Fatherhood status in relation to prostate cancer risks in two large U.S.‐based prospective cohort studies

BACKGROUND: Despite the high incidence and mortality of prostate cancer (PCa) in the Unites States, few risk factors have been consistently linked with these PCa outcomes. Assessing proxies of reproductive factors may offer insights into PCa pathogenesis. In this study, we examined fatherhood status as a proxy of fertility in relation to total, nonaggressive, aggressive, and fatal PCa. METHODS: We examined participants of two cohorts, the NIH‐AARP Diet and Health (NIH‐AARP) Study and Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals of associations between fatherhood status and number of children sired in relation to PCa incidence. RESULTS: Fatherhood status (one or more children vs. childless) was positively associated with total PCa risk in NIH‐AARP or PLCO, but was not statistically significant (p = 0.06 and 0.55, respectively). Number of children sired indicated a slightly elevated risk of total PCa, but HRs were rarely significant and were of a fairly constant magnitude with no discernable trend relative to the childless referent group. Associations were similar for nonaggressive and aggressive PCa. The trend test for fatal PCa was statistically significant in NIH‐AARP (p (trend) < 0.01), despite none of the individual categorical point estimates reaching this threshold. CONCLUSION: This study provides tentative evidence that fathering children is associated with a slightly increased PCa risk. Future research should strive to assess better proxies of reproductive function in relation to aggressive and fatal PCa to provide more specific evidence for this putative relationship.