Changes in epidemiologic features of testicular germ cell cancer: Age at diagnosis and relative frequency of seminoma are constantly and significantly increasing

Abstract

ObjectivesTesticular germ cell tumors (GCTs) have their incidence peak in the third and fourth decades of life. Histologically, GCTs comprise of seminoma and nonseminoma at almost equal proportions with a slight preponderance of nonseminoma in most of the major series. Since decades, there is a shift toward decreasing age at presentation. Recently, there are suggestions of a reversal of the age trend, and also, the histologic subtype ratio appears to shift toward seminoma. We retrospectively looked to our patient populations to verify these recent trends. MethodsA total of 2,482 patients with histologically proven GCT diagnosed between 1976 and 2010 were retrospectively evaluated regarding the year of diagnosis, histology of primary tumor, and age at presentation. Patients were categorized according to the following time periods of treatment: before 1990, 1990 to 1994, 1995 to 1999, 2000 to 2004, and 2005 to 2010. Mean age and relative proportion of seminoma were compared among patient categories by employing the chi-square test and analysis of variance, respectively. ResultsThe mean age significantly increased from 28 to 36 years. The age difference between the 2 histologic subtypes remained constant between 6 and 8 years during the entire observation period. The relative proportion of seminoma continuously increased from 30.9% to 56% (P <0.001). ConclusionThere is evidence of a significant shift toward older age at diagnosis of GCT. In addition, the proportion of seminoma is constantly increasing at the expense of nonseminoma. The reasons for these developments are obscure. However, 2 old theories regarding the pathogenesis of GCT may receive support from our results: first, the theory of divergent pathogenetic pathways of seminoma and nonseminoma and second, the involvement of postnatal environmental factors in the pathogenesis of GCTs.