Cancer incidence due to excess body weight and leisure-time physical inactivity in Canada: implications for prevention.

OBJECTIVE

This analysis aimed to estimate the number of incident cases of various cancers attributable to excess body weight (overweight, obesity) and leisure-time physical inactivity annually in Canada.

METHODS

The number of attributable cancers was estimated using the population attributable fraction (PAF), risk estimates from recent meta-analyses and population exposure prevalence estimates obtained from the Canadian Community Health Survey (2000). Age-sex-site-specific cancer incidence was obtained from Statistics Canada tables for the most up-to-date year with full national data, 2007. Where the evidence for association has been deemed sufficient, we estimated the number of incident cases of the following cancers attributable to obesity: colon, breast, endometrium, esophagus (adenocarcinomas), gallbladder, pancreas and kidney; and to physical inactivity: colon, breast, endometrium, prostate, lung and/or bronchus, and ovarian.

RESULTS

Overall, estimates of all cancer incidence in 2007 suggest that at least 3.5% (n=5771) and 7.9% (n=12,885) are attributed to excess body weight and physical inactivity respectively. For both risk factors the burden of disease was greater among women than among men.

CONCLUSION

Thousands of incident cases of cancer could be prevented annually in Canada as good evidence exists for effective interventions to reduce these risk factors in the population.