It has been controversial that men carrying
a DNA mismatch repair (MMR) gene mutation (
Lynch syndrome) are at heightened risk of
prostate cancer given that an increased risk is likely to be modest and the prevalence of
prostate cancer is high. We used PubMed to search for "molecular studies" that reported
MMR-deficiency status of
prostate cancer tumors in men with an MMR gene mutation, and "risk studies" that reported
prostate cancer risk for men known or suspected to have an MMR gene mutation relative to that for noncarriers or the general population. Of the six molecular studies, 32 of 44 [73%, 95% confidence intervals (CI), 57%-85%]
prostate cancer tumors in carriers were MMR deficient, which equates to carriers having a 3.67-fold increased risk of
prostate cancer (95% CI, 2.32-6.67). Of the 12 risk studies, we estimated a 2.13-fold increased risk of
prostate cancer (95% CI, 1.45-2.80) for male carriers in clinic-based retrospective cohorts, 2.11 (95% CI, 1.27-2.95) for male carriers with a prior diagnosis of
colorectal cancer, and 2.28 (95% CI, 1.37-3.19) for all men from mutation-carrying families. The combination of evidence from molecular and risk studies in the current literature supports consideration of
prostate cancer as part of
Lynch syndrome.