Objectives: To examine the associations of physical activity and body size with risk of prostate cancer.
Methods: At baseline in 1988, 8922 men (mean age 67 years) completed a health questionnaire which included information on physical activity, body weight, and waist girth. In a subgroup (74% of men), physical activity data also had been provided in 1962 or 1966 and again in 1977. Additionally, body weight measured at age 18 was available for 92% of men. During follow-up from 1988 through 1993, 439 men developed prostate cancer.
Results: In multivariate analyses that accounted for potential confounders, the RRs (95% CI) for < 4200, 4200-8399, 8400-12,599, and > or = 12,600 kJ/week of physical activity at baseline were 1.00 (referent), 1.13 (0.84-1.52), 0.96 (0.68-1.35), and 1.04 (0.79-1.38), respectively. For body mass indexes (BMI) of < 22.5, 22.5-24.9, 25.0-27.4, and > or = 27.5 kg/m2 at baseline, corresponding results were 1.00 (referent), 1.27 (0.94-1.71), 1.26 (0.92-1.72), and 1.02 (0.68-1.53), respectively. For waist girths of < or = 86.4, 86.5-91.4, 91.5-96.5, and > 96.5 cm, they were 1.00 (referent), 1.30 (0.96-1.76), 1.31 (0.96-1.80), and 1.19 (0.85-1.65), respectively. Combining physical activity measures from the past, or examining vigorous activities only, did not yield any significant associations. BMI at age 18 also was not related to risk.
Conclusion: These findings do not support a role of physical activity or body weight in prostate cancer etiology.