Familial testicular cancer: a report of the UK family register, estimation of risk and an HLA class 1 sib-pair analysis

Adolescent and Young Adult Germ Cell Tumors: Epidemiology, Genomics, Treatment, and Survivorship

Innovations in the care of adolescent and young adult (AYA) germ cell tumors (GCTs) are needed for one of the most common AYA cancers for which treatment has not significantly changed for several decades. Testicular GCTs (TGCTs) are the most common cancers in 15- to 39-year-old men, and ovarian GCTs (OvGCTs) are the leading gynecologic malignancies in women younger than 25 years. Excellent outcomes, even in widely metastatic disease using cisplatin-based chemotherapy, can be achieved since Einhorn and Donohue's landmark 1977 study in TGCT. However, as the severity of accompanying late effects (ototoxicity, neurotoxicity, cardiovascular disease, second malignant neoplasms, nephrotoxicity, and others) has emerged, efforts to deintensity treatment and find alternatives to cisplatin have taken on new urgency. Current innovations include the collaborative design of clinical trials that accrue GCTs across all ages and both sexes, including adolescents (previously on pediatric trials), and OvGCT (previously on gynecologic-only trials). Joint trials accrue larger sample sizes at a faster rate and therefore evaluate new approaches more rapidly. These joint trials also allow for biospecimen collection to further probe GCT etiology and underlying mechanisms of tumor growth, thus providing new therapeutic options. This AYA approach has been fostered by The Malignant Germ Cell International Consortium, which includes over 115 GCT disease experts from pediatric, gynecologic, and genitourinary oncologies in 16 countries. Trials in development incorporate, to our knowledge, for the first time, molecular risk stratification and precision oncology approaches on the basis of specific GCT biology. This collaborative AYA approach pioneering successfully in GCT could serve as a model for impactful research for other AYA cancer types.

Familial aggregation of testicular cancer among early-onset cancer survivors. A prospective observational cohort data from Finland

Testicular cancer (TC) is the most common form of cancer in men aged 15-35 years. Familial risk for TC is among highest of all cancers.

MATERIAL AND METHODS

A prospective observational cohort of 9111 relatives in 2,188 families of early-onset TC patients, called probands, diagnosed at age ≤40 years in Finland between 1970 and 2012. Standardized incidence ratios (SIR) were used as measures of familial aggregation for early-onset (≤40 years) TC. Follow-up ended at diagnosis of TC, death or 31 December 2014 whichever earliest.

RESULTS

Among first-degree relatives of early-onset TCs, in all 12 early-onset TC cases (0.24%) were diagnosed over the follow-up; the SIR for any first-degree relative was 4.59 (95% confidence interval (CI): 2.37-8.01) and for brothers the SIR was 6.51 (95% CI 3.12-11.96).

DISCUSSION

Familial aggregation of TC shows substantial risk for early-onset TC among first-degree relatives of early-onset TC patients in Finland. This is important to acknowledge to avoid diagnostic delay especially of TC.

Genetics of testicular germ cell tumors

PURPOSE OF REVIEW

Understanding the molecular basis underlying testicular germ cell tumors (TGCTs) may help improve patient outcomes, particularly for patients with poorer risk or chemoresistant disease. Here, we review the major contemporary advances in elucidating TGCT genetics by discussing patterns of TGCT inheritance, recent genomic and transcriptomic discoveries in TGCT, and the role of genetics in predicting therapeutic resistance and in guiding treatment.

RECENT FINDINGS

In the absence of a major high-penetrance TGCT susceptibility gene, inheritance is likely driven by a complex polygenic model with considerable variation. The most common genomic alterations found in TGCTs include gains in chromosome 12p and mutations in KIT, KRAS, and NRAS, particularly in seminomas. Sensitivity to cisplatin-based chemotherapy likely relies on intact TP53, reciprocal loss of heterozygosity, and high mitochondrial priming. Targetable mutations are uncommon in TGCTs, however, posing a challenge for the development of effective personalized therapies. Consistent with the characteristically low tumor mutational burden, immune checkpoint inhibitors do not appear to be effective for most TGCTs.

SUMMARY

Refinements in next-generation sequencing techniques over the last few years have enabled considerable advances in elucidating the genomic, transcriptomic, and epigenetic landscape of TGCTs. Future efforts focused on developing novel treatment modalities are needed.

Update on epidemiologic considerations and treatment trends in testicular cancer

PURPOSE OF REVIEW

We aim to give an overview of the epidemiology and treatment trends of testicular germ cell tumors (TGCTs), with an emphasis on recent trends.

RECENT FINDINGS

The incidence of TGCT appears to be increasing, particularly in developed countries, although the reasons are not well understood. There is evidence of racial differences in predisposition to TGCT, with white men having highest risk and men of African or Asian descent having lower risk. In the United States, the incidence of TGCT among Hispanics appears to be rising most quickly. A recent genomic analysis indicates there is no highly penetrant major TGCT susceptibility gene. Incorporation of multidisciplinary care has led to excellent long-term cure rates; however, access to care and insurance remains barriers in young men. Recent treatment trends have centered on maximizing oncologic outcomes while minimizing long-term morbidity.

SUMMARY

Emerging population-level data provide critical insight into the evolving demographics of TGCT, which may allow for elucidation of biologic and environmental determinants of TGCT. Further, identification of socioeconomic barriers to excellent clinical outcomes will allow for targeted interventions to patients with unique demographic and socioeconomic considerations. Treatment trend analyses suggest that the field is moving toward minimizing treatment-related morbidity.

Family history of cancer and risk of paediatric and young adult's testicular cancer: A Norwegian cohort study

Background

The aim of this study was to examine the association of a family history of cancer with the risk of testicular cancer in young adults.

Methods

This is a prospective cohort study including 1,974,287 males born 1951–2015, of whom 2686 were diagnosed with TC before the age of 30.

Results

A history of TC in male relatives was significantly associated with a diagnosis of TC among children and young adults, including brothers (6.3-fold), sons (4.7-fold), fathers (4.4-fold), paternal uncles (2.0-fold) and maternal uncles (1.9-fold). Individuals with a father diagnosed with a carcinoma or sarcoma showed an elevated risk (1.1-fold and 1.8-fold, respectively). A family history of mesothelioma was positively associated with a risk of TC [(father (2.8-fold), mother (4.6-fold) and maternal uncles and aunt (4.4-fold)]. Elevated risks were also observed when siblings were diagnosed with malignant melanoma (1.4-fold). The risk of TC was also increased when fathers (11.1-fold), paternal (4.9-fold) and maternal uncles and aunts (4.6-fold) were diagnosed with malignant neuroepithelial-tumours.

Conclusion

We found an increased risk of TC among children and young adults with a family history of TC, carcinoma, mesothelioma, sarcoma, malignant melanoma and malignant neuroepithelial tumours. Hereditary cancer syndromes might underlie some of the associations reported in this study.

New insights into germ cell tumor genomics

BACKGROUND

Testicular germ cell tumors (GCTs) represent the most common malignancy in young men. While GCTs represent a model for curable solid tumors due to exquisite chemosensitivity, mortality for patients with GCT comprises the most life years lost for non-pediatric malignancies. Given limited options for patients with platinum-resistant disease, improved insight into GCT biology could identify novel therapeutic options for patients with platinum-resistant disease. Recent studies into molecular characteristics of both early stage and advanced germ cell tumors suggest a role for rationally targeted agents and potentially immunotherapy.

RECENT DEVELOPMENTS

Recent GWAS meta-analyses have uncovered additional susceptibility loci for GCT and provide further evidence that GCT risk is polygenic. Chromosome arm level amplifications and reciprocal loss of heterozygosity have been described as significantly enriched in GCT compared to other cancer types. Contemporary analyses confirm ubiquitous gain of isochromosome 12 and mutations in addition to previously described GCT-associated genes such as KIT and KRAS. Alterations within the TP53-MDM2 signal transduction pathway appear to be enriched among patients with platinum-resistant disease. Potentially actionable targets, including alterations in TP53-MDM2, Wnt/β-catenin, PI3K, and MAPK signaling, are present in significant proportions of patients with platinum-resistant disease and may be exploited as therapeutic options. Pre-clinical and early clinical data also suggest a potential role for immunotherapy among patients with GCTs.

CONCLUSION

Molecular characterization of GCT patients may provide biologic rationale for novel treatment options in patients with platinum-resistant disease.

Variants in BAK1, SPRY4, and GAB2 are associated with pediatric germ cell tumors: A report from the children's oncology group

Germ cell tumors (GCT) are a rare form of childhood cancer that originate from the primordial germ cell. Recent genome-wide association studies (GWAS) have identified susceptibility alleles for adult testicular GCT (TGCT). We test whether these SNPs are associated with GCT in pediatric and adolescent populations. This case-parent triad study includes individuals with GCT diagnosed between ages 0 and 19. We evaluated 26 SNPs from GWAS of adult TGCT and estimated main effects for pediatric GCT within complete trios (N = 366) using the transmission disequilibrium test. We used Estimation of Maternal, Imprinting and interaction effects using Multinomial modelling to evaluate maternal effects in non-Hispanic white trios and dyads (N = 244). We accounted for multiple comparisons using a Bonferroni correction. A variant in SPRY4 (rs4624820) was associated with reduced risk of GCT (OR [95% CI]: 0.70 [0.57, 0.86]). A variant in BAK1 (rs210138) was positively associated with GCT (OR [95% CI]: 1.70 [1.32, 2.18]), with a strong estimated effect for testis tumors (OR [95% CI]: 3.31 [1.89, 5.79]). Finally, a SNP in GAB2 (rs948662) was associated with increased risk for GCT (OR [95% CI]: 1.56 [1.20, 2.03]). Nominal associations (P < 0.05) were noted for eight additional loci. A maternal effect was observed for KITLG SNP rs4474514 (OR [95% CI]: 1.66 [1.21, 2.28]) and a paternal parent-of-origin effect was observed for rs7221274 (P = 0.00007), near TEX14, RAD51C, and PPM1E. We observed associations between SNPs in SPRY4, BAK1, and GAB2 and GCTs. This analysis suggests there may be common genetic risk factors for GCT in all age groups.

Testicular germ cell tumor genomics

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

SUMMARY

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.

The genomic landscape of testicular germ cell tumours: from susceptibility to treatment

The genomic landscape of testicular germ cell tumour (TGCT) can be summarized using four overarching hypotheses. Firstly, TGCT risk is dominated by inherited genetic factors, which determine nearly half of all disease risk and are highly polygenic in nature. Secondly KIT-KITLG signalling is currently the major pathway that is implicated in TGCT formation, both as a predisposition risk factor and a somatic driver event. Results from genome-wide association studies have also consistently suggested that other closely related pathways involved in male germ cell development and sex determination are associated with TGCT risk. Thirdly, the method of disease formation is unique, with tumours universally stemming from a noninvasive precursor lesion, probably of fetal origin, which lies dormant through childhood into adolescence and then eventually begins malignant growth in early adulthood. Formation of a 12p isochromosome, a hallmark of TGCT observed in nearly all tumours, is likely to be a key triggering event for malignant transformation. Finally, TGCT have been shown to have a distinctive somatic mutational profile, with a low rate of point mutations contrasted with frequent large-scale chromosomal gains. These four hypotheses by no means constitute a complete model that explains TGCT tumorigenesis, but advances in genomic technologies have enabled considerable progress in describing and understanding the disease. Further advancing our understanding of the genomic basis of TGCT offers a clear opportunity for clinical benefit in terms of preventing invasive cancer arising in young men, decreasing the burden of chemotherapy-related survivorship issues and reducing mortality in the minority of patients who have treatment-refractory disease.

Etiology and early pathogenesis of malignant testicular germ cell tumors: towards possibilities for preinvasive diagnosis

Malignant testicular germ cell tumors (TGCT) are the most frequent cancers in Caucasian males (20-40 years) with an 70% increasing incidence the last 20 years, probably due to combined action of (epi)genetic and (micro)environmental factors. It is expected that TGCT have carcinoma in situ(CIS) as their common precursor, originating from an embryonic germ cell blocked in its maturation process. The overall cure rate of TGCT is more than 90%, however, men surviving TGCT can present long-term side effects of systemic cancer treatment. In contrast, men diagnosed and treated for CIS only continue to live without these long-term side effects. Therefore, early detection of CIS has great health benefits, which will require an informative screening method. This review described the etiology and early pathogenesis of TGCT, as well as the possibilities of early detection and future potential of screening men at risk for TGCT. For screening, a well-defined risk profile based on both genetic and environmental risk factors is needed. Since 2009, several genome wide association studies (GWAS) have been published, reporting on single-nucleotide polymorphisms (SNPs) with significant associations in or near the genes KITLG, SPRY4, BAK1, DMRT1, TERT, ATF7IP, HPGDS, MAD1L1, RFWD3, TEX14, and PPM1E, likely to be related to TGCT development. Prenatal, perinatal, and postnatal environmental factors also influence the onset of CIS. A noninvasive early detection method for CIS would be highly beneficial in a clinical setting, for which specific miRNA detection in semen seems to be very promising. Further research is needed to develop a well-defined TGCT risk profile, based on gene-environment interactions, combined with noninvasive detection method for CIS.

Rare inactivating PDE11A variants associated with testicular germ cell tumors

Germline inactivating mutations of isoform 4 of phosphodiesterase (PDE) 11A (coded by the PDE11A gene) have been associated with familial adrenocortical tumors and familial testicular cancer. Testicular tissue is unique in expressing all four isoforms of PDE11A. In a prior candidate gene study of 94 familial testicular germ cell tumor (TGCT) subjects, we identified a significant association between the presence of functionally abnormal variants in PDE11A and familial TGCT risk. To validate this novel observation, we sequenced the PDE11A coding region in 259 additional TGCT patients (both familial and sporadic) and 363 controls. We identified 55 PDE11A variants: 20 missense, four splice-site, two nonsense, seven synonymous, and 22 intronic. Ten missense variants were novel; nine occurred in transcript variant 4 and one in transcript variant 3. Five rare mutations (p.F258Y, p.G291R, p.V820M, p.R545X, and p.K568R) were present only in cases and were significantly more common in cases vs controls (P=0.0037). The latter two novel variants were functionally characterized and shown to be functionally inactivating, resulting in reduced PDE activity and increased cAMP levels. In further analysis of this cohort, we focused on white participants only to minimize confounding due to population stratification. This study builds upon our prior reports implicating PDE11A variants in familial TGCT, provides the first independent validation of those findings, extends that work to sporadic testicular cancer, demonstrates that these variants are uncommonly but reproducibly associated with TGCT, and refines our understanding regarding which specific inactivating PDE11A variants are most likely to be associated with TGCT risk.

Diagnosis and Treatment of Testicular Cancer: A Clinician's Perspective

Testicular germ cell tumors (GCTs) include seminoma and nonseminoma. Chance of cure is excellent for clinical stage I disease regardless of whether adjuvant treatment or a surveillance strategy with treatment only for those who relapse is used. Risk of recurrence is greater in nonseminoma with evidence of lymphovascular invasion, but most can be salvaged with chemotherapy and survival rates remain high. This article outlines key pathologic and clinical considerations in clinical stage I seminoma, nonseminoma, advanced disease, and assessment of cancer of unknown primary as a potential GCT.

Analysis of POU5F1, c-Kit, PLAP, AP2γ and SALL4 in gonocytes of patients with cryptorchidism

Cryptorchidism is a risk factor for the development of testicular germ cell tumors (TGCTs). The most common type of TGCT in cryptorchidism is seminoma. The intratubular germ cell neoplasia unclassified (ITGCNU) is a histological pattern preceding the development of seminomas and non-seminomas. It was suggested that in patients with cryptorchidism, the gonocytes remained undifferentiated with pluripotent abilities expressing proteins like POU domain class 5 transcription factor 1 (POU5F1), tyrosine kinase receptor c-Kit, placental-like alkaline phosphatase (PLAP), the transcription factor AP2γ and sal-like protein 4 (SALL4) that confer to the gonocytes this ability and therefore make them susceptible to develop ITGCNU. The aim of the present study was to determine if the gonocytes of patients with cryptorchidism express POU5F1, c-Kit, PLAP, AP2γ and SALL4 proteins after their differentiation period. Based on this, we evaluated samples of testicular tissue from newborns to 16-year old subjects with or without cryptorchidism in search of POU5F1, c-Kit, PLAP, AP2γ and SALL4 using immunocytochemical method, the results of which were validated by RT-PCR. The results showed that control subjects witnessed a down-regulation in the expression of these five proteins in the first year of life, which eventually disappeared. On the other hand, it was determined that 21.6% (8/37) of the patients with cryptorchidism continued to express, at least, one of the proteins analyzed in this study after the second year of life. And only 5.4% (2/37) of the patients were positive to the five markers. These data sustain the proposed hypothesis that in cryptorchid patients, ITGCNU arises from gonocytes that fail in their differentiation process to spermatogonia with conservation of the proteins (POU5F1, c-Kit, PLAP, AP2γ and SALL4) that maintain pluripotency and undifferentiated characteristics and which are responsible for making the gonocytes susceptible to malignancy. However, we cannot guarantee that these patients present neoplastic transformation.

Prospectively Identified Incident Testicular Cancer Risk in a Familial Testicular Cancer Cohort

BACKGROUND

Human testicular germ cell tumors (TGCT) have a strong genetic component and a high familial relative risk. However, linkage analyses have not identified a rare, highly penetrant familial TGCT (FTGCT) susceptibility locus. Currently, multiple low-penetrance genes are hypothesized to underlie the familial multiple-case phenotype. The observation that two is the most common number of affected individuals per family presents an impediment to FTGCT gene discovery. Clinically, the prospective TGCT risk in the multiple-case family context is unknown.

METHODS

We performed a prospective analysis of TGCT incidence in a cohort of multiple-affected-person families and sporadic-bilateral-case families; 1,260 men from 140 families (10,207 person-years of follow-up) met our inclusion criteria. Age-, gender-, and calendar time-specific standardized incidence ratios (SIR) for TGCT relative to the general population were calculated using SEER*Stat.

RESULTS

Eight incident TGCTs occurred during prospective FTGCT cohort follow-up (versus 0.67 expected; SIR = 11.9; 95% CI, 5.1-23.4; excess absolute risk = 7.2/10,000). We demonstrate that the incidence rate of TGCT is greater among bloodline male relatives from multiple-case testicular cancer families than that expected in the general population, a pattern characteristic of adult-onset Mendelian cancer susceptibility disorders. Two of these incident TGCTs occurred in relatives of sporadic-bilateral cases (0.15 expected; SIR = 13.4; 95% CI, 1.6-48.6).

CONCLUSIONS

Our data are the first to indicate that despite relatively low numbers of affected individuals per family, members of both multiple-affected-person FTGCT families and sporadic-bilateral TGCT families comprise high-risk groups for incident testicular cancer.

IMPACT

Men at high TGCT risk might benefit from tailored risk stratification and surveillance strategies.

Nontesticular cancers in relatives of testicular germ cell tumor (TGCT) patients from multiple-case TGCT families

Testicular germ cell tumors (TGCT) exhibit striking familial aggregation that remains incompletely explained. To improve the phenotypic definition of familial TGCT (FTGCT), we studied an international cohort of multiple-case TGCT families to determine whether first-degree relatives of FTGCT cases are at increased risk of other types of cancer. We identified 1041 first-degree relatives of TGCT cases in 66 multiple-case TGCT families from Norway and 64 from the United States (combined follow-up of 31,556 person-years). We collected data on all cancers (except nonmelanoma skin cancers) reported by the family informant in these relatives, and we attempted to verify all reported cancer diagnoses through medical or cancer registry records. We calculated observed-to-expected (O/E) standardized incidence ratios, together with 95% confidence intervals (CI), for invasive cancers other than TGCT. We found no increase in risk of cancer overall (Norway O/E = 0.8; 95% CI: 0.6–1.1 and United States O/E = 0.9; 95% CI: 0.7–1.3). Site-specific analyses pooled across the two countries revealed a leukemia excess (O/E = 6.5; 95% CI: 3.0–12.3), deficit of female breast cancer (O/E = 0.0; 95% CI: 0.0–0.6) and increased risk of soft tissue sarcoma (O/E = 7.2; 95% CI: 2.0–18.4); in all instances, these results were based on small case numbers and statistically significant only in Norway. While limited by sample size and potential issues relating to completeness of cancer reporting, this study in multiple-case TGCT families does not support the hypothesis that cancers other than testis cancer contribute to the FTGCT phenotype.

Whole-exome sequencing reveals the mutational spectrum of testicular germ cell tumours

Testicular germ cell tumours (TGCTs) are the most common cancer in young men. Here we perform whole-exome sequencing (WES) of 42 TGCTs to comprehensively study the cancer's mutational profile. The mutation rate is uniformly low in all of the tumours (mean 0.5 mutations per Mb) as compared with common cancers, consistent with the embryological origin of TGCT. In addition to expected copy number gain of chromosome 12p and mutation of KIT, we identify recurrent mutations in the tumour suppressor gene CDC27 (11.9%). Copy number analysis reveals recurring amplification of the spermatocyte development gene FSIP2 (15.3%) and a 0.4 Mb region at Xq28 (15.3%). Two treatment-refractory patients are shown to harbour XRCC2 mutations, a gene strongly implicated in defining cisplatin resistance. Our findings provide further insights into genes involved in the development and progression of TGCT.

Ten-year experience with testicular cancer at a tertiary care hospital in a resource-limited setting: a single centre experience in Tanzania

BACKGROUND

Testicular cancers constitute major therapeutic challenges in resource-limited countries and still carry poor outcomes. There is a paucity of published data regarding testicular cancer in Tanzania, and Bugando Medical Centre in particular. This study describes the clinicopathological pattern, treatment outcome and challenges in the management of testicular cancer in our local setting.

METHODS

This was a retrospective study including all patients who had had histopathologically confirmed testicular cancer at Bugando Medical Centre between February 2004 and January 2014.

RESULTS

A total of 56 testicular cancer patients were enrolled in the study, representing 0.9% of all malignancies. The median age of patients at presentation was 28 years, with a peak incidence in the 21-to-30-year age group. A family history of testicular cancer was reported in four (5.4%) patients. A history of cryptorchidism was reported in six (10.7%) patients. Most patients (57.1%) presented late with an advanced stage of cancer. Testicular swelling was the main complaint in 48 (85.7%) patients. The right testis was involved in 67.9% of cases. Lymph node and distant metastases were documented in 10 (17.9%) and 12 (21.4%) patients, respectively. Histologically, 80.4% of patients had germ cell cancers, with seminoma accounting for 62.2% of cases. The most common surgical procedure was inguinal orchidectomy (77.4%). Adjuvant chemotherapy and radiotherapy were used in six (11.1%) and four (7.4%) patients, respectively. Eight (14.3%) patients died. The main predictors of mortality (P<0.001) were patient's age (>65 years), late presentation (>6 months), stage of disease, and presence of metastasis at time of diagnosis. The mean follow-up period was 22 months. At the end of five years, only 18 (37.5%) patients were available for follow-up and the overall 5-year survival rate was 22.2%. The main predictors of 5-year survival rate (P<0.001) were patients' age, stage of disease, and presence of lymph node and distant metastases.

CONCLUSIONS

Testicular cancers, though rare in our setting, still carries a poor prognosis. Late presentation, poverty, paucity of resources and the high cost of newer imaging and treatment modalities are major challenges to management. Better health funding and education regarding testicular self-examination is essential.

A review of cancer risk prediction models with genetic variants

Cancer risk prediction models are important in identifying individuals at high risk of developing cancer, which could result in targeted screening and interventions to maximize the treatment benefit and minimize the burden of cancer. The cancer-associated genetic variants identified in genome-wide or candidate gene association studies have been shown to collectively enhance cancer risk prediction, improve our understanding of carcinogenesis, and possibly result in the development of targeted treatments for patients. In this article, we review the cancer risk prediction models that have been developed for popular cancers and assess their applicability, strengths, and weaknesses. We also discuss the factors to be considered for future development and improvement of models for cancer risk prediction.

Androgen receptor polymorphisms and testicular cancer risk

Testicular cancer (TC) is currently the most common malignant solid tumour in Caucasian males aged 15-39 years. Epidemiological evidence suggests that its onset may be due to an imbalance in the action of steroidal sex hormones and their receptors. A faulty androgen receptor signalling pathway can, in fact, cause various male reproductive disorders. The androgen receptor (AR) gene has two polymorphic segments consisting of CAG and GGC repeats. The length of CAG repeats has been shown to affect the regulation of AR activity. In our study, we used fragment analysis to evaluate the AR gene repeats of 302 TC patients and 322 controls, to establish if there is any association between repeat number and TC. This study of the largest Italian caseload investigated to date highlighted three particularly significant aspects. First, a CAG repeat number of ≥25 may be considered a risk factor for the onset of TC, given its greater frequency in patients in comparison with controls. This difference became significant for the non-seminoma group. Second, men with CAG repeats below 21 or above 24 were found to have a, respectively, 50 and 76% higher risk of TC than those with CAG 21-24, suggesting that these too can be considered a risk factor for TC. Finally, stage II patients were more likely to have a CAG repeat number <21 or >24 than stage I patients.

A hierarchical frailty model for familial testicular germ-cell tumors

Using a 2-level hierarchical frailty model, we analyzed population-wide data on testicular germ-cell tumor (TGCT) status in 1,135,320 two-generational Norwegian families to examine the risk of TGCT in family members of patients. Follow-up extended from 1954 (cases) or 1960 (unaffected persons) to 2008. The first-level frailty variable was compound Poisson-distributed. The underlying Poisson parameter was randomized to model the frailty variation between families and was decomposed additively to characterize the correlation structure within a family. The frailty relative risk (FRR) for a son, given a diseased father, was 4.03 (95% confidence interval (CI): 3.12, 5.19), with a borderline significantly higher FRR for nonseminoma than for seminoma (P = 0.06). Given 1 affected brother, the lifetime FRR was 5.88 (95% CI: 4.70, 7.36), with no difference between subtypes. Given 2 affected brothers, the FRR was 21.71 (95% CI: 8.93, 52.76). These estimates decreased with the number of additional healthy brothers. The estimated FRRs support previous findings. However, the present hierarchical frailty approach allows for a very precise definition of familial risk. These FRRs, estimated according to numbers of affected/nonaffected family members, provide new insight into familial TGCT. Furthermore, new light is shed on the different familial risks of seminoma and nonseminoma.

Recent advances in molecular and cell biology of testicular germ-cell tumors

Testicular germ-cell tumors (TGCTs) are the most frequent solid malignant tumors in men 20-40 years of age and the most frequent cause of death from solid tumors in this age group. TGCTs comprise two major histologic groups: seminomas and nonseminomas germ-cell tumors (NSGCTs). NSGCTs can be further divided into embryonal, carcinoma, Teratoma, yolk sac tumor, and choriocarcinoma. Seminomas and NSGCTs present significant differences in clinical features, therapy, and prognosis, and both show characteristics of the primordial germ cells. Many discovered biomarkers including OCT3/4, SOX2, SOX17, HMGA1, Nek2, GPR30, Aurora-B, estrogen receptor β, and others have given further advantages to discriminate between histological subgroups and could represent useful novel molecular targets for antineoplastic strategies. More insight into the pathogenesis of TGCTs is likely to improve disease management not only to better treatment of these tumors but also to a better understanding of stem cells and oncogenesis.

Embryonic left-right separation mechanism allows confinement of mutation-induced phenotypes to one lateral body half of bilaterians

A fundamental question in developmental biology is how a chimeric animal such as a bilateral gynandromorphic animal can have different phenotypes confined to different lateral body halves, and how mutation-induced phenotypes, such as genetic diseases, can be confined to one lateral body half in patients. Here, I propose that embryos of many, if not all, bilaterian animals are divided into left and right halves at a very early stage (which may vary among different types of animals), after which the descendants of the left-sided and right-sided cells will almost exclusively remain on their original sides, respectively, throughout the remaining development. This embryonic left-right separation mechanism allows (1) mutations and the mutation-induced phenotypes to be strictly confined to one lateral body half in animals and humans; (2) mothers with bilateral hereditary primary breast cancer to transmit their disease to their offspring at twofold of the rate compared to mothers with unilateral hereditary breast cancer; and (3) a mosaic embryo carrying genetic or epigenetic mutations to develop into either an individual with the mutation-induced phenotype confined unilaterally, or a pair of twins displaying complete, partial, or mirror-image discordance for the phenotype. Further, this left-right separation mechanism predicts that the two lateral halves of a patient carrying a unilateral genetic disease can each serve as a case and an internal control, respectively, for genetic and epigenetic comparative studies to identify the disease causations.

Interaction between DMRT1 function and genetic background modulates signaling and pluripotency to control tumor susceptibility in the fetal germ line

Dmrt1 (doublesex and mab-3 related transcription factor (1) is a regulator of testis development in vertebrates that has been implicated in testicular germ cell tumors of mouse and human. In the fetal mouse testis Dmrt1 regulates germ cell pluripotency in a strain-dependent manner. Loss of Dmrt1 in 129Sv strain mice results in a >90% incidence of testicular teratomas, tumors consisting cells of multiple germ layers; by contrast, these tumors have never been observed in Dmrt1 mutants of C57BL/6J (B6) or mixed genetic backgrounds. To further investigate the interaction between Dmrt1 and genetic background we compared mRNA expression in wild type and Dmrt1 mutant fetal testes of 129Sv and B6 mice at embryonic day 15.5 (E15.5), prior to overt tumorigenesis. Loss of Dmrt1 caused misexpression of overlapping but distinct sets of mRNAs in the two strains. The mRNAs that were selectively affected included some that changed expression only in one strain or the other and some that changed in both strains but to a greater degree in one versus the other. In particular, loss of Dmrt1 in 129Sv testes caused a more severe failure to silence regulators of pluripotency than in B6 testes. A number of genes misregulated in 129Sv mutant testes also are misregulated in human testicular germ cell tumors (TGCTs), suggesting similar etiology between germ cell tumors in mouse and man. Expression profiling showed that DMRT1 also regulates pluripotency genes in the fetal ovary, although Dmrt1 mutant females do not develop teratomas. Pathway analysis indicated disruption of several signaling pathways in Dmrt1 mutant fetal testes, including Nodal, Notch, and GDNF. We used a Nanos3-cre knock-in allele to perform conditional gene targeting, testing the GDNF coreceptors Gfra1 and Ret for effects on teratoma susceptibility. Conditional deletion of Gfra1 but not Ret in fetal germ cells of animals outcrossed to 129Sv caused a modest but significant elevation in tumor incidence. Despite some variability in genetic background in these crosses, this result is consistent with previous genetic mapping of teratoma susceptibility loci to the region containing Gfra1. Using Nanos3-cre we also uncovered a strong genetic interaction between Dmrt1 and Nanos3, suggesting parallel functions for these two genes in fetal germ cells. Finally, we used chromatin immunoprecipitation (ChIP-seq) analysis to identify a number of potentially direct DMRT1 targets. This analysis suggested that DMRT1 controls pluripotency via transcriptional repression of Esrrb, Nr5a2/Lrh1, and Sox2. Given the strong evidence for involvement of DMRT1 in human TGCT, the downstream genes and pathways identified in this study provide potentially useful candidates for roles in the human disease.

Testicular germ cell tumor susceptibility associated with the UCK2 locus on chromosome 1q23

Genome-wide association studies (GWASs) have identified multiple common genetic variants associated with an increased risk of testicular germ cell tumors (TGCTs). A previous GWAS reported a possible TGCT susceptibility locus on chromosome 1q23 in the UCK2 gene, but failed to reach genome-wide significance following replication. We interrogated this region by conducting a meta-analysis of two independent GWASs including a total of 940 TGCT cases and 1559 controls for 122 single-nucleotide polymorphisms (SNPs) on chromosome 1q23 and followed up the most significant SNPs in an additional 2202 TGCT cases and 2386 controls from four case-control studies. We observed genome-wide significant associations for several UCK2 markers, the most significant of which was for rs3790665 (PCombined = 6.0 × 10(-9)). Additional support is provided from an independent familial study of TGCT where a significant over-transmission for rs3790665 with TGCT risk was observed (PFBAT = 2.3 × 10(-3)). Here, we provide substantial evidence for the association between UCK2 genetic variation and TGCT risk.

Current management of testicular cancer

Germ cell tumors (GCTs) of the testis are rare, but are the most common cancer in young men. GCTs may consist of one predominant histologic pattern or may represent a mixture of multiple histologic types. For treatment purposes, two broad categories are recognized: 1) pure seminoma and 2) others, which together are termed nonseminomatous GCTs (NSGCTs). In general, seminoma tends to be less aggressive, to be diagnosed at an earlier stage, and to spread predictably along lymphatic channels to the retroperitoneum before spreading hematogenously to the lung or other organs. Compared with NSGCTs, seminoma is exquisitely sensitive to radiation therapy and platinum-based chemotherapy. NSGCTs are usually mixed tumors and teratoma often exists at the sites of metastasis with other GCT elements; cure often requires chemotherapy to kill the chemosensitive-components and surgery to remove the teratomatous components. The main factors contributing to excellent cure rates of GCTs are careful staging at diagnosis; adequate early treatment using chemotherapeutic combinations, with or without radiotherapy and surgery; and very strict follow-up and salvage therapy. We review several clinical studies and summarize the current trends in the management of GCTs.

Genomic characterization of testis cancer: association of alterations with outcome of clinical stage 1 mixed germ cell nonseminomatous germ cell tumor of the testis

OBJECTIVE

To identify genomic markers that are reliable in predicting lymph node metastases in clinical stage 1 non-seminomatous germ cell tumors (NSGCTs).

METHODS

Comparative genomic array technology was used to identify regions of genomic amplification or deletion in clinical stage 1 NSGCTs. Twelve stage 1 mixed germ cell testicular tumors were analyzed, which were obtained from 8 patients who had no evidence of nodal metastasis when retroperitoneal lymph node dissection (RPLND) had been performed (ie, were RPLND negative) and 4 patients who had nodal metastases (ie, were RPLND positive).

RESULTS

Differences between the genomic alterations associated with the two classes of tumors were identified. Genomic alterations previously reported in other subtypes of testicular tumors were observed in both metastatic and nonmetastatic cases. Statistically suggestive differences in mean copy number of the Y chromosome were found between metastatic and nonmetastatic cases (P = .0142).

CONCLUSION

This finding suggests the presence of chromosome Y deletions to be a potential genetic marker for prediction of mixed germ cell tumor progression. This is a first step toward identifying chromosomal markers of progression in testicular cancer in clinical stage 1 mixed germ cell NSGCT.

A stratified genetic risk assessment for testicular cancer

Three genome-wide association studies of testicular cancer have uncovered predisposition alleles in or near KITLG, BAK1, SPRY4, TERT, ATF7IP and DMRT1. We investigated whether testicular cancer-risk alleles can be utilized in the clinical setting. We employed the receiver operating characteristic curves for genetic risk models to measure the discriminatory power of a risk variant-based risk model, and found that the newly discovered variants provided a discriminatory power of 69.2%. This suggested that about 69.2% of the time, a randomly selected patient with testicular cancer had a higher estimated risk than the risk for a randomly selected control subject. Using a multiplicative model, we estimated that white men in the top 1% of genetic risk as defined by eight risk variants had a relative risk that was 10.5-fold greater than that for the general white male population. This risk differential does not appear to be clinically useful, given the relative rarity and highly curable nature of testicular germ cell tumour (TGCT). In the authors' view, a stratified genetic risk assessment strategy might be useful, theoretically, for men who also have independent clinical risk factors for testicular cancer. Several established TGCT risk factors, such as cryptorchidism (RR=4.8) and male infertility (SIR=2.8) might prove useful in that context, but we currently do not know whether these testicular cancer-risk loci are associated with, or independent of, such clinical risk factors. More research is required before we can utilize testicular cancer-risk loci for clinically meaningful risk prediction.

Heterogenous effect of androgen receptor CAG tract length on testicular germ cell tumor risk: shorter repeats associated with seminoma but not other histologic types

Increasing rates of testicular germ cells tumors (TGCTs) overtime suggest that environmental factors are involved in disease etiology, but familial risk and genome-wide association studies implicate genetic factors as well. We investigated whether variation in the functional CAG(n) polymorphism in the androgen receptor (AR) gene is associated with TGCT risk, using data from a population-based family study. We estimated odds ratios (OR) and 95% confidence intervals (CI) for the association of CAG repeat length and TGCT risk using matched pairs logistic regression. Analyses of 273 TGCT case-mother pairs revealed no association between AR CAG repeat length and overall TGCT risk. However, risk of seminoma was significantly associated with shorter CAG repeat length [CAG 20-21 versus CAG ≤ 19: OR = 0.82 (95% CI: 0.43-1.58), CAG 22-23 versus CAG ≤ 19: OR = 0.39 (95% CI: 0.19-0.83) and CAG ≥ 24 versus CAG ≤ 19: OR = 0.42 (95% CI: 0.20-0.86)], with a highly significant trend over these four categories of decreasing CAG repeat length (P(trend) = 0.0030). This is the first report of a statistically significant association between AR CAG repeat length and seminoma risk, suggesting that increased AR transactivation may be involved in development of seminoma and/or progression of carcinoma in situ/intratubular germ cell neoplasia unclassified to seminoma. This result provides a rationale whereby androgenic environmental compounds could contribute to increases in TGCT incidence, and identifies for the first time a potential biological pathway influencing whether TGCTs achieve seminomatous versus nonseminomatous histology, a clinically and biologically important distinction.

Genome-wide association studies provide new insights into the genetic basis of testicular germ-cell tumour

Testicular germ-cell tumour (TGCT) is the most common cancer in young men, and genetic epidemiological studies suggest that the disease has a strong genetic basis. Until 2009, very little of this genetic component had been explained. Genome-wide association studies have since identified eight SNPs at six loci which together account for approximately 15% of the genetic risk of TGCT and offer novel biological insights into testicular germ-cell oncogenesis. In this review, we summarize the genetic epidemiology of TGCT, detail the contribution genome-wide association studies have made to our understanding of the genetic basis of TGCT and reflect on how future technological advances may assist in revealing the remaining genetic factors underlying TGCT susceptibility.

A second independent locus within DMRT1 is associated with testicular germ cell tumor susceptibility

Susceptibility to testicular germ cell tumors (TGCT) has a significant heritable component, and genome-wide association studies (GWASs) have identified association with variants in several genes, including KITLG, SPRY4, BAK1, TERT, DMRT1 and ATF7IP. In our GWAS, we genotyped 349 TGCT cases and 919 controls and replicated top hits in an independent set of 439 cases and 960 controls in an attempt to find novel TGCT susceptibility loci. We identified a second marker (rs7040024) in the doublesex and mab-3-related transcription factor 1 (DMRT1) gene that is independent of the previously described risk allele (rs755383) at this locus. In combined analysis that mutually conditions on both DMRT1 single nucleotide polymorphism markers, TGCT cases had elevated odds of carriage of the rs7040024 major A allele [per-allele odds ratio (OR) = 1.48, 95% confidence interval (CI) 1.23, 1.78; P = 2.52 × 10(-5)] compared with controls, while the association with rs755383 persisted (per allele OR = 1.26, 95% CI 1.08, 1.47, P = 0.0036). In similar analyses, the association of rs7040024 among men with seminomatous tumors did not differ from that among men with non-seminomatous tumors. In combination with KITLG, the strongest TGCT susceptibility locus found to date, men with TGCT had greatly elevated odds (OR = 14.1, 95% CI 5.12, 38.6; P = 2.98 × 10(-7)) of being double homozygotes for the risk (major) alleles at DMRT (rs7040024) and KITLG (rs4474514) when compared with men without TGCT. Our findings continue to corroborate that genes influencing male germ cell development and differentiation have emerged as the major players in inherited TGCT susceptibility.

Testicular germ cell tumours: predisposition genes and the male germ cell niche

Testicular germ cell tumours (TGCTs) of adults and adolescents are putatively derived from primordial germ cells or gonocytes. Recently reported genome-wide association studies implicate six gene loci that predispose to TGCT development. Remarkably, the functions of proteins encoded by genes within these regions bridge our understanding between the pathways involved in primordial germ cell physiology, male germ cell development and the molecular pathology of TGCTs. Furthermore, this improved understanding of the mechanisms underlying TGCT development and dissemination has clinical relevance for the management of patients with these tumours.

Cancer in first-degree relatives and risk of testicular cancer in Denmark

Familial aggregation of testicular cancer has been reported consistently, but it is less clear if there is any association between risk of testicular cancer and other cancers in the family. We conducted a population-based case-control study to examine the relationship between risk of testicular cancer and 22 different cancers in first-degree relatives. We included 3,297 cases of testicular cancer notified to the Danish Cancer Registry between 1991 and 2003. A total of 6,594 matched controls were selected from the Danish Civil Registration System, which also provided the identity of 40,104 first-degree relatives of case and controls. Familial cancer was identified by linkage to the Danish Cancer Registry, and we used conditional logistic regression to analyze whether cancer among first-degree relatives was associated with higher risk of testicular cancer. Rate ratio for testicular cancer was 4.63 (95% CI: 2.41-8.87) when a father, 8.30 (95% CI: 3.81-18.10) when a brother and 5.23 (95% CI: 1.35-20.26) when a son had testicular cancer compared to no familial testicular cancer. Results were similar when analyses were stratified by histologic subtypes of testicular cancer. Familial non-Hodgkin lymphoma and esophageal cancer were associated with testicular cancer; however, these may be chance findings. The familial aggregation of testicular and possibly other cancers may be explained by shared genes and/or shared environmental factors, but the mutual importance of each of these is difficult to determine.

X-linked tumor suppressors: perplexing inheritance, a unique therapeutic opportunity

Unlike autosomal genes, the majority of X-linked genes are subject to dosage compensation. As a result, female tissues comprise cells exclusively expressing X-linked genes from one or other parent. The implication of having only one allele of active X-linked genes in cancer pathogenesis, i.e. somatic single-hit inactivation and dominant inheritance, has not been extensively explored. Recent studies have identified FOXP3 and WTX as two X-linked tumor suppressor genes that are somatically inactivated by single genetic hits. Because the predicted dominant inheritance of cancer risk has not been demonstrated in humans, we will discuss the possible conditions that might prevent such dominant inheritance. We also argue that the existence of a genetically intact allele in cancer cells in women, together with apparent abnormal X inactivation in cancer cells, might provide an opportunity to selectively reactivate tumor suppressor genes for cancer therapy.

Functional glutathione S-transferase genotypes among testicular germ cell tumor survivors: associations with primary and post-chemotherapy tumor histology

PURPOSE

The pathogenesis of testicular germ cell tumor (TGCT) remains unknown. The aim of this study was to evaluate the pathogenic role of functional polymorphisms in detoxification enzymes among TGCT patients, through association studies of constitutive genotypes and medical parameters before and after chemotherapy.

EXPERIMENTAL DESIGN

Germline deletion polymorphisms in the glutathione S-transferase mu 1 (GSTM1) and the GST theta 1 (GSTT1), and a functional single nucleotide polymorphism in GST pi 1 (GSTP1, Ile105Val), were analyzed in TGCT survivors (TCSs) (n = 675) and controls (n = 189). Statistical analyses were performed for the genotype distributions between the TCSs and control populations, and between the genotypes and clinicopathological parameters of the TCSs.

RESULTS

The GST genotypes showed comparable distributions among the TCSs and the control population. However, the genotype combination GSTT1positive/GSTP1-GG or GSTP1-AG/GSTM1positive was more frequent among the TCSs [P = 0.050, odds ratio (OR): 1.47, 95% confidence interval (CI): 0.998-2.165]. The combined genotype GSTT1positive/GSTP1AA/GSTM1positive was associated with decreased risk of development of pure embryonal carcinoma (P = 0.009, OR: 0.309, 95% CI: 0.122-0.784) and the GSTP1-A-allele (i.e. genotypes GSTP-AA or GSTP-AG) was also associated with decreased risk for development of pure teratoma (P = 0.032, OR: 0.326, 95% CI: 0.122-0.873). Furthermore, the GSTP1-A-allele was overrepresented within the 'good prognosis group' (P = 0.032, OR: 2.407, 95% CI: 1.060-5.469), whereas the GSTM1nulltype was associated with the extent of TC qualifying as 'poor prognosis group' (P = 0.025, OR: 2.839, 95% CI: 1.104-7.301). The GSTP1-AG genotype was associated with necrosis in the tumor's post-chemotherapy histology (P = 0.001, OR: 16.087, 95% CI: 1.930-134.087). Failure, after platinum-based chemotherapy, was associated with the GSTT1positive/GSTP-AA or GSTP-GG/GSTM1-positive genotype (P = 0.019, OR: 2.168, 95% CI: 1.130-4.160).

CONCLUSION

This study confirms an association between the GSTP1-G-allele and TGCT. Combinations of GST genotypes were associated with primary and post-chemotherapy tumor histology, and prognostic group presentation.

Transgenerational genetic effects on phenotypic variation and disease risk

Traditionally, we understand that individual phenotypes result primarily from inherited genetic variants together with environmental exposures. However, many studies showed that a remarkable variety of factors including environmental agents, parental behaviors, maternal physiology, xenobiotics, nutritional supplements and others lead to epigenetic changes that can be transmitted to subsequent generations without continued exposure. Recent discoveries show transgenerational epistasis and transgenerational genetic effects where genetic factors in one generation affect phenotypes in subsequent generation without inheritance of the genetic variant in the parents. Together these discoveries implicate a key signaling pathway, chromatin remodeling, methylation, RNA editing and microRNA biology. This exceptional mode of inheritance complicates the search for disease genes and represents perhaps an adaptation to transmit useful gene expression profiles from one generation to the next. In this review, I present evidence for these transgenerational genetic effects, identify their common features, propose a heuristic model to guide the search for mechanisms, discuss the implications, and pose questions whose answers will begin to reveal the underlying mechanisms.

Genetic factors on mouse chromosome 18 affecting susceptibility to testicular germ cell tumors and permissiveness to embryonic stem cell derivation

Despite strong heritability, little is known about the genetic control of susceptibility to testicular germ cell tumors (TGCT) in humans or mice. Although the mouse model of spontaneous TGCTs has been extensively studied, conventional linkage analysis has failed to locate the factors that control teratocarcinogenesis in the susceptible 129 family of inbred strains. As an alternative approach, we used both chromosome substitution strains (CSS) to identify individual chromosomes that harbor susceptibility genes and a panel of congenic strains derived from a selected CSS to determine the number and location of susceptibility variants on the substituted chromosome. We showed that 129-Chr 18(MOLF) males are resistant to spontaneous TGCTs and that at least four genetic variants control susceptibility in males with this substituted chromosome. In addition, early embryonic cells from this strain fail to establish embryonic stem cell lines as efficiently as those from the parental 129/Sv strain. For the first time, 129-derived genetic variants that control TGCT susceptibility and fundamental aspects of embryonic stem cell biology have been localized in a genetic context in which the genes can be identified and functionally characterized.

Metachronous testicular teratoma, testicular seminoma and papillary thyroid carcinoma occurring in a single individual: a report of two unrelated cases

We describe two unrelated men who both developed teratomas in one testis followed by seminomas in the contralateral testis followed by papillary thyroid carcinomas. Neither man had a family history of cancers. Although random occurrence is possible, genetic predisposition and/or environmental influence would seem a likely explanation for this previously unreported combination of tumours.

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.

Quality of care for testis cancer

This article explores the delivery of high quality care in patients with testicular cancer. Critical issues relate to an individualized, risk-stratified, and multidisciplinary approach to patient care at centers of excellence and subsequent close patient follow-up. The necessary integration of multiple therapeutic modalities makes testis cancer outcomes highly susceptible to variations in quality of care, which deserves further investigation in well designed population-based studies.

Younger age-at-diagnosis for familial malignant testicular germ cell tumor

One of the clinical hallmarks of hereditary cancer susceptibility disorders is a younger-than-usual age at diagnosis. Familial aggregation of testicular germ cell tumor (TGCT) has been reported, but data on whether familial TGCT cases are diagnosed at an earlier age are inconclusive. Here we compared the age at diagnosis of familial TGCT cases with that of population cases in several countries. Familial TGCT is defined as affected individuals from families with >or=2 cases of TGCT. Age at diagnosis of familial cases from the United States, Canada, United Kingdom, Australia and New Zealand, Norway, and Hungary was compared to cases identified in population-based cancer registries from the respective country, using the generalized estimation equation method. Age at diagnosis was statistically significantly younger for familial TGCT cases from North America (P = 0.024), the United Kingdom (P < 0.0001), and Australia and New Zealand (P = 0.0033) compared with population cases. When stratified by histology, the difference in age at diagnosis distribution between familial and population cases was observed for seminoma cases from North America (P = 0.002) and the United Kingdom (P < 0.0001) and non-seminoma cases from the United Kingdom (P = 0.029) and Australia and New Zealand (P = 0.0023). In summary, we found that the age at diagnosis for familial TGCT cases is, on the average, 2-3 years younger than that for the population cases in North America, United Kingdom, and Australia and New Zealand. The younger age at diagnosis might be suggestive of a genetic basis for familial TGCT.

A genome-wide association study of testicular germ cell tumor

We conducted a genome-wide association study for testicular germ cell tumor (TGCT), genotyping 307,666 SNPs in 730 cases and 1,435 controls from the UK and replicating associations in a further 571 cases and 1,806 controls. We found strong evidence for susceptibility loci on chromosome 5 (per allele OR = 1.37 (95% CI = 1.19-1.58), P = 3 x 10(-13)), chromosome 6 (OR = 1.50 (95% CI = 1.28-1.75), P = 10(-13)) and chromosome 12 (OR = 2.55 (95% CI = 2.05-3.19), P = 10(-31)). KITLG, encoding the ligand for the receptor tyrosine kinase KIT, which has previously been implicated in the pathogenesis of TGCT and the biology of germ cells, may explain the association on chromosome 12.

Functional phosphodiesterase 11A mutations may modify the risk of familial and bilateral testicular germ cell tumors

Inactivating germline mutations in phosphodiesterase 11A (PDE11A) have been implicated in adrenal tumor susceptibility. PDE11A is highly expressed in endocrine steroidogenic tissues, especially the testis, and mice with inactivated Pde11a exhibit male infertility, a known testicular germ cell tumor (TGCT) risk factor. We sequenced the PDE11A gene-coding region in 95 patients with TGCT from 64 unrelated kindreds. We identified 8 nonsynonymous substitutions in 20 patients from 15 families: four (R52T, F258Y, G291R, and V820M) were newly recognized, three (R804H, R867G, and M878V) were functional variants previously implicated in adrenal tumor predisposition, and one (Y727C) was a known polymorphism. We compared the frequency of these variants in our patients to unrelated controls that had been screened and found negative for any endocrine diseases: only the two previously reported variants, R804H and R867G, known to be frequent in general population, were detected in these controls. The frequency of all PDE11A-gene variants (combined) was significantly higher among patients with TGCT (P = 0.0002), present in 19% of the families of our cohort. Most variants were detected in the general population, but functional studies showed that all these mutations reduced PDE activity, and that PDE11A protein expression was decreased (or absent) in TGCT samples from carriers. This is the first demonstration of the involvement of a PDE gene in TGCT, although the cyclic AMP signaling pathway has been investigated extensively in reproductive organ function and their diseases. In conclusion, we report that PDE11A-inactivating sequence variants may modify the risk of familial and bilateral TGCT.

[Molecular pathology of testicular germ cell tumors: an update]

Germ cell tumors (GCT) comprise a heterogeneous group of benign and malignant tumors. Based on their different biological characteristics and their origin, five types of GCT are classified. Among these, malignant seminomatous and non-seminomatous GCT in males and females are designated as type II GCT. They occur most frequently as malignant testicular GCTs. Many characteristics of type II GCT can be linked to embryonic stem cells. Intratubular germ cell neoplasia, unclassified (IGCNU) is the precursor of type II GCT and derives from undifferentiated germ cells, gonocytes, which persist in the newborn testis and escape the normal differentiation process. It is suggested that Exon-17-activated mutations of the receptor tyrosine kinase, c-KIT, occur early in germ cell development and that gonocytes with an activated c-KIT receptor are restricted in their differentiation, thereby escaping normal development. New diagnostic markers for neoplastic germ cells, including OCT3/4 and AP-2gamma, are specifically detected in IGCNU, seminomas and embryonal carcinomas and are helpful in the differentiation of type II GCT from other malignant tumors.

The role of the mouse y chromosome on susceptibility to testicular germ cell tumors

Testicular germ cell tumors (TGCT) are sex limited, occurring only in males with a Y chromosome. Recently, the gr/gr deletion on the human Y chromosome was associated with increased risk of TGCTs. In addition, the presence of Y chromosome sequences is associated with TGCTs in cases of gonadal dysgenesis. TGCTs in strain 129 males recapitulate many aspects of testicular cancer in human infants and can be used to evaluate the role of the Y chromosome in TGCT risk. We used chromosome substitution strains and a sex-reversing mutant to test the role of the Y chromosome on TGCT susceptibility. Our results show that a Y-linked gene that does not differ among the tested strains is essential for tumorigenesis.

Biology of testicular germ cell tumors

Germ cell tumors are derived from cells of the germ cell lineage and are the most common solid malignancies to affect young Caucasian men between the ages of 15 and 40 years. All testicular germ cell tumors develop from the same precursor lesion, intratubular germ cell neoplasia unclassified, which in turn is thought to arise from malignant transformation of a primordial germ cell or gonocyte. These tumors are characterized by extreme chemosensitivity and are considered a model for curative disease. In spite of this, a small subset of patients with metastatic disease fail to achieve a complete response with cisplatin-based chemotherapy or relapse from complete remission. Understanding the molecular biology may help the design of new therapies for those patients with a poor prognosis and could also improve the treatment of cancer in general. Current understanding of the role of genetic and epigenetic factors in the etiology of germ cell tumors and the biochemical mechanisms underlying chemotherapy sensitivity and resistance is discussed in detail in this review.