Abstract
OBJECTIVES: To estimate the proportion and numbers of cancers occurring in Australia in 2010 attributable to insufficient levels of physical activity. METHODS: We estimated the population attributable fraction (PAF) of cancers causally associated with insufficient physical activity (colon, post-menopausal breast and endometrium) using standard formulae incorporating prevalence of insufficient physical activity (<60 minutes at least 5 days/week), relative risks associated with physical activity and cancer incidence. We also estimated the proportion change in cancer incidence (potential impact fraction [PIF]) that may have occurred assuming that everyone with insufficient activity levels increased their exercise by 30 minutes/week. RESULTS: An estimated 1,814 cases of colon, post-menopausal breast and endometrial cancer were attributable to insufficient levels of physical activity: 707 (6.5%) colon; 971 (7.8%) post-menopausal breast; and 136 (6.0%) endometrial cancers. If those exercising below the recommended level had increased their activity level by 30 minutes/week, we estimate 314 fewer cancers (17% of those attributable to insufficient physical activity) would have occurred in 2010. CONCLUSIONS: More than 1,500 cancers were attributable to insufficient levels of physical activity in the Australian population. IMPLICATIONS: Increasing the proportion of Australians who exercise could reduce the incidence of several common cancers.