State of the epidemiological evidence on physical activity and cancer prevention

European Journal of Cancer
Volume 46, Issue 14 , Pages 2593-2604, September 2010
* Christine M. Friedenreich
o Department of Population Health Research, Alberta Health Services, 1331 29 St NW, Calgary, Alberta, Canada T2N 4N2
o Departments of Oncology and Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
o Corresponding Author InformationCorresponding author at: Department of Population Health Research, Alberta Health Services, 1331 29 St NW, Calgary, Alberta, Canada T2N 4N2. Tel.: +1 403 521 3841; fax: +1 403 270 8003.
* , Heather K. Neilson
o Department of Population Health Research, Alberta Health Services, 1331 29 St NW, Calgary, Alberta, Canada T2N 4N2
* , Brigid M. Lynch
o Department of Population Health Research, Alberta Health Services, 1331 29 St NW, Calgary, Alberta, Canada T2N 4N2
Received 11 March 2010; received in revised form 14 May 2010; accepted 15 July 2010.
Background

Physical activity is a modifiable lifestyle risk factor that has the potential to reduce the risk of most major cancer sites.
Methods

We examined the strength, consistency, dose–response and biological plausibility of an association between physical activity and risk of colon, breast, endometrium, lung, prostate, ovarian, gastric, rectal, pancreatic, bladder, testicular, kidney and haematological cancers. We also estimated the population-attributable risk (PAR) for physical inactivity and cancer in 15 European countries.
Results

There is convincing or probable evidence for a beneficial effect of physical activity on the risk of colon, breast and endometrial cancers. The evidence is weaker for ovarian, lung and prostate cancers and generally either null or insufficient for all remaining cancers. Several hypothesised biological mechanisms include a likely effect of physical activity on insulin resistance, body composition, sex steroid hormones and a possible effect on vitamin D, adipokines, inflammation and immune function. Somewhere between 165,000 and 330,000 cases of the six major cancers (breast, colon, lung, prostate, endometrium and ovarian) could have been prevented in 2008 in Europe alone if the population had maintained sufficient levels of physical activity.
Conclusion

There is strong and consistent evidence that physical activity reduces the risk of several of the major cancer sites, and that between 9% and 19% of cancer cases could be attributed to lack of sufficient physical activity in Europe. Public health recommendations for physical activity and cancer prevention generally suggest 30–60min of moderate or vigorous-intensity activity done at least 5d per week.