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Vigorous Physical Activity and Risk of Prostate Cancer

Objective: To examine the incidence and progression of prostate cancer in middle-aged and elderly male health professionals. Design: Cohort study (Health Professionals Follow-up Study). Setting: The cohort was drawn from registries of US dentists, optometrists, osteopaths, podiatrists, pharmacists, and veterinarians in 1986 and was followed until January 31, 2000. Participants: The 1986 mailed questionnaire was returned by 51,529 men aged 40 to 75 years (mean age B54 y). Men who did not have diagnosed cancer at baseline and who adequately completed a dietary and physical activity questionnaire were included in the follow-up study (n=47,620). Assessment of risk factors: The baseline questionnaire included information on demographics, height and weight, ancestry, medical history, and lifestyle characteristics, including physical activity and diet. Physical activity and other information were updated on biennial mailed questionnaires. The respondents reported the average time per week that they spent walking, running, bicycling, playing racquet sports, and other aerobic activities, and after 1990, weight training. The physical activity score was generated from activity-specific metabolic equivalent (MET) hours per week, and divided into quintiles. Men who did no vigorous recreational physical activity (ie, they reported only walking and stair climbing) were compared with 4 quartiles of vigorous physical activity. Main outcome measures: The main outcome measures were incidence of prostate adenocarcinoma, Gleason histologic grade, and fatalities from prostate cancer in relation to level of physical activity. Participants reported new diagnoses which were then verified from medical records and pathology reports in B90% of 3006 cases diagnosed during 596,796 person-years. T1a cancers were excluded. Data on deaths were obtained from family reports, the National Death Index, and the US Postal Service, and details were verified from records. Follow-up was 96%. Main results: Total physical activity (from the most recent physical activity assessment) was not clearly associated with incidence of prostate cancer [multivariable-adjusted relative risk (RR), 1.02; 95% confidence interval (CI), 0.91–1.15; P for trend, 0.47] in a comparison of the least and most active quintiles of physical activity. Nor was total or nonvigorous physical activity associated with nonadvanced, advanced, or fatal prostate cancer. In age-adjusted analysis, no association was observed between vigorous physical activity and total prostate cancer (RR, 1.09; CI, 0.97–1.23; P for trend, 0.05) but vigorous activity was positively associated with nonadvanced prostate cancer (1.21; CI, 1.07–1.37; P for trend, 0.002). Because of heterogeneity by age, the sample was stratified by age <65 years and Z65 years. Among men Z65 years, risk was lower for both advanced prostate cancer and for fatal cancer in the highest category of vigorous physical activity (>29METh/wk) compared with no vigorous activity (RR, 0.33; CI, 0.17–0.62 and RR, 0.26; CI, 0.11–0.66, respectively), but no association was found for younger men. Changes in physical activity during follow-up and frequency of PSA examination did not seem to influence the results. For 2159 cases with data on the Gleason grade, men in the highest category of vigorous physical activity were less likely to be diagnosed with poorly differentiated cancers (Gleason grade Z7) than men in the lowest category (odds ratio, 0.64; CI, 0.47–0.87). Conclusion: For men Z65 years, incidence of advanced and fatal prostate cancer was reduced among those who were most vigorously physically active. For younger men, and for total incidence, no associations were found.