Population based incidence and age distribution of spermatocytic seminoma

Purpose: Spermatocytic seminoma is a rare subtype of testicular germ cell tumor which has been reported to occur in elderly men. We report the first population based estimate of incidence, temporal trends and age distribution of this tumor. Materials and Methods: All cases of primary testicular cancer identified by cancer registries in Australia between 1982 and 2002 were available for analysis. The International Classification of Diseases for Oncology code M-9063/3 was used to identify spermatocytic seminomas. Incidence trends were modeled using Poisson regression. Results: There were 58 cases of spermatocytic seminoma out of 9,658 cases of primary malignant testicular neoplasms identified by the cancer registries. This tumor comprised 1.1% of all seminoma and the age standardized incidence rate was 0.4 per million (95% CI 0.3-0.6). A temporal increase in incidence was found but not one reaching statistically significance. Age at diagnosis ranged from 19 to 92 years with a mean of 53.5 (SD 16.7) and a median of 54 years. Conclusions: Spermatocytic seminoma should be considered in the differential diagnosis for testicular germ cell tumors presenting in young adults because this tumor occurs as often in men younger than 55 years as it does in older men. Although rare, the occurrence of this tumor is not as singular as the current literature suggests.