Anthropometrics and prostate cancer risk.

Studies on obesity and prostate cancer risk are inconsistent, perhaps because of differential effects on aggressive and nonaggressive cancers. Participants included 34,754 men residing in Washington State (aged 50-76 years at baseline) in a prospective cohort study who were recruited between 2000 and 2002; 383 developed aggressive (regional/distant stage or Gleason sum 7-10) and 437 developed nonaggressive disease through December 2004. Compared with normal-weight men (body mass index (kg/m(2)) <25), obese men (> or = 30 kg/m(2)) had a reduced risk of nonaggressive disease (hazard ratio = 0.69, 95% confidence interval: 0.52, 0.93; p for trend = 0.01). Overweight men (25-29.9 kg/m(2)) had an increased risk of aggressive disease (hazard ratio = 1.4, 95% confidence interval: 1.1, 1.8), but there was no increased risk for obese men (p for trend = 0.69). Body mass index of >25 at age 18 years was associated with increased risk of aggressive prostate cancer; obesity at ages 30 and 45, but not 18, years was associated with reduced risk of nonaggressive prostate cancer. Height (fourth vs. first quartile) was associated with an increased risk of total prostate cancer (hazard ratio = 1.3, 95% confidence interval: 1.1, 1.6), which did not differ by aggressiveness. There were no associations of prostate cancer with age at which maximum height was reached. Results from this study demonstrate the complexity of prostate cancer epidemiology and the importance of examining risk factors by tumor characteristics.