Objective: To identify published studies quantifying familial prostate cancer risks in relatives of prostate cancer cases and, by meta-analysis, obtain more precise estimates of familial risk according to the family history.
Methods: Thirteen case-control and cohort studies were identified which have reported risks of prostate cancer in relatives of prostate cancer cases. Pooled estimates of risk for various categories of family history were obtained by calculating the weighted average of the log relative risk (RR) estimates from studies.
Results: The pooled RR (95% confidence interval) in first-degree relatives was 2.5 (2.2-2.8). There was evidence that this was highest in relatives of cases diagnosed before age 60 years and that RRs declined with age. The risk for the few men with two affected relatives was increased 3.5-fold (2.6-4.8). RRs to sons of cases appeared to be lower than in brothers; a complete explanation of this observation is uncertain.
Conclusion: Men with a family history of prostate cancer have a significantly greater risk of developing prostate cancer than those with no such history. Risks are greatest for relatives of cases diagnosed when young and those with more than one relative affected.