediastinal germ cell tumors. Cancer.. 1993; 71:3873-81. DOI
24. Lu C, Riedell P, Miller CA. A common founding clone with TP53 and PTEN mutations gives rise to a concurrent germ cell tumor and acute megakaryoblastic leukemia. Cold Spring Harb Mol Case Stud.. 2016; 2:a000687. DOI | PubMed |
25. Ladanyi M, Samaniego F, Reuter VE. Cytogenetic and immunohistochemical evidence for the germ cell origin of a subset of acute leukemias associated with mediastinal germ cell tumors. J Natl Cancer Inst.. 1990; 82:221-7. DOI
26. Kang J, Mashaal H, Anjum F.DOI
27. Fang W, Xu N, Shen Y. Management of incidentally detected small anterior mediastinal nodules: Which way to go? Lung Cancer. 2022;168:30-5.DOI
28. Mediastinum and Chest Wall Group of Thoracic Surgeon Branch of Chinese Medical Doctor Association, Thoracic Surgery Committee of Chinese Research Hospital Association, Lung Cancer Prevention Branch of China International Exchange and Promotive Association for Medical and Health Care, et al. 2022 Chinese expert consensus on perioperative and whole-course diagnosis and treatment of mediastinal and chest wall tumors. Chin J Clin Thorac Cardiovascular Surg.. 2023; 30:325-32. DOI
29. Juanpere S, Cañete N, Ortuño P, Martínez S, Sanchez G, Bernado L. A diagnostic approach to the mediastinal masses. Insights Imaging.. 2013; 4:29-52. DOI | PubMed |
30. Friedberg JW, Chengazi V. PET scans in the staging of lymphoma: current status. Oncologist.. 2003; 8:438-47. DOI | PubMed
31. Paes FM, Kalkanis DG, Sideras PA, Serafini AN. FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease. Radiographics.. 2010; 30:269-91. DOI | PubMed
32. Lee K, Kim YI, Oh JS. [18F]fluorodeoxyglucose positron emission tomography/computed tomography characteristics of primary mediastinal germ cell tumors. Sci Rep.. 2023; 13:17619. DOI | PubMed |
33. Colice GL, Shafazand S, Griffin JP, Keenan R, Bolliger CT. ; American College of Chest Physicians. Physiologic evaluation of the patient with lung cancer being considered for resectional surgery: ACCP evidenced-based clinical practice guidelines (2nd edition). Chest.. 2007; 132 Suppl:161S-77S. DOI | PubMed
34. Lack EE, Weinstein HJ, Welch KJ. Mediastinal germ cell tumors in childhood. J Thorac Cardiov Sur.. 1985; 89:826-35. DOI
35. Gilhus NE. Myasthenia gravis. N Engl J Med.. 2016; 375:2570-81. DOI | PubMed
36. Caposole MZ, Aruca-Bustillo V, Mitchell M, Nam B. Benign metachronous bilateral ovarian and mediastinal teratomas with an elevated alpha-fetoprotein. Ann Thorac Surg.. 2015; 99:1073-5. DOI | PubMed
37. Albany C, Einhorn LH. Extragonadal germ cell tumors: clinical presentation and management. Curr Opin Oncol.. 2013; 25:261-5. DOI | PubMed
38. Deng XX, Li ZY, Lin L, Chen Y. Advances in biopsy techniques for mediastinal lesions. Zhonghua Jie He He Hu Xi Za Zhi.. 2025; 48:780-4. DOI | PubMed
39. Carter BW, Marom EM, Detterbeck FC. Approaching the patient with an anterior mediastinal mass: a guide for clinicians. J Thorac Oncol.. 2014; 9 Suppl:S102-9. DOI
40. Faure-Conter C, Orbach D, Fresneau B. Disorder of sex development with germ cell tumors: Which is uncovered first? Pediatr Blood Cancer. 2020;67:e28169.DOI
41. El-Zaatari ZM, Ro JY. Mediastinal germ cell tumors: a review and update on pathologic, clinical, and molecular features. Adv Anat Pathol.. 2021; 28:335-50. DOI | PubMed
42. Sachdeva AK, Penumadu P, Kohli P, Dubashi B, Munuswamy H. Growing teratoma syndrome in primary mediastinal germ cell tumor: our experience. Asian Cardiovasc Thorac Ann.. 2019; 27:98-104. DOI | PubMed
43. Pini GM, Colecchia M. Mediastinal germ cell tumors: a narrative review of their traits and aggressiveness features. Mediastinum.. 2022; 6:5. DOI | PubMed |
44. Rakheja D, Weinberg AG. Multilocular thymic cyst associated with mature mediastinal teratoma: a report of 2 cases. Arch Pathol Lab Med.. 2004; 128:227-8. DOI | PubMed
45. Travis WD, Brambilla E, Burke AP.
46. Kao CS, Bangs CD, Aldrete G, Cherry AM, Ulbright TM. A clinicopathologic and molecular analysis of 34 mediastinal germ cell tumors suggesting different modes of teratoma development. Am J Surg Pathol.. 2018; 42:1662-73. DOI | PubMed
47. Lee T, Seo Y, Han J, Kwon GY. Analysis of chromosome 12p over-representation and clinicopathological features in mediastinal teratomas. Pathology.. 2019; 51:62-6. DOI
48. Schneider DT, Schuster AE, Fritsch MK. Genetic analysis of mediastinal nonseminomatous germ cell tumors in children and adolescents. Genes Chromosomes Cancer.. 2002; 34:115-25. DOI
49. Weissferdt A, Rodriguez-Canales J, Liu H, Fujimoto J, Wistuba II, Moran CA. Primary mediastinal seminomas: a comprehensive immunohistochemical study with a focus on novel markers. Hum Pathol.. 2015; 46:376-83. DOI | PubMed
50. Sung MT, Maclennan GT, Lopez-Beltran A, Zhang S, Montironi R, Cheng L. Primary mediastinal seminoma: a comprehensive assessment integrated with histology, immunohistochemistry, and fluorescence in situ hybridization for chromosome 12p abnormalities in 23 cases. Am J Surg Pathol.. 2008; 32:146-55. DOI | PubMed
51. Bagrodia A, Lee BH, Lee W. Genetic determinants of cisplatin resistance in patients with advanced germ cell tumors. J Clin Oncol.. 2016; 34:4000-7. DOI | PubMed |
52. Przygodzki RM, Moran CA, Suster S. Primary mediastinal and testicular seminomas: a comparison of K-ras-2 gene sequence and p53 immunoperoxidase analysis of 26 cases. Hum Pathol.. 1996; 27:975-9. DOI
53. Przygodzki RM, Hubbs AE, Zhao FQ, O'Leary TJ. Primary mediastinal seminomas: evidence of single and multiple KIT mutations. Lab Invest.. 2002; 82:1369-75. DOI | PubMed
54. Weissferdt A, Kalhor N, Rodriguez Canales J, Fujimoto J, Wistuba II, Moran CA. Primary mediastinal yolk sac tumors: an immunohistochemical analysis of 14 cases. Appl Immunohistochem Mol Morphol.. 2019; 27:125-33. DOI | PubMed
55. Moran CA, Suster S, Koss MN. Primary germ cell tumors of the mediastinum: III. Yolk sac tumor, embryonal carcinoma, choriocarcinoma, and combined nonteratomatous germ cell tumors of the mediastinum--a clinicopathologic and immunohistochemical study of 64 cases. Cancer.. 1997; 80:699-707. DOI | PubMed
56. Moran CA, Suster S. Primary mediastinal choriocarcinomas: a clinicopathologic and immunohistochemical study of eight cases. Am J Surg Pathol.. 1997; 21:1007-12. DOI | PubMed
57. Urbini M, Schepisi G, Bleve S. Primary mediastinal and testicular germ cell tumors in adolescents and adults: a comparison of genomic alterations and clinical implications. Cancers (Basel).. 2021; 13:5223. DOI | PubMed |
58. Necchi A, Bratslavsky G, Chung J. Genomic features for therapeutic insights of chemotherapy-resistant, primary mediastinal nonseminomatous germ cell tumors and comparison with gonadal counterpart. Oncologist.. 2019; 24:e142-5. DOI | PubMed |
59. McIntyre A, Summersgill B, Spendlove HE, Huddart R, Houlston R, Shipley J. Activating mutations and/or expression levels of tyrosine kinase receptors GRB7, RAS, and BRAF in testicular germ cell tumors. Neoplasia.. 2005; 7:1047-52. DOI | PubMed |
60. Ozgun G, Nappi L. Primary mediastinal germ cell tumors: a thorough literature review. Biomedicines.. 2023; 11:487. DOI | PubMed |
61. Wyvekens N, Sholl LM, Yang Y. Molecular correlates of male germ cell tumors with overgrowth of components resembling somatic malignancies. Mod Pathol.. 2022; 35:1966-73. DOI
62. Kernek KM, Brunelli M, Ulbright TM. Fluorescence in situ hybridization analysis of chromosome 12p in paraffin-embedded tissue is useful for establishing germ cell origin of metastatic tumors. Mod Pathol.. 2004; 17:1309-13. DOI
63. Warmke LM, Cheng L, Sperling RM, Sen JD, Ulbright TM. Atypical cartilage in type II germ cell tumors of the mediastinum show significantly different patterns of IDH1/2 mutations from conventional chondrosarcoma. Mod Pathol.. 2022; 35:1636-43. DOI | PubMed
64. Fichtner A, Richter A, Filmar S. The detection of isochromosome i(12p) in malignant germ cell tumours and tumours with somatic malignant transformation by the use of quantitative real-time polymerase chain reaction. Histopathology.. 2021; 78:593-606. DOI | PubMed
65. Levy DR, Agaram NP, Kao CS. Vasculogenic mesenchymal tumor: a clinicopathologic and molecular study of 55 cases of a distinctive neoplasm originating from mediastinal yolk sac tumor and an occasional precursor to angiosarcoma. Am J Surg Pathol.. 2021; 45:463-76. DOI
66. el-Khatib M, Chew FS. Embryonal carcinoma of the anterior mediastinum. AJR Am J Roentgenol.. 1998; 170:722. DOI | PubMed
67. Taylor J, Donoghue MT, Ho C. Germ cell tumors and associated hematologic malignancies evolve from a common shared precursor. J Clin Invest.. 2020; 130:6668-76. DOI
68. Fichtner A, Richter A, Filmar S. Primary mediastinal germ cell tumours: an immunohistochemical and molecular diagnostic approach. Histopathology.. 2022; 80:381-96. DOI
69. Bing Z, Pasha TL, Lal P, Tomaszewski JE. Expression of glial cell line-derived neurotropic factor receptor alpha-1 in immature teratomas. Am J Clin Pathol.. 2008; 130:892-6. DOI | PubMed
70. Weissferdt A, Moran CA. Mediastinal seminoma with florid follicular lymphoid hyperplasia: a clinicopathological and immunohistochemical study of six cases. Virchows Arch.. 2015; 466:209-15. DOI | PubMed
71. Cao D, Liu A, Wang F. RNA-binding protein LIN28 is a marker for primary extragonadal germ cell tumors: an immunohistochemical study of 131 cases. Mod Pathol.. 2011; 24:288-96. DOI
72. Rougemont AL, Tille JC. Role of HNF1β in the differential diagnosis of yolk sac tumor from other germ cell tumors. Hum Pathol.. 2018; 81:26-36. DOI | PubMed
73. Xiao GQ, Li F, Unger PD. ZBTB16: a novel sensitive and specific biomarker for yolk sac tumor. Mod Pathol.. 2016; 29:591-8. DOI
74. Schneider DT, Schuster AE, Fritsch MK. Genetic analysis of childhood germ cell tumors with comparative genomic hybridization. Klin Padiatr.. 2001; 213:204-11. DOI
75. Bussey KJ, Lawce HJ, Olson SB. Chromosome abnormalities of eighty-one pediatric germ cell tumors: sex-, age-, site-, and histopathology-related differences--a Children's Cancer Group study. Genes Chromosomes Cancer.. 1999; 25:134-46. PubMed
76. Houldsworth J, Korkola JE, Bosl GJ, Chaganti RS. Biology and genetics of adult male germ cell tumors. J Clin Oncol.. 2006; 24:5512-8. DOI | PubMed
77. Gurda GT, VandenBussche CJ, Yonescu R. Sacrococcygeal teratomas: clinico-pathological characteristics and isochromosome 12p status. Mod Pathol.. 2014; 27:562-8. DOI
78. Sheikine Y, Genega E, Melamed J, Lee P, Reuter VE, Ye H. Molecular genetics of testicular germ cell tumors. Am J Cancer Res.. 2012; 2:153-67. PubMed |
79. Bosl GJ, Ilson DH, Rodriguez E, Motzer RJ, Reuter VE, Chaganti RS. Clinical relevance of the i(12p) marker chromosome in germ cell tumors. J Natl Cancer Inst.. 1994; 86:349-55. DOI | PubMed
80. Kesler KA. Technique of mediastinal germ cell tumor resection. Oper. Tech. Thorac. Cardiovasc. Surg.. 2009; 14:55-65. DOI
81. André F, Fizazi K, Culine S. The growing teratoma syndrome: results of therapy and long-term follow-up of 33 patients. Eur J Cancer.. 2000; 36:1389-94. DOI
82. Bosl GJ, Gluckman R, Geller NL. VAB-6: an effective chemotherapy regimen for patients with germ-cell tumors. J Clin Oncol.. 1986; 4:1493-9. DOI
83. Kersh CR, Constable WC, Hahn SS. Primary malignant extragonadal germ cell tumors. An analysis of the effect of the effect of radiotherapy. Cancer.. 1990; 65:2681-5. DOI | PubMed
84. Biswas B, Dabkara D, Sengupta M. Multimodality treatment outcome in patients with primary malignant mediastinal germ cell tumor in adults. Cancer Rep (Hoboken).. 2021; 4:e1306. DOI | PubMed |
85. Dechaphunkul A, Sakdejayont S, Sathitruangsak C, Sunpaweravong P. Clinical Characteristics and Treatment Outcomes of Patients with Primary Mediastinal Germ Cell Tumors: 10-Years' Experience at a Single Institution with a Bleomycin-Containing Regimen. Oncol Res Treat.. 2016; 39:688-94. DOI
86. Liu TZ, Zhang DS, Liang Y. Treatment strategies and prognostic factors of patients with primary germ cell tumors in the mediastinum. J Cancer Res Clin Oncol.. 2011; 137:1607-12. DOI | PubMed |
87. Rodney AJ, Tannir NM, Siefker-Radtke AO. Survival outcomes for men with mediastinal germ-cell tumors: the University of Texas M. D. Anderson Cancer Center experience. Urol Oncol.. 2012; 30:879-85. DOI | PubMed |
88. Sakurai H, Asamura H, Suzuki K, Watanabe S, Tsuchiya R. Management of primary malignant germ cell tumor of the mediastinum. Jpn J Clin Oncol.. 2004; 34:386-92. DOI | PubMed
89. Gangadhar B, Nagpal C, Sharma A. Primary mediastinal germ cell tumors: a real-world analysis of clinical characteristics, treatment, and survival outcomes from two tertiary cancer centers in India. JCO Glob Oncol.. 2025; 11:e2500099. DOI
90. De Latour B, Fadel E, Mercier O. Surgical outcomes in patients with primary mediastinal non-seminomatous germ cell tumours and elevated post-chemotherapy serum tumour markers. Eur J Cardiothorac Surg.. 2012; 42DOI
91. Vuky J, Bains M, Bacik J. Role of postchemotherapy adjunctive surgery in the management of patients with nonseminoma arising from the mediastinum. J Clin Oncol.. 2001; 19:682-8. DOI
92. Hidalgo M, Paz-Ares L, Rivera F. Mediastinal non-seminomatous germ cell tumours (MNSGCT) treated with cisplatin-based combination chemotherapy. Ann Oncol.. 1997; 8:555-9. DOI
93. Necchi A, Giannatempo P, Lo Vullo S. A prognostic model including pre- and postsurgical variables to enhance risk stratification of primary mediastinal nonseminomatous germ cell tumors: the 27-year experience of a referral center. Clin Genitourin Cancer.. 2015; 13:87-93.e1. DOI
94. Rivera C, Arame A, Jougon J. Prognostic factors in patients with primary mediastinal germ cell tumors, a surgical multicenter retrospective study. Interact Cardiovasc Thorac Surg.. 2010; 11:585-9. DOI
95. Winter C, Zengerling F, Busch J. How to classify, diagnose, treat and follow-up extragonadal germ cell tumors? A systematic review of available evidence. World J Urol.. 2022; 40:2863-78. DOI | PubMed |
96. Hinton S, Catalano PJ, Einhorn LH. Cisplatin, etoposide and either bleomycin or ifosfamide in the treatment of disseminated germ cell tumors: final analysis of an intergroup trial. Cancer.. 2003; 97:1869-75. DOI | PubMed
97. Ranganath P, Kesler KA, Einhorn LH. Perioperative morbidity and mortality associated with bleomycin in primary mediastinal nonseminomatous germ cell tumor. J Clin Oncol.. 2016; 34:4445-6. DOI | PubMed
98. O'Sullivan JM, Huddart RA, Norman AR, Nicholls J, Dearnaley DP, Horwich A. Predicting the risk of bleomycin lung toxicity in patients with germ-cell tumours. Ann Oncol.. 2003; 14:91-6. DOI | PubMed
99. Andrade RS, Kesler KA, Wilson JL. Short- and long-term outcomes after large pulmonary resection for germ cell tumors after bleomycin-combination chemotherapy. Ann Thorac Surg.. 2004; 78DOI
100. Stram AR, Kesler KA. Mediastinal germ cell tumors: updates in diagnosis and management. Surg Oncol Clin N Am.. 2020; 29:571-9. DOI | PubMed
101. Kesler KA, Rieger KM, Hammoud ZT. A 25-year single institution experience with surgery for primary mediastinal nonseminomatous germ cell tumors. Ann Thorac Surg.. 2008; 85:371-8. DOI
102. Feldman DR, Voss MH, Jacobsen EP. Clinical features, presentation, and tolerance of platinum-based chemotherapy in germ cell tumor patients 50 years of age and older. Cancer.. 2013; 119:2574-81. DOI
103. Secondino S, Badoglio M, Rosti G. ; EBMT Cellular THERAPY &amp; Immunobiology WP. High-dose chemotherapy with autologous stem cell transplants in adult primary non-seminoma mediastinal germ-cell tumors. A report from the Cellular Therapy and Immunobiology working party of the EBMT. ESMO Open.. 2024; 9:103692. DOI | PubMed |
104. Richardson NH, Taza F, Abonour R. High-dose chemotherapy and peripheral blood stem cell transplantation as salvage therapy in primary mediastinal nonseminomatous germ cell tumors: The Indiana University experience. Cancer.. 2024; 130:3115-22. DOI
105. Daugaard G, Skoneczna I, Aass N. A randomized phase III study comparing standard dose BEP with sequential high-dose cisplatin, etoposide, and ifosfamide (VIP) plus stem-cell support in males with poor-prognosis germ-cell cancer. An intergroup study of EORTC, GTCSG, and Grupo Germinal (EORTC 30974). Ann Oncol.. 2011; 22:1054-61. DOI | PubMed |
106. Wang J, Bi N, Wang X. Role of radiotherapy in treating patients with primary malignant mediastinal non-seminomatous germ cell tumor: a 21-year experience at a single institution. Thorac Cancer.. 2015; 6:399-406. DOI | PubMed |
107. Gutekunst M, Oren M, Weilbacher A. p53 hypersensitivity is the predominant mechanism of the unique responsiveness of testicular germ cell tumor (TGCT) cells to cisplatin. PLoS ONE.. 2011; 6:e19198. DOI | PubMed |
108. Houldsworth J, Xiao H, Murty VV. Human male germ cell tumor resistance to cisplatin is linked to TP53 gene mutation. Oncogene.. 1998; 16:2345-9. DOI
109. Timmerman DM, Eleveld TF, Gillis AJM. The role of TP53 in cisplatin resistance in mediastinal and testicular germ cell tumors. Int J Mol Sci.. 2021; 22DOI | PubMed |
110. Bacon JVW, Giannatempo P, Cataldo G. TP53 alterations are associated with poor survival in patients with primary mediastinal nonseminoma germ cell tumors. Oncologist.. 2022; 27:e912-5. DOI | PubMed |
111. Port M, Glaesener S, Ruf C. Micro-RNA expression in cisplatin resistant germ cell tumor cell lines. Mol Cancer.. 2011; 10:52. DOI | PubMed |
112. Selle F, Wittnebel S, Biron P. A phase II trial of high-dose chemotherapy (HDCT) supported by hematopoietic stem-cell transplantation (HSCT) in germ-cell tumors (GCTs) patients failing cisplatin-based chemotherapy: the Multicentric TAXIF II study. Ann Oncol.. 2014; 25:1775-82. DOI
113. De Giorgi U, Demirer T, Wandt H. ; Solid Tumor Working Party of the European Group for Blood and Marrow Transplantation. Second-line high-dose chemotherapy in patients with mediastinal and retroperitoneal primary non-seminomatous germ cell tumors: the EBMT experience. Ann Oncol.. 2005; 16:146-51. DOI
114. Adra N, Abonour R, Althouse SK, Albany C, Hanna NH, Einhorn LH. High-dose chemotherapy and autologous peripheral-blood stem-cell transplantation for relapsed metastatic germ cell tumors: The Indiana University Experience. J Clin Oncol.. 2017; 35:1096-102. DOI
115. Banna GL, De Giorgi U, Ferrari B. Is high-dose chemotherapy after primary chemotherapy a therapeutic option for patients with primary mediastinal nonseminomatous germ cell tumor? Biol Blood Marrow Transplant. 2006;12:1085-91.DOI
116. Feldman DR, Patil S, Trinos MJ. Progression-free and overall survival in patients with relapsed/refractory germ cell tumors treated with single-agent chemotherapy: endpoints for clinical trial design. Cancer.. 2012; 118:981-6. DOI
117. Albany C, Fazal Z, Singh R. A phase 1 study of combined guadecitabine and cisplatin in platinum refractory germ cell cancer. Cancer Med.. 2021; 10:156-63. DOI | PubMed |
118. Oing C, Verem I, Mansour WY, Bokemeyer C, Dyshlovoy S, Honecker F. 5-azacitidine exerts prolonged pro-apoptotic effects and overcomes cisplatin-resistance in non-seminomatous germ cell tumor cells. Int J Mol Sci.. 2018; 20DOI | PubMed |
119. Adra N, Einhorn LH, Althouse SK. Phase II trial of pembrolizumab in patients with platinum refractory germ-cell tumors: a Hoosier Cancer Research Network Study GU14-206. Ann Oncol.. 2018; 29:209-14. DOI
120. Feldman DR, Einhorn LH, Quinn DI. A phase 2 multicenter study of tivantinib (ARQ 197) monotherapy in patients with relapsed or refractory germ cell tumors. Investig New Drugs.. 2013; 31:1016-22. DOI
121. Jain A, Brames MJ, Vaughn DJ, Einhorn LH. Phase II clinical trial of oxaliplatin and bevacizumab in refractory germ cell tumors. Am J Clin Oncol.. 2014; 37:450-3. DOI | PubMed
122. Maroto P, Huddart R, Garcia del Muro X. Brief report: phase II multicenter study of temozolomide in patients with cisplatin-resistant germ cell tumors. Oncology.. 2011; 80:219-22. DOI
123. Feldman DR, Sheinfeld J, Bajorin DF. TI-CE high-dose chemotherapy for patients with previously treated germ cell tumors: results and prognostic factor analysis. J Clin Oncol.. 2010; 28:1706-13. DOI
124. Shamash J, Powles T, Mutsvangwa K. A phase II study using a topoisomerase I-based approach in patients with multiply relapsed germ-cell tumours. Ann Oncol.. 2007; 18:925-30. DOI
125. Kollmannsberger C, Beyer J, Liersch R. Combination chemotherapy with gemcitabine plus oxaliplatin in patients with intensively pretreated or refractory germ cell cancer: a study of the German Testicular Cancer Study Group. J Clin Oncol.. 2004; 22:108-14. DOI
126. Kollmannsberger C, Rick O, Klaproth H. Irinotecan in patients with relapsed or cisplatin-refractory germ cell cancer: a phase II study of the German Testicular Cancer Study Group. Br J Cancer.. 2002; 87:729-32. DOI | PubMed |
127. Koul S, McKiernan JM, Narayan G. Role of promoter hypermethylation in cisplatin treatment response of male germ cell tumors. Mol Cancer.. 2004; 3:16. DOI | PubMed |
128. Wermann H, Stoop H, Gillis AJ. Global DNA methylation in fetal human germ cells and germ cell tumours: association with differentiation and cisplatin resistance. J Pathol.. 2010; 221:433-42. DOI
129. Beyrouthy MJ, Garner KM, Hever MP. High DNA methyltransferase 3B expression mediates 5-aza-deoxycytidine hypersensitivity in testicular germ cell tumors. Cancer Res.. 2009; 69:9360-6. DOI
130. Miranda-Gonçalves V, Lobo J, Guimarães-Teixeira C. The component of the m6A writer complex VIRMA is implicated in aggressive tumor phenotype, DNA damage response and cisplatin resistance in germ cell tumors. J Exp Clin Cancer Res.. 2021; 40:268. DOI | PubMed |
131. Fizazi K, Pagliaro L, Laplanche A. Personalised chemotherapy based on tumour marker decline in poor prognosis germ-cell tumours (GETUG 13): a phase 3, multicentre, randomised trial. Lancet Oncol.. 2014; 15:1442-50. DOI
132. Ligia Cebotaru C, Zenovia Antone N, Diana Olteanu E. A phase II single institution single arm prospective study with paclitaxel, ifosfamide and cisplatin (TIP) as first-line chemotherapy in high-risk germ cell tumor patients with more than ten years follow-up and retrospective correlation with ERCC1, Topoisomerase 1, 2A, p53 and HER-2 expression. J BUON.. 2016; 21:698-708. PubMed
133. Lafin JT, Bagrodia A, Woldu S, Amatruda JF. New insights into germ cell tumor genomics. Andrology.. 2019; 7:507-15. DOI | PubMed
134. Einhorn LH, Brames MJ, Heinrich MC, Corless CL, Madani A. Phase II study of imatinib mesylate in chemotherapy refractory germ cell tumors expressing KIT. Am J Clin Oncol.. 2006; 29:12-3. DOI
135. Subbiah V, Meric-Bernstam F, Mills GB. Next generation sequencing analysis of platinum refractory advanced germ cell tumor sensitive to Sunitinib (Sutent®) a VEGFR2/PDGFRβ/c-kit/ FLT3/RET/CSF1R inhibitor in a phase II trial. J Hematol Oncol.. 2014; 7:52. DOI | PubMed |
136. Cheng X, Yu H, Li J. Dramatic response to local radiotherapy in a refractory metastatic mediastinal yolk sac tumor patient harboring a germline BRCA2 frameshift mutation: a case report. Cancer Biol Ther.. 2022; 23:393-400. DOI | PubMed |
137. Leonard JT, Raess PW, Dunlap J, Hayes-Lattin B, Tyner JW, Traer E. Functional and genetic screening of acute myeloid leukemia associated with mediastinal germ cell tumor identifies MEK inhibitor as an active clinical agent. J Hematol Oncol.. 2016; 9:31. DOI | PubMed |
138. Pan J, Yin W, Chen Y. Sustained response to anti-PD-1 therapy in combination with nab-paclitaxel in metastatic testicular germ cell tumor harboring the KRAS-G12V mutation: a case report. Urol Int.. 2025; 109:197-205. DOI
139. Meng J, Gao J, Li X. TIMEAS, a promising method for the stratification of testicular germ cell tumor patients with distinct immune microenvironment, clinical outcome and sensitivity to frontline therapies. Cell Oncol (Dordr).. 2023; 46:745-59. DOI
140. Devouassoux-Shisheboran M, Mauduit C, Bouvier R. Expression of hMLH1 and hMSH2 and assessment of microsatellite instability in testicular and mediastinal germ cell tumours. Mol Hum Reprod.. 2001; 7:1099-105. DOI
141. Aguiar Bujanda D, Pérez Cabrera D, Croissier Sánchez L. Extragonadal germ cell tumors of the mediastinum and retroperitoneum: a surveillance, epidemiology, and end results-based study. Am J Clin Oncol.. 2022; 45:493-500. DOI | PubMed
142. Wu P, Yang Y, Yu Z, Zhao L, Feng S. Clinical features and survival outcomes in children and adolescents with malignant mediastinal germ cell tumors based on surveillance, epidemiology, and end results database analysis. J Surg Res.. 2023; 288:362-71. DOI
143. International Germ Cell Consensus Classification: a prognostic factor-based staging system for metastatic germ cell cancers. International Germ Cell Cancer Collaborative Group. J Clin Oncol.. 1997; 15:594-603. DOI
144. Kollmannsberger C, Nichols C, Meisner C, Mayer F, Kanz L, Bokemeyer C. Identification of prognostic subgroups among patients with metastatic ‘IGCCCG poor-prognosis’ germ-cell cancer: an explorative analysis using cart modeling. Ann Oncol.. 2000; 11:1115-20. DOI | PubMed
145. Mazumdar M, Bacik J, Tickoo SK. Cluster analysis of p53 and Ki67 expression, apoptosis, alpha-fetoprotein, and human chorionic gonadotrophin indicates a favorable prognostic subgroup within the embryonal carcinoma germ cell tumor. J Clin Oncol.. 2003; 21:2679-88. DOI
146. Moran CA, Suster S. Primary germ cell tumors of the mediastinum: I. Analysis of 322 cases with special emphasis on teratomatous lesions and a proposal for histopathologic classification and clinical staging. Cancer.. 1997; 80:681-90. DOI
147. Hartmann JT, Nichols CR, Droz JP. Prognostic variables for response and outcome in patients with extragonadal germ-cell tumors. Ann Oncol.. 2002; 13:1017-28. DOI
148. Fedyanin M, Tryakin A, Mosyakova Y. Prognostic factors and efficacy of different chemotherapeutic regimens in patients with mediastinal nonseminomatous germ cell tumors. J Cancer Res Clin Oncol.. 2014; 140:311-8. DOI | PubMed |
149. Schneider DT, Calaminus G, Reinhard H. Primary mediastinal germ cell tumors in children and adolescents: results of the German cooperative protocols MAKEI 83/86, 89, and 96. J Clin Oncol.. 2000; 18:832-9. DOI
150. Géczi L, Budai B, Polk N, Fazekas F, Bodrogi I, Biró K. Neutrophil-to-lymphocyte ratio in primary mediastinal germ cell tumors: a retrospective analysis of &gt; 20 years single institution experience. Curr Probl Cancer.. 2020; 44:100537. DOI | PubMed
151. Zheng Z, Wu Z, Hu Y, Zhang Y, Ding C, Zou X. Development of A nomogram for predicting survival of patients with primary mediastinal germ cell tumor based on SEER Database. Zhongguo Fei Ai Za Zhi.. 2023; 26:193-203. DOI | PubMed |
152. Guibert N, Attias D, Pontier S, Berjaud J, Lavialle-Guillautreau V, Didier A. Mediastinal teratoma and trichoptysis. Ann Thorac Surg.. 2011; 92:351-3. DOI | PubMed
153. McLeod NP, Vallely MP, Mathur MN. Massive immature mediastinal teratoma extending into the left pleural cavity. Heart Lung Circ.. 2005; 14:45-7. DOI | PubMed
154. Norris HJ, Zirkin HJ, Benson WL. Immature (malignant) teratoma of the ovary: a clinical and pathologic study of 58 cases. Cancer.. 1976; 37:2359-72. DOI | PubMed
155. Hartmann JT, Fossa SD, Nichols CR. Incidence of metachronous testicular cancer in patients with extragonadal germ cell tumors. J Natl Cancer Inst.. 2001; 93:1733-8. DOI
156. Sarkaria IS, Bains MS, Sood S. Resection of primary mediastinal non-seminomatous germ cell tumors: a 28-year experience at memorial sloan-kettering cancer center. J Thorac Oncol.. 2011; 6:1236-41. DOI
157. Schneider BP, Kesler KA, Brooks JA, Yiannoutsos C, Einhorn LH. Outcome of patients with residual germ cell or non-germ cell malignancy after resection of primary mediastinal nonseminomatous germ cell cancer. J Clin Oncol.. 2004; 22:1195-200. DOI | PubMed
158. Palmer RD, Murray MJ, Saini HK. ; Children’s Cancer and Leukaemia Group. Malignant germ cell tumors display common microRNA profiles resulting in global changes in expression of messenger RNA targets. Cancer Res.. 2010; 70:2911-23. DOI
159. Kan SY, Scarpini CG, Ward D. Mediastinal NUT Carcinoma With Raised Serum Alpha-Fetoprotein Mimicking a Malignant Germ Cell Tumor: Suspicion Raised Due to Negative Serum miR-371a-3p Levels. Pediatr Dev Pathol.. 2025; 28:338-45. DOI | PubMed |