Physical Activity from Early Adulthood and Risk of Prostate Cancer: A 24-Year Follow-Up Study among Icelandic Men

Abstract

Physical activity in adult life may reduce prostate cancer risk. Data are scarce on the role of activity during early adulthood, as well as combined recreational and occupational physical activity on prostate cancer risk and mortality. We undertook a prospective study of 8,221 Icelandic men (born 1907 to 1935) in the population-based Reykjavik Study. At enrollment, between 1967 and 1987, the men provided information on regular recreational physical activity since the age of 20 years as well as current occupational activity. Through linkage to nationwide cancer and mortality registers, the men were followed for prostate cancer diagnosis and mortality through 2009. We used Cox models to calculate the relative risk of prostate cancer by level of physical activity. During a mean follow-up of 24.8 years, 1,052 men were diagnosed with prostate cancer, of whom 349 had advanced disease (stage 3+ or prostate cancer death). Neither recreational nor occupational physical activity was, independently or combined, associated with overall or localized prostate cancer. Compared with physically inactive men, we observed a nonsignificant lower risk of advanced prostate cancer [HR, 0.67; 95% confidence interval (CI), 0.42-1.07] among men reporting both recreational and occupational physical activities (P value for interaction = 0.03). Awaiting confirmation in larger studies with detailed assessment of physical activity, our data suggest that extensive physical activity beginning in early adulthood may reduce the risk of advanced prostate cancer.