Male infertility and prostate cancer risk: a nested case-control study.

The pathogenesis of prostate cancer is unclear, although experimental evidence implicates androgens as playing an important role. Infertile men frequently suffer from some degree of hypogonadism and may hence be hypothesized to be at lower risk of developing prostate cancer than fertile men. To test this hypothesis, we conducted a case-control study nested within "the Malmö Diet and Cancer Study" cohort in Sweden, inviting 661 prostate cancer cases and 661 age-matched controls to participate. Of the 975 (74%) respondents, we excluded 84 childless men with unknown fertility status. Thus, 891 men were included, providing 445 prostate cancer cases and 446 controls. Of these, 841 (94%) men were biological fathers and 50 (6%) men were infertile. Logistic regression showed that the infertile men were at significantly lower risk of being diagnosed with prostate cancer than the fertile men (odds ratio, 0.45; 95% confidence interval, 0.25-0.83). Conditional and unconditional multivariate models, adjusting for socioeconomic, anthropometric, and health-status-related factors, provided similar estimates. We conclude that enduring male infertility is associated with a reduced prostate cancer risk, thus corroborating the theory that normal testicular function, and hence most probably sufficient steroidogenesis, is an important contributing factor to the later development of this malignancy.