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.

The International Testicular Cancer Linkage Consortium: a clinicopathologic descriptive analysis of 461 familial malignant testicular germ cell tumor kindred

OBJECTIVES

Familial aggregation of testicular germ cell tumor (TGCT) has been reported, but it is unclear if familial TGCT represents a unique entity with distinct clinicopathologic characteristics. Here we describe a collection of familial TGCT cases from an international consortium, in an effort to elucidate any clinical characteristics that are specific to this population.

MATERIALS AND METHODS

Families with >or=2 cases of TGCT enrolled at 18 of the sites participating in the International Testicular Cancer Linkage Consortium were included. We analyzed clinicopathologic characteristics of 985 cases from 461 families.

RESULTS

A majority (88.5%) of families had only 2 cases of TGCT. Men with seminoma (50% of cases) had an older mean age at diagnosis than nonseminoma cases (P = 0.001). Among individuals with a history of cryptorchidism, TGCT was more likely to occur in the ipsilateral testis (kappa = 0.65). Cousin pairs appeared to represent a unique group, with younger age at diagnosis and a higher prevalence of cryptorchidism than other families.

CONCLUSIONS

Clinicopathologic characteristics in these familial TGCT cases were similar to those generally described for nonfamilial cases. However, we observed a unique presentation of familial TGCT among cousin pairs. Additional studies are needed to further explore this observation.

Susceptibility alleles for testicular germ cell tumour: a review

Family history is among the strongest and most consistent of the risk factors for testicular germ cell tumour (TGCT). Brothers of affected cases have an 8- to10-fold relative risk and fathers/sons have a risk between four and sixfold. The familial relative risk of TGCT is higher than for most other cancer types, which rarely exceeds four. The high relative risk suggests that inherited susceptibility to TGCT may account for a substantial fraction of TGCT cases. The search for TGCT susceptibility genes has proven difficult and a recent genome-wide linkage study for TGCT susceptibility loci demonstrated no statistically significant regions of linkage with all LOD scores less than two. Moreover, a previous report of linkage to a region on Xq27 was not replicated. The results from genetic linkage analysis demonstrate that TGCT susceptibility is likely to be due to several genes, each with a modest effect on disease risk. The Y chromosome, which cannot be analysed by genetic linkage, carries a number of testis- and germ cell-specific genes. We recently demonstrated that a deletion on the Y chromosome known as 'gr/gr' is a rare, low-penetrance allele that is associated with susceptibility to TGCT. Based on the evidence from the linkage search the 'gr/gr' deletion represents one of possibly many TGCT susceptibility alleles, and new and emerging technologies will be employed in future work to identify these genes.