||Mai PL, Friedlander M, Tucker K, Phillips KA, Hogg D, Jewett MA, Lohynska R, Daugaard G, Richard S, Bonaïti-Pellié C, Heidenreich A, Albers P, Bodrogi I, Geczi L, Olah E, Daly PA, Guilford P, Fosså SD, Heimdal K, Liubchenko L, Tjulandin SA, Stoll H, Weber W, Easton DF, Dudakia D, Huddart R, Stratton MR, Einhorn L, Korde L, Nathanson KL, Bishop DT, Rapley EA, Greene MH
||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.