Lifetime physical activity and cancer incidence—A cohort study of male former elite athletes in Finland

Abstract

Physical activity has been shown to decrease the risk of certain cancers. Objective of this study was to assess the effect of physical activity on cancer incidence in former male athletes in older age. A cohort of 2448 elite male athletes and 1712 referents was followed-up for cancer incidence during 1986-2010 through the Finnish Cancer Registry. Standardised incidence ratios were calculated with the general male population as the reference. Self-reported questionnaire-based data on covariates were used in Cox regression analyses comparing the risk of cancer in athletes and referents. The overall cancer incidence was lower in athletes than in the general population, standardised incidence ratio 0.89 (95% confidence interval 0.81-0.97). It was lowest among middle-distance runners (standardised incidence ratio 0.51, 95% confidence interval 0.22-1.01), long-distance runners (standardised incidence ratio 0.57, 95% confidence interval 0.35-0.88) and jumpers (standardised incidence ratio 0.60, 95% confidence interval 0.37-0.92). The standardised incidence ratio of lung cancer among athletes was 0.40 (95% confidence interval 0.27-0.55) and that of kidney cancer 0.23 (95% confidence interval 0.06-0.57). The hazard ratio for lung cancer between athletes and referents increased from the unadjusted ratio of 0.29 (95% confidence interval: 0.18-0.48) to 0.61 (95% confidence interval: 0.30-1.26) after adjustment for smoking status and pack-years of smoking. Former male elite athletes evidently have less cancer than men on the average. The lesser risk can be attributed to lifestyle factors, notably less frequent smoking among the athletes.