The risk of testicular cancer is thought to be higher among men seeking infertility treatment compared with the general population. Confirmation of this risk in a large US cohort of at-risk patients is lacking. This study explored the association between male infertility and subsequent development of testicular cancer in a US-based cohort. A total of 51 461 couples evaluated for infertility from 1967 to 1998 were recruited from 15 California infertility centers. We linked data on 22 562 identified male partners to the California Cancer Registry. The incidence of testicular cancer in this cohort was compared with the incidence in an age-matched sample of men from the general population using the Surveillance Epidemiology and End Results program. We analyzed the risk for testicular cancer in men with and without male factor infertility using a Cox proportional hazards regression model. Thirty-four post-infertility-diagnosis cases of histologically confirmed testicular cancer were identified. Men seeking infertility treatment had an increased risk of subsequently developing testicular cancer (standardized incidence ratio, 1.3; 95% confidence interval, 0.9-1.9), with a markedly higher risk among those with known male factor infertility (2.8; 1.5-4.8). In multivariable analysis, men with male factor infertility were nearly 3 times more likely to develop testicular cancer compared with those without (hazard ratio, 2.8; 95% confidence interval, 1.3-6.0). Men with male factor infertility have an increased risk of subsequently developing testicular cancer, suggesting the existence of common etiologic factors for infertility and testicular cancer.
