Recreational physical activity and prostate cancer risk (United States).Cancer Causes Control 2006; 17(6):831-41CC
To examine recreational physical activity (PA) and prostate cancer risk in a large cohort of men living in Washington State, focusing on frequency and type of physical activity at various times throughout life.
In a prospective cohort study, we assessed physical activity in 34,757 men (50-76 years at baseline) using a questionnaire. Men were recruited into the study between 2000 and 2002. Five hundred and eighty-three men developed prostate cancer.
Using Cox proportional hazards regression, PA either in the 10 years before baseline or earlier in life was not associated with prostate cancer risk. However, compared to no activity, >or=10.5 MET-h per week (the median level) of PA was associated with a reduced prostate cancer risk among men who were normal weight (HR = 0.69, 95% CI 0.46-1.0), >or=65 years at diagnosis (HR = 0.75, 95% CI 0.55-1.0) and who had not had a recent PSA (HR = 0.47, 95% CI 0.28-0.81). Greater PA was associated with an increased risk among men who were obese (HR = 1.5, 95% CI 0.95-2.4), and no association among men <65 years or with a recent history of PSA screening (all p for interactions <or=0.02).
PA was not associated with prostate cancer risk, except in subgroups defined by age, obesity, and screening history.