Adult Testicular Germ Cell Tumors Research Articles

Genomic landscape of adult testicular germ cell tumours in the 100,000 Genomes Project

Testicular germ cell tumours (TGCT), which comprise seminoma and non-seminoma subtypes, are the most common cancers in young men. In this study, we present a comprehensive whole genome sequencing analysis of adult TGCTs. Leveraging samples from participants recruited via the UK National Health Service and data from the Genomics England 100,000 Genomes Project, our results provide an extended description of genomic elements underlying TGCT pathogenesis. This catalogue offers a comprehensive, high-resolution map of copy number alterations, structural variation, and key global genome features, including mutational signatures and analysis of extrachromosomal DNA amplification. This study establishes correlations between genomic alterations and histological diversification, revealing divergent evolutionary trajectories among TGCT subtypes. By reconstructing the chronological order of driver events, we identify a subgroup of adult TGCTs undergoing relatively late whole genome duplication. Additionally, we present evidence that human leukocyte antigen loss is a more prevalent mechanism of immune disruption in seminomas. Collectively, our findings provide valuable insights into the developmental and immune modulatory processes implicated in TGCT pathogenesis and progression.

Parental occupations at birth and risk of adult testicular germ cell tumors in offspring: a French nationwide case-control study.

Testicular germ cell tumors (TGCT) are the most frequent cancer in young men in developed countries. Parental occupational exposures during early-life periods are suspected to increase TGCT risk. The objective was to estimate the association between parental occupations at birth and adult TGCT. A case-control study was conducted, including 454 TGCT cases aged 18-45 from 20 French university hospitals, matched to 670 controls based on region and year of birth. Data collected from participants included parental jobs at birth coded according to the International Standard Classification of Occupation-1968 and the French nomenclature of activities-1999. Odds ratios (OR) for TGCT and 95% confidence intervals (CI) were estimated using conditional logistic regression, adjusting for TGCT risk factors. Paternal jobs at birth as service workers (OR = 1.98, CI 1.18-3.30), protective service workers (OR = 2.40, CI 1.20-4.81), transport equipment operators (OR = 1.96, CI 1.14-3.37), specialized farmers (OR = 2.66, CI 1.03-6.90), and maternal jobs as secondary education teachers (OR = 2.27, CI 1.09-4.76) or in secondary education (OR = 2.35, CI 1.13-4.88) were significantly associated with adult TGCT. The risk of seminoma was increased for the above-mentioned paternal jobs and that of non-seminomas for public administration and defence; compulsory social security (OR = 1.99, CI 1.09-3.65); general, economic, and social administration (OR = 3.21, CI 1.23-8.39) for fathers; and secondary education teacher (OR = 4.67, CI 1.87-11.67) and secondary education (OR = 3.50, CI 1.36-9.01) for mothers. Some paternal jobs, such as service workers, transport equipment operators, or specialized farmers, and maternal jobs in secondary education seem to be associated with an increased risk of TGCT with specific features depending on the histological type. These data allow hypotheses to be put forward for further studies as to the involvement of occupational exposures in the risk of developing TGCT, such as exposure to pesticides, solvents, or heavy metals.

Abstract 2497: Inherited copy number variants that increase risk of developing pediatric germ cell tumors with a particular focus on the X chromosome

Abstract Pediatric malignant germ cell tumors (GCTs) are heterogeneous but are grouped together due to the presumed common cell of origin, the primordial germ cell (PGC). Little is known about etiology; however, evidence supporting in utero origins of pediatric and adult GCT suggests that disruptions in normal germ cell development are likely to be highly relevant. Germline copy number variants (CNVs) are a plausible source of inherited genetic variation and have not been thoroughly evaluated to date. CNVs on the X chromosome are of particular interest because individuals with both Klinefelter syndrome (47, XXY) and Turner syndrome (45, X) are at increased risk of pediatric GCT, suggesting that alterations in X chromosome dosage contribute to etiology. A family study of adult testicular cancer where at least one member had bilateral cancer identified a significant linkage peak at Xq27 (hLOD=4.7). In addition, somatic copy number gains of chromosome X are frequently seen in adult testicular germ cell tumors. Given these findings in adult GCT, similar aberrations may also be relevant risk factors for the pediatric group. Pediatric GCT samples were obtained from a Children’s Oncology Group study and state biobank programs in Michigan and California. Genotyping array data were generated using the Illumina HumanCoreExome Beadchip (Illumina, San Diego). CNV calls were made for 2,002 GCT cases and 1,402 controls with high quality intensity data using Genvisis, which has specialized algorithms to make CNV calls on the X chromosome. Klinefelter syndrome cases (n=27) were excluded from the analyses. No study sample had classic Turner syndrome; however, one female case had a giant 51Mb deletion of Xq. Analyses were performed for females-only, males-only, and everyone together. We identified two regions that are study-wide significant on chromosome X at Xq27.1 and Xp11.2 and one nominally significant near Xq28. The most significant finding was identified in females-only and is located within a region that encodes genes within the SPANX family. Evidence suggests these genes affect germ cells; however, supporting data is reported in spermatozoa rather than oocytes. The events in our study were large (240kb), had similar breakpoints, and appear to be flanked by repetitive DNA that might lead to recurrent events at the same region. The variant was present in the control samples within gnomAD at a low allele frequency (0.18%). In our study, both deletions and duplications were noted: 11 female cases (1 or 2 expected based on gnomAD allele frequencies) and 0 female controls (0-1 expected). The finding was not replicated in males (6 male cases and 5 male controls harbored similar CNVs). We are in the process of validating these in silico and potentially via quantitative PCR. Findings may shed light on disruptions in normal development that may increase risk of GCT. Citation Format: Shannon S. Cigan, John J. Meredith, John Zaharick, Erica Langer, Anthony J. Hooten, John A. Lane, Nathan Pankratz, Jenny N. Poynter. Inherited copy number variants that increase risk of developing pediatric germ cell tumors with a particular focus on the X chromosome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2497.

Abstract 874: Predicted leukocyte telomere length and risk of germ cell tumors

Abstract Genetically predicted leukocyte telomere length (LTL) has been evaluated in a number of studies of childhood and adult cancer, with evidence that longer predicted LTL is associated with increased cancer risk. We use Mendelian Randomization (MR) to test whether genetically predicted LTL is associated with germ cell tumors (GCT) in pediatric, adolescent, and adult cases using six SNPs that are validated predictors of LTL. A seventh SNP in the validated genetic predictor of LTL, rs2736100, a variant on TERT, is associated with adult testicular GCT (TGCT); therefore, in our overall analysis, we removed this SNP to avoid violating MR assumptions. Pediatric GCT samples were obtained from a Children's Oncology Group study and state biobank programs in Michigan and California. Genotyping array data were generated using the Illumina HumanCoreExome Beadchip. For each SNP, we estimated main effects for pediatric GCT within 610 complete case-parent trios using the transmission disequilibrium test. We did the same in an independent case-control dataset of 803 pediatric cases and 1,022 controls stratified by ancestry using multivariable logistic regression adjusted for sex, ancestry-specific principal components (PCs), and study site. Effect estimates were meta-analyzed and used to perform the MR analyses. In a separate sample of 396 cases and 1,589 matched controls from the UK Biobank, genotyping array data was used to evaluate the association between a polygenic risk score capturing genetically predicted LTL and TGCT in men <50 years old using multivariable logistic regression adjusted for global ancestry PCs (PC1-10). We observed a positive association between LTL and overall risk of GCT in both the pediatric cases (OR [95% CI] = 2.52 [1.19, 5.34] per kb of LTL; p=0.016) and the adult TGCT cases (OR [95% CI] = 1.94 [0.60, 6.28] per kb of LTL; p=0.266). Subgroup analyses in our pediatric GCT cases show consistent findings of longer LTL and risk across subgroups, with the exception of teratomas. Additionally, we evaluated the individual SNP effect of TERT/rs2736100-A and observed a significant association in pediatric GCT (OR [95% CI] = 1.21 [1.09, 1.35]; p =0.0003) which is driven by male cases diagnosed in adolescence (age at dx 11-19 years). A significant association was also observed between TERT/rs2736100-A and adult TGCT (OR [95% CI] = 1.25 [1.07, 1.46]; p=0.005). Similar to analyses of other childhood and adult cancers, our results indicate that longer telomere length is associated with an increased risk of GCT in pediatric, adolescent, and adult GCT. We also observed a strong association between pediatric GCT and TERT and confirmed previous findings with adult TGCT. These results indicate further analyses of variants in genes relevant for telomere function and maintenance are warranted. Citation Format: Shannon S. Cigan, Ava C. Kelley, John J. Meredith, Erica K. Langer, Anthony J. Hooten, John A. Lane, Benjamin R. Cole, Nathan Pankratz, Jenny Poynter. Predicted leukocyte telomere length and risk of germ cell tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 874.

Molecular Biology of Pediatric and Adult Male Germ Cell Tumors.

Simple SummaryAlthough testicular germ cell tumors (TGCTs) are rare pediatric malignancies, they are the most common malignancies in young adult men. The similarities and differences between TGCTs in adults and children, taking into account the clinic presentation, biology, and molecular changes, are underexplored. In this paper, we aim to provide an overview of the molecular aspects of TGCTs, drawing a parallel between the findings in adult and pediatric groups.Cancer is a leading cause of death by disease in children and the second most prevalent of all causes in adults. Testicular germ cell tumors (TGCTs) make up 0.5% of pediatric malignancies, 14% of adolescent malignancies, and are the most common of malignancies in young adult men. Although the biology and clinical presentation of adult TGCTs share a significant overlap with those of the pediatric group, molecular evidence suggests that TGCTs in young children likely represent a distinct group compared to older adolescents and adults. The rarity of this cancer among pediatric ages is consistent with our current understanding, and few studies have analyzed and compared the molecular basis in childhood and adult cancers. Here, we review the major similarities and differences in cancer genetics, cytogenetics, epigenetics, and chemotherapy resistance between pediatric and adult TGCTs. Understanding the biological and molecular processes underlying TGCTs may help improve patient outcomes, and fuel further investigation and clinical research in childhood and adult TGCTs.

Adolescent and Young Adult Testicular Germ Cell Tumors: Special Considerations.

While testicular germ cell tumors (T-GCTs) make up only 0.5% of pediatric malignancies and less than 2% of adult malignancies, they comprise 14% of adolescent malignancies, making it the most common solid tumor in this age group. The transition in incidence at this age is also accompanied by a transition in tumor histology with adolescents having mostly pure embryonal carcinoma and mixed nonseminomatous germ cell tumors. Similar to T-GCTs of all ages, surgical excision with orchiectomy is the standard initial step in treatment. Chemotherapy, retroperitoneal lymph node dissection, and targeted treatment of distant metastases make even widely disseminated disease treatable and curable. For this reason, in many ways, the future focus has expanded beyond survival alone to emphasize quality of life issues such as fertility and hypogonadism. However, adolescents remain the age group least studied or understood as they fall in between the ages included in most study designs. Also, they require the most psychosocial support because of the challenges unique to the adolescent period. In this review, we aim to highlight the known outcome data for T-GCTs in this population and also to discuss the unique aspects of treatment and support for this age group.

Follicle-stimulating hormone receptor (FSHR) a promising novel target for cancer diagnosis in seminoma and embryonal carcinoma

Adult testicular germ cell tumors (TGCTs) are the most frequent malignant tumors in male patients aged 15–45 years, their incidence is increasing in recent years. There are two main subclasses of TGCTs: seminomas (SE) and non-seminomatous germ cell tumors (NSGCTs). SE have histological features of primordial germ cells, whereas NSGCTs have varying degrees of differentiation (i.e. embryonal carcinoma, EC), they present distinctive clinical features and differ for therapy and prognosis. NSGCTs tend to be metastatic at presentation, and have a worse prognosis than seminomas at an equivalent stage of disease. Despite general advances in the management of TGCTs, the molecular bases underlying their progression remain almost unknown. The effects of the Follicle-stimulating hormone (FSH), central hormone in mammalian reproductive biology, are mediated by FSHR, which was believed to be expressed primarily in ovary and testis. Recently, FSHR expression has been shown in the blood vessels of different solid tumors, including prostate, urothelial and breast carcinomas, suggesting a role in neoangiogenesis. The expression of FSHR at the periphery of tumors, also suggests that FSHR may be of relevance to the metastatic process. In normal human testis, estrogen physiological actions are mediated by estrogen receptor (ER) β and highly variable ERβ expression has been reported in the different TGCTs. ERβ loss is associated with advanced tumor stage in several cancers and previously, we showed a higher expression of ERβ1 in SE with respect EC. In this study, we evaluated the expression of FSHR in normal and neoplastic human testis tissues. Further, we compared FSHR expression with that of ERβ1 in the same samples. In normal testes, immunohistochemical studies showed the presence of FSHR prevalently in somatic testicular cells, while ERβ1 is expressed both in somatic and germinal testicular cells. Intriguingly, we discovered that FSHR was strongly expressed in EC and absent in SE. Conversely, immunostaining for ERβ1 revealed higher intensity in SE as compared to EC. These data suggest distinct physiopathological roles for the two receptors in TGCTs progression, being ERβ1 protective and FSHR harmful. Our data report for the first time the expression of FSHR in TGCTs, suggesting its possible involvement in testicular carcinogenesis. FSHR may be considered an useful molecular marker to distinguish seminoma from embryonal carcinoma, the most common TGCTs subtypes, and this could be informative in clinical decision making and patient counseling.

Testicular germ cell tumor genomics.

Testicular germ cell tumors (TGCTs) are a model for curable cancer because of exquisite chemosensitivity and incorporation of multimodal therapy. Nevertheless, our ability to predict metastases in early-stage disease and responders to chemotherapy in advanced disease is limited. Treatment options for cisplatin-resistant disease are sparse. A further understanding of TGCT biology may allow for more precise patient counseling and identify novel therapies in patients with cisplatin-resistant disease. Adult TGCTs are characterized by frequent chromosomal anomalies and low rates of somatic mutations. Large-scale integrated molecular analysis of early-stage TGCT patients is actively underway. In addition to ubiquitous gain of isochromosome 12p, current molecular studies have confirmed mutations of previously described genes (i.e., KIT and KRAS) and described novel mutations. Analysis of cisplatin-resistant cases has identified high rates of alterations within the TP53-MDM2 axis and a high proportion of patients with potentially actionable targets, including TP53-MDM2, PI3 kinase, and MAPK signaling pathway alterations. The role of epigenetics in TGCT development and prognosis is also being further characterized. Further molecular characterization of TGCT may allow for avoidance of unnecessary treatment in patients with early-stage disease and also provide new treatment options in patients with cisplatin-resistant disease.

Abstract LB-374: Variants in BAK1 and SPRY4 are associated with pediatric germ cell tumors

Abstract Introduction. Pediatric germ cell tumors (GCT) are a rare form of childhood cancer that originate from the primordial germ cell. Little is known about etiology and few risk factors have been identified. Both pediatric GCT and adult testicular GCT (TGCT) appear to initiate in utero and thus may share etiologic factors. Several SNPs have been associated with adult TGCT in genome-wide association studies (GWAS). Here we test whether these SNPs are associated with pediatric GCT. Methods. This case-parent triad study includes cases diagnosed with GCT at age 0-19 years between July 1, 2008 and December 31, 2013 who were identified through the Children's Cancer Research Network (CCRN). Buccal cell DNA was collected from cases and their biological parents. We identified 21 SNPs at 15 independent loci from GWAS of adult TGCT and estimated main effects for pediatric GCT using the transmission disequilibrium test (TDT). We used Estimation of Maternal, Imprinting and interaction effects using Multinomial modelling (EMIM) to evaluate maternal effects in non-Hispanic white trios. A Bonferroni correction was used to account for multiple comparisons. Results. DNA was available for 364 complete trios. The SPRY4 SNP rs4624820 was significantly associated with reduced risk of GCT (OR [95% CI]: 0.69 [0.56, 0.85]; Table). BAK1 SNP rs210138 was associated with an increased risk estimate for GCT (OR [95% CI]: 1.70 [1.32, 2.18]), with a particularly strong estimated effect for testis tumors (OR [95% CI]: 3.31 [1.89, 5.79]). Nominal associations (p<0.05) were noted for 5 additional loci. Maternal effects were observed for KITLG SNP rs4474514 (OR [95% CI]: 1.87 [1.29, 2.71]) and rs7221274 (OR [95% CI]: 2.07 [1.43, 2.99]), near TEX14, RAD51C, and PPM1E. Conclusions. We observed significant associations between SNPs in SPRY4 and BAK1 and pediatric GCTs, with a particularly strong association between the SNP in BAK1 and testis tumors. These SNPs may impact risk of GCT through apoptosis pathways. The results of this analysis support that there are common genetic risk factors for pediatric and adult GCT. Associations between adult TGCT GWAS variants and risk of pediatric GCTMain effectsMaternal effectsMarker NameOriginal GWAS markerLocusGeneMAFRisk alleleOR (95% CI)p-valueOR (95% CI)p-valuers2072499rs20724991q22SLC0.3578C1.21 (0.96, 1.51)0.098990.84 (0.60, 1.18)0.31475rs3790672rs37906721q24.1UCK20.3104C1.01 (0.81, 1.26)0.911501.19 (0.70, 1.39)0.32380rs3773832rs105104523p24.3DAZL0.2953T0.92 (0.73, 1.14)0.431000.99 (0.70, 1.39)0.93238rs8336rs170214634q22.2HPGDS0.3977G0.93 (0.75, 1.15)0.478800.85 (0.59, 1.21)0.35992rs2720460rs27204604q24CENPE0.3606G1.09 (0.88, 1.35)0.416600.83 (0.59, 1.17)0.28210rs4624820rs4624820/rs68978765q31.1SPRY40.432A0.69 (0.56, 0.85)0.000470.89 (0.63, 1.28)0.54166rs474853rs38056635q31.1PITX10.4133A0.75 (0.60, 0.93)0.007601.03 (0.73, 1.45)0.87347exm-rs210138rs2101386p21.31BAK10.2445G1.71 (1.34, 2.20)0.000021.25 (0.88, 1.77)0.20662exm599133rs126994777p22.3MAD1L10.4092T1.28 (1.04, 1.58)0.019361.08 (0.76, 1.53)0.65794rs10275045rs102750457p22.3MAD1L10.4684T1.22 (0.99, 1.50)0.059871.10 (0.76, 1.57)0.61265rs6972549rs37788917p22.3MAD1L10.2905T0.95 (0.76, 1.20)0.683601.03 (0.73, 1.46)0.85882rs11986044rs70101628q13.3PRDM140.3228T0.76 (0.60, 0.97)0.023640.77 (0.54, 1.11)0.15983exm-rs7040024rs70400249p24.3DMRT10.2198A0.73 (0.56, 0.95)0.018100.81 (0.56, 1.17)0.26198rs7553831rs7553839p24.3DMRT10.2816T1.03 (0.81, 1.30)0.811701.33 (0.93, 1.90)0.12198exm-rs4474514rs447451412p22KITLG0.2043A0.76 (0.59, 0.99)0.040511.87 (1.29, 2.71)0.00085exm-rs995030rs99503012p22KITLG0.1964G0.80 (0.61, 1.05)0.102501.69 (1.16, 2.45)0.00603rs8046148rs804614816q12.1MFSD10.2074G0.69 (0.53, 0.89)0.003490.91 (0.63, 1.33)0.64298rs4888262rs488826216q22.3RFWD30.4993T0.92 (0.74, 1.13)0.420701.13 (0.79, 1.63)0.49973rs7221274rs722127417q22TEX14, RAD51C, PPM1E0.3606A0.92 (0.74, 1.13)0.422002.07 (1.43, 2.99)0.00008rs11656666rs990570417q22TEX14, RAD51C, PPM1E0.2699A0.85 (0.68, 1.07)0.174601.48 (1.05, 2.10)0.02651rs2250213rs283918621q22.3MCM3AP0.454A1.11 (0.90, 1.37)0.314600.87 (0.61, 1.23)0.43117 Citation Format: Erin L. Marcotte, Nathan Pankratz, James Amatruda, A. Lindsay Frazier, Mark Krailo, Stella Davies, Jacqueline Starr, Erica Langer, Caroline Hallstrom, Anthony Hooten, Jenny N. Poynter. Variants in BAK1 and SPRY4 are associated with pediatric germ cell tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-374.

Germ Cell Tumors in Adolescents and Young Adults.

Germ cell tumors (GCTs) represent a group of biologically complex malignancies that affect patients at different sites within the body and at different ages. The varying nature of these tumors reflects their cell of origin which is the primordial germ cell, which normally gives rise to ovarian and testicular egg and sperm producing cells. These cells retain an ability to give rise to all types of human tissues, and this is illustrated by the different kinds of GCTs that occur. In adolescent and young adult (AYA) patients, GCTs predominantly present as testicular, ovarian or mediastinal primary GCTs, and represent some of the most complex therapeutic challenges within any AYA practice. The varying types of GCTs, defined by primary site and/or age at presentation, can look very similar microscopically. However, there is growing evidence that they may have different molecular characteristics, different biology and different requirements for curative treatments. Whilst in adult testicular GCTs there is evidence for an environmental cause during fetal development and a genetic component, these causative factors are much less well understood in other GCTs. GCTs are some of the most curable cancers in adults, but some patients exhibit resistance to standard treatments. Because of this, today's clinical research is directed at understanding how to best utilize toxic therapies and promote healthy survivorship. This chapter explores the biology, behavior and treatment of GCTs and discusses how the AYA group of GCTs may hold some of the keys to understanding fundamental unanswered questions of biological variance and curability in GCTs.

Chromosome 12p abnormalities and IMP3 expression in prepubertal pure testicular teratomas

Although the histologic appearance of pure testicular teratomas (PTTs) is similar in children and adults, the prognosis is dramatically different. Prepubertal PTTs are rare, with a benign clinical course, whereas the adult cases typically have malignant outcomes. Chromosome 12p abnormalities are seen in most adult testicular germ cell tumors but have not been found in prepubertal PTTs. IMP3 is an oncofetal protein that is highly expressed in many malignancies. Recently, we demonstrated IMP3 is expressed in adult mature testicular teratomas but not in mature ovarian teratomas. The aim of this study was to evaluate prepubertal PTTs for chromosome 12p abnormalities and expression of IMP3. A total of 11 cases (excision, n=1; orchiectomy, n=10) were obtained from the surgical pathology archives of 2 large medical centers (1957-2013). All 11 cases were investigated for isochromosome 12p and 12p copy number gain using interphase fluorescence in situ hybridization analysis and were examined by immunohistochemistry for IMP3 expression. Patients ranged in age from 0.9 to 7.0 (mean, 2.4) years. A positive immunohistochemical stain for IMP3 (cytoplasmic staining) was identified in 5 (46%) of 11 cases. Isochromosome 12p was detected in 2 cases (18%) that also expressed IMP3. Somatic copy number alterations of 12p were not observed (0%). We are the first to describe 12p abnormalities and IMP3 expression in prepubertal PTTs. Our data demonstrate a small subset of PTTs harbor typical molecular alterations observed in adult testicular germ cell tumors. Although prepubertal PTTs are considered to be benign neoplasms, it may be a heterogeneous group.

Differential expression of IMP3 between male and female mature teratomas—immunohistochemical evidence of malignant nature

Ovarian mature teratoma is a benign tumour, whereas mature teratoma in adult testicular germ cell tumours (TGCTs) is considered to be a malignant tumour. IMP3, an oncofetal protein, plays an important role in embryogenesis and carcinogenesis. IMP3 has been demonstrated to be a malignant biomarker that is mainly expressed in malignant neoplasms rather than benign tissues. The aim of this study was to analyse IMP3 expression in germ cell tumours, and compare its expression between male and female teratomas. One hundred and seventy-eight cases (62 TGCTs, 52 ovarian teratomas, 27 metastatic testicular teratomas, and 37 cases of normal testicular tissue) obtained from the archives of two large academic medical centres were examined for IMP3 expression. Of the 62 TGCTs, 30 had mature teratoma components. IMP3 expression was present in 100% (30/30) of testicular mature teratoma components, and in 96% (26/27) of metastatic testicular teratomas. Other TGCT components also expressed IMP3 in 99% of cases (78/79). IMP3 expression was negative in all female mature teratomas. We describe for the first time an immunostaining marker that has differential expression in male and female mature teratomas, indicating that their pathogenesis differs. High expression of IMP3 in adult mature testicular teratomas supports their malignant nature.

Fatty acid synthase overexpression in adult testicular germ cell tumors: potential role in the progression of non-seminomatous germ cell tumors

Overexpression of fatty acid synthase (FASN), which is a key enzyme responsible for the endogenous synthesis of fatty acids, and its association with multistep progression have been demonstrated in various human malignant tumors. We aimed to clarify the potential role of FASN overexpression in the development and progression of adult testicular germ cell tumors (TGCTs). From the primary sites of a cohort of 113 TGCT cases, we obtained 221 histological components: 53 intratubular germ cell neoplasias, unclassified (IGCNUs), 84 seminomas, 32 embryonal carcinomas, seven choriocarcinomas, 21 yolk sac tumors, and 24 teratomas. Samples were analyzed for overexpression of FASN by immunohistochemistry. Intensities of immunoreactivity and the fraction of positive cells were classified into each four categories (intensity, 0 to 3; fraction, 0-10% = 1, 11-50% = 2, 51-80% = 3, and >80% = 4). The overall score was determined by multiplication of both scores and overall scores greater than 6 were considered FASN overexpression. On a component basis, FASN overexpression was detected in 8% of seminomas but not in IGCNUs (0%) and was detected frequently in non-seminomatous germ cell tumors (NSGCTs) (88% of embryonal carcinomas, all choriocarcinomas, 81% of yolk sac tumors, and 54% of teratomas). There were no cases of a mixed tumor (i.e., a tumor with multiple histological components) that overexpressed FASN in seminoma components but not in co-existing NSGCT components, suggesting sequential progression. Our immunohistochemical data suggest that FASN overexpression occurs as a late event during the progression from IGCNUs/seminomas to NSGCTs.

A comparison of pediatric, adolescent, and adult testicular germ cell malignancy

Testicular germ cell tumors (T-GCTs) occur from infancy to adulthood, and are the most common solid tumor in adolescent and young adult males. Traditionally, pediatric T-GCTs were perceived as more indolent than adult T-GCTs. However, there are few studies comparing these groups and none that specifically evaluate adolescents. An institutional database of T-GCT patients was reviewed and patients were categorized into Pediatric, aged 0-12 years, Adolescent, aged 13-19 years, and Adult, older than 20 years, cohorts. Demographics, tumor characteristics, disease stage, treatment, event-free survival (EFS), and overall survival (OS) were compared between groups. Overall, 413 patients (20 pediatric, 39 adolescent, 354 adult) met study criteria and were followed for a median of 2.0 years (0.1-23.6). Adolescents presented with more advanced stage than children (P = 0.018) or adults (P = 0.008). There was a higher rate of events in Adolescents (13, 33.3%) than in Adults (61, 17.2%) or Children (2, 10.0%). Three-year EFS was 87.2% in the Pediatric group, 59.9% in Adolescents and 80.0% in Adults (P = 0.011). In a multivariate analysis, controlling for stage, IGCCCG risk, and histology, the hazard ratio (HR) for an event was: 1 (Reference) for Adults, HR = 0.82 (95% CI 0.19-3.46; P = 0.33) for the Pediatric group, and HR = 2.22 (95% CI 1.21-4.07; P = 0.01) for Adolescents. Five-year OS was 100% in the Pediatric group, 84.8% in Adolescents, and 92.8% in Adults (P = 0.388). Lower EFS in adolescent T-GCT patients was observed than in either children or adults. Elucidating factors associated with inferior outcomes in adolescents is an important focus of future research.

Allelotyping analysis suggesting a consecutive progression from intratubular germ cell neoplasia to seminoma and then to embryonal carcinoma of the adult testis

Among adult testicular germ cell tumors, the pathogenesis of embryonal carcinoma remains a matter of debate. Some studies suggest a single consecutive progression from intratubular germ cell neoplasia, unclassified (IGCNU), to seminoma and then to embryonal carcinoma; others suggest that seminoma and embryonal carcinoma derive independently from IGCNU. This allelotyping study aimed to clarify the genetic relationship between embryonal carcinoma components and coexisting seminoma and/or IGCNU components. From a cohort of 18 patients with embryonal carcinoma, 11 coexisting seminoma components and 14 coexisting IGCNUs were identified. DNA isolated from each laser-microdissected tissue was subjected to polymerase chain reaction and loss of heterozygosity (LOH) analysis, using 20 polymorphic markers located on 12 chromosome arms (3q, 5q, 6p, 9p, 10q, 11p, 12p, 12q, 13q, 17p, 17q, and 18q). The concordance rate for allelic patterns was 82% between IGCNU and the coexisting seminoma components, 71% between IGCNU and the coexisting embryonal carcinoma components, and 80% between seminoma components and the coexisting embryonal carcinoma components. Estimation of probability indicated that these events were very unlikely to have occurred by chance. The total frequency of LOH increased progressively from IGCNU to seminoma and then to embryonal carcinoma, with statistically significant differences. In 7 cases with 3 histologic components, 28 chromosomal loci that showed LOH in the seminoma and embryonal carcinoma components were identified, and 15 (54%) retained heterozygosity in the coexisting IGCNUs. These findings suggest that a consecutive progression from IGCNU to seminoma, and ultimately, to embryonal carcinoma mainly occurred in the testicular germ cell tumor cases.

Altered expression of p27Kip1‐interacting cell‐cycle regulators in the adult testicular germ cell tumors: potential role in tumor development and histological progression

We examined the potential role of cell-cycle dysregulation in the development and histological progression of adult testicular germ cell tumors (TGCTs). Expressions of p27(Kip1) -interacting cell-cycle regulators (down-regulation of p27(Kip1) and overexpression of Skp2, Cks1, cyclin A, and cyclin E) and Ki-67 labeling index (LI) were immunohistochemically examined in histological components of 50 intratubular germ cell neoplasms, unclassified (IGCNUs); 74 seminomas; and 25 embryonal carcinomas, identified from 88 patients. Altered expression of p27(Kip1) , Skp2, Cks1, cyclin A, and cyclin E was observed in 20%, 12%, 16%, 10%, and 24% of IGCNUs; 26%, 36%, 27%, 89%, and 23% of seminomas; and 48%, 68%, 56%, 100%, and 60% of embryonal carcinomas, respectively. A significant difference in the frequency of Skp2 and cyclin A overexpression was observed between IGCNUs and seminomas. Significantly more frequent alterations of Skp2, Cks1, and cyclin E and p27(Kip1) were detected in embryonal carcinomas than in seminomas. Alterations of all cell-cycle regulators were significantly more frequent in embryonal carcinomas than in IGCNUs. The mean Ki-67 LI significantly increased from IGCNU (21.2%) through seminoma (34.7%) to embryonal carcinoma (54.2%). These results suggest that alterations of the p27(Kip1) -interacting cell-cycle regulators are common in TGCTs and may be involved in their histological progression.

Associations between variants in KITLG, SPRY4, BAK1, and DMRT1 and pediatric germ cell tumors

Recent genome wide association studies have identified susceptibility loci for adult testicular germ cell tumors (GCT) near KITLG, SPRY4, BAK1, and DMRT1. We evaluated variants in these four genes to determine whether these are also susceptibility loci for pediatric GCTs. DNA was isolated from 52 pediatric GCTs (ages 0-21 years) obtained from the Cooperative Human Tissue Network. Control DNA was isolated from de-identified dried blood spots from 141 white newborns. Genotyping was conducted using TaqMan assays (rs4474514) or by PCR and sequencing (rs4324715, rs210138, and rs755383). Associations between variants and GCT were evaluated using logistic regression with adjustment for sex. We also evaluated whether the associations differed by age at GCT diagnosis (0-9 years, 10-21 years), sex, and tumor location (gonadal, non-gonadal). We observed a significant association for rs210138 (BAK1) and pediatric GCT overall (odds ratio (OR) = 1.80, 95% confidence interval (CI) 1.10-2.95, P = 0.02) with non-significant associations similar in magnitude in both the pediatric (P = 0.09) and adolescent (P = 0.06) age groups. The KITLG (rs4474514) and SPRY4 (rs4324715) variants were significantly associated with GCT only in the adolescent age group (rs4474514: OR = 2.28, 95% CI 1.09-4.79, P = 0.03 and rs4324715: OR = 2.40, 95% CI 1.19-4.83, P = 0.01). Associations were mostly similar when stratified by sex. This is the first study to suggest that these loci may also be important in susceptibility to GCTs in the adolescent (KITLG, SPRY4, and BAK1) and pediatric (BAK1) age groups.

Protein overexpression and gene amplification of epidermal growth factor receptor in adult testicular germ cell tumors: Potential role in tumor progression

Little is known about the pathologic significance of epidermal growth factor receptor (EGFR) expression in malignant testicular germ cell tumors (TGCTs) in adults. From the primary tumor sites of a cohort of 110 TGCT cases, we obtained 209 histologically distinct components: 53 intratubular germ cell neoplasia unclassified (IGCNU) lesions, 83 seminomas (66 pure-form seminomas and 17 seminoma components in the mixed-form with nonseminomatous TGCTs), 27 embryonal carcinomas, eight choriocarcinomas, 18 yolk sac tumors, and 20 immature teratomas. Samples were analyzed for expression of EGFR protein and EGFR gene amplification by immunohistochemistry and fluorescence in situ hybridization (FISH), respectively. Overexpression of the EGFR protein was detected in 28% of seminomas (27% in the pure-form and 29% in the mixed-form), 11% of embryonal carcinomas, 88% of choriocarcinomas, 44% of yolk sac tumors, and none of the IGCNU lesions or immature teratomas. A higher copy number (≥4 copies per cell) and amplification of the EGFR gene were detected in 20% and 10% of seminomas, 13% and 0% of embryonal carcinomas, 71% and 60% of choriocarcinomas, 15% and 8% of yolk sac tumors, and none of the IGCNU lesions or immature teratomas, respectively. Both higher copy number and amplification of the EGFR gene were positively correlated with immunohistochemical overexpression of EGFR protein (each P < 0.0001). These results suggest that overexpression of EGFR protein and increased copy number or amplification of the EGFR gene occur relatively frequently in primary TGCTs, and may play roles in the formation of invasive cancer and in the progression, especially morphological evolution, of tumors.

Family history of cancer and malignant germ cell tumors in children: A report from the Children’s Oncology Group

Family history of testicular cancer is an established risk factor for adult testicular germ cell tumors (GCT). We evaluated the association between family history of cancer and pediatric GCT in a Children's Oncology Group case-control study that included 274 GCT cases (195 female and 79 male) diagnosed < age 15 years and 418 controls frequency matched to cases on sex and age. Family history data were collected through telephone interviews with biological mothers and fathers and unconditional logistic regression was used to evaluate associations with GCT adjusting for potential confounders. A family history of cancer with onset < age 40 years was associated with a reduced risk of GCT among female cases (Odds Ratio (OR) = 0.50, 95% Confidence Interval (CI) 0.28-0.89) and an increased risk among male cases (OR = 2.56, 95% CI 1.02-6.44). Male cases were more likely to report family history of melanoma compared with male controls (OR = 4.65, 95% CI 1.40-15.4). There was an inverse association between family history of ovarian or uterine cancers and GCT in girls (OR = 0.46, 95% CI 0.22-0.96). These sex and cancer site specific associations should be confirmed in additional studies as they may provide clues to the etiology of pediatric GCT.

Pediatric Malignant Germ Cell Tumors Show Characteristic Transcriptome Profiles

Malignant germ cell tumors (GCT) of childhood are rare and heterogeneous neoplasms thought to arise from primordial germ cells. They vary substantially in their natural history and show important clinical differences from their adult counterparts. To address the biological basis for these observations, we have undertaken a comprehensive analysis of global gene expression patterns in pediatric malignant GCTs and compared these findings with published data on adult testicular GCTs (TGCT). Our study included 27 primary tumors and assessed the principal malignant histologic types of pediatric GCT, yolk sac tumor (YST; n = 18), and seminoma (n = 9). Analysis of Affymetrix U133A GeneChip data was performed using the statistical software environment R, including gene set enrichment analysis, with cross-validation at the RNA and protein level. Unsupervised analysis showed complete separation of YSTs and seminomas by global gene expression profiles and identified a robust set of 657 discriminatory transcripts. There was no segregation of tumors of the same histology arising at different sites or at different ages within the pediatric range. In contrast, there was segregation of pediatric malignant GCTs and adult malignant TGCTs, most notably for the YSTs. The pediatric seminomas were significantly enriched for genes associated with the self-renewing pluripotent phenotype, whereas the pediatric YSTs were significantly enriched for genes associated with a differentiation and proliferation phenotype. We conclude that histologic type is the key discriminator in pediatric malignant GCTs and that the observed clinical differences between malignant GCTs of children and adults are mirrored by significant differences in global gene expression.