Physical activity and the prevention of cancer: a review of recent findings

A number of lifestyle characteristics have already been well established as risk factors for cancer; these include tobacco smoking, diet, alcohol consumption and obesity. More recently, attention has been drawn to the potential relationship between physical activity and cancer risk. In 2002, the International Agency for Research on Cancer (IARC) published volume 6 of Handbooks of Cancer Prevention: Weight Control and Physical Activity. The IARC report concluded that regular physical activity reduces the risk of breast and colon cancers, and suggested that physical activity also possibly reduces the risk of endometrial and prostate cancers. Since 2002, seven additional reviews and 38 original reports from cohort studies have been identified. These papers cover cancers of the colon/colorectum, breast, endometrium, pancreas, prostate, lung and ovary. This review updates the evidence on physical activity and cancer risk based on these new findings.

It now appears that the decreased risk of colon cancer associated with physical activity is stronger in men than women, and also that the link between breast cancer and physical activity is stronger in post‐menopausal than pre‐menopausal women. The recent evidence also suggests that risk of cancers of the lung and endometrium, and to a lesser extent prostate, is likely to be decreased by physical activity. Yet, there is little or no suggestion that pancreatic or ovarian cancer risk is modified by physical activity. The biological plausibility of the observed associations between physical activity and cancer are supported by a variety of site‐specific and generic mechanisms which are discussed in this review.