To examine the relation between fatal prostate cancer and family histo
ry of prostate cancer in a first-degree relative, we analyzed data fro
m a prospective mortality study of 481,011 men with no history of canc
er at enrollment in 1982. During 9 years of follow-up, 1,922 deaths fr
om prostate cancer occurred. Results from Cox proportional hazard mode
ls showed that family history of prostate cancer was related to fatal
prostate cancer [rate ratio (RR) = 1.60; 95% confidence interval (CI)
= 1.31-1.97]; men with two or more affected relatives had a greater th
an threefold increase in risk (RR = 3.19; 95% CI = 1.51-6.71). Men who
se relatives were diagnosed with prostate cancer before age 65 years (
RR = 2.03; 95% CI = 1.33-3.09) had a greater effect of family history
than men whose relatives were diagnosed at older ages (RR = 1.50; 95%
CI = 1.17-1.91). Rate ratios did not increase: with decreasing age of
the study participants. The 60% increase in risk for men with at least
one affected relative is lower than that reported in previous studies
.