| Testicular germ cell tumors (TGCT) are the most commonly diagnosed neoplasm of young men 15-45 years of age, and incidence of these tumors has been increasing in recent decades for reasons currently unknown. Histologic type of TGCT can be divided into the broad categories of seminomas and non-seminomas. It currently remains to be elucidated if these histologic types share a common etiology. In this study we analyzed the largest set of bilateral cases of TGCT ever assembled, 550, to determine if the histologic type of the first tumor predicts that of the second. Presuming an individual with a history of two primary tumors has the same risk factors for both tumors, a concordance of histologic types in the same individual would suggest that the risk factors for seminomas and non-seminomas differ. The data show no association between the histologic type of the first and second tumors when the analysis is adjusted for the age at first diagnosis (odds ratio (OR)=0.95) This finding suggests that the two broad histologic types share a common etiology, but some age related factor impacts differentiation between the two. We also compared 16,204 presumed unilateral cases of TGCT to 440 bilateral cases matched on year of birth and region of diagnosis to determine if histologic type of the first/only TGCT confers risk of developing a second TCGT. This analysis suggests that a first diagnosis of seminoma is a risk factor for developing testicular cancer after adjustment for age at first or only diagnosis (OR=1.401; 95% CI=1.135-1.730). This finding suggests that seminomatous first tumors should be considered as a risk factor for the development of bilateral TCGT despite the current view that non-seminomatous TGCT are considered to be more aggressive. |
