Abstract
OBJECTIVES: It was previously estimated that 1814 (1.6 % of incident cancers) were attributable to physical inactivity in Australia in 2010, when only three sites were considered. We estimated the burden of cancer due to physical inactivity in Australia for 13 sites. DESIGN: The population attributable fraction estimated site-specific cancer cases attributable to physical inactivity for 13 cancers. The potential impact fraction was used to estimate cancers that could have been prevented in 2015 if Australian adults had increased their physical activity by a modest amount in 2004-05. METHODS: We used 2004-05 national physical activity prevalence data, 2015 national cancer incidence data, and contemporary relative-risk estimates for physical inactivity and cancer. We assumed a 10-year latency period. RESULTS: An estimated 6361 of the cancers observed in 2015 were attributable to physical inactivity, representing 4.8 % of all cancers diagnosed. If Australian adults had increased their physical activity by one category in 2004-05, 2564 cases (1.9 % of all cancers) could have been prevented in 2015. CONCLUSIONS: More than three times as many cancers are attributable to physical inactivity than previously reported. Physical activity promotion should be a central component of cancer prevention programmes in Australia.