Family history and prostate cancer risk.

The authors examined the relation between family history of prostate cancer and the risk of this cancer in a population-based case-control study conducted in Massachusetts between December 1992 and October 1994. Cases were all incident cases of prostate cancer in men younger than 70 years (n = 563); controls were men with no history of the disease matched to the cases on age and town of residence (n = 703). Prostate cancer risk was increased among men who reported a history of this cancer in either their fathers or brothers (odds ratio (OR) = 2.3, 95% confidence interval (CI) 1.7-3.3). Risk varied with the number of relatives affected and their relationship to the case. For a history of prostate cancer in one relative, the OR was 2.2 (95% CI 1.5-3.2); if two or more relatives were affected, it was 3.9 (95% CI 1.7-5.2). For prostate cancer in the father, the OR was 1.9 (95% CI 1.2-3.0); for prostate cancer in a brother, it was 3.0 (95% CI 1.8-4.9). Risk was inversely related to the subject's age and to age at diagnosis of prostate cancer in his affected relative. Among probands younger than 60 years, the OR was 5.3 (95% CI 2.5-12); for those 60-64 years of age, the OR was 2.7 (95% CI 1.3-5.5); and for those 65 years of age and older, the OR was 1.6 (95% CI 1.0-2.5). For prostate cancer diagnosed in a relative before age 65, the OR was 4.1 (95% CI 2.3-7.3); for detection of the disease after age 74, the OR was 0.76 (95% CI 0.38-1.5). The association was present both among men with local and advanced stage disease and among men whose prostate cancer was detected either by screening or because of symptoms. These data provide evidence that after controlling for diet and other potential confounders, familial factors are significantly associated with the risk of prostate cancer.