By: H.C. George Wong, MD, FRCPC
Cardiac adverse complication/prevention and cancer risk in the risk-benefit paradox of exercise
Issue: BCMJ,
vol. 58, No. 6, July August 2016,
Pages 302,304 Letters
The article by Warburton and colleagues [BCMJ 2016;58:210-218] reports on the risk-benefit paradox of exercise. There is a transient increase in short-term risk for an adverse cardiac event with vigorous exercise and a reduction in long-term risk for chronic disease and premature mortality with relatively small amounts of exercise.
The recently published pooled analysis by Moore and colleagues[1] on leisure-time physical activity in the risk of cancer development provides a different paradox. Leisure-time physical activity is found to be associated with lower risks of approximately half (13) of the cancer types regardless of BMI or smoking status. They include esophageal adenocarcinoma, liver, lung, kidney, gastric cardia, endometrial, myeloid leukaemia (20% or more lower risk), and others. In contrast, there is an increased risk in prostate cancer (5% higher risk) and melanoma (up to 27% higher risk), although the former may be related to screening bias and the latter to UV exposure.
The invited commentary on the Moore article by McCullough and colleagues[2] suggests further research is needed to assess the critical timing of physical activity needed for optimal cancer risk reduction. Clarification is also needed on the types and amount of leisure-time activity (e.g., running, cycling, or walking).
There is a risk-benefit paradox of exercise in cardiac adverse complication/prevention and cancer risk.
—H.C. George Wong, MD
Vancouver
References
1. Moore SC, Lee IM, Weiderpass E, et al. Association of leisure-time physical activity with risk of 26 types of cancer in 1.44 million adults. JAMA Intern Med 2016;doi:10.1001/jamainternmed.2016.1548 [e-pub ahead of print].
2. McCullough LE, McClain KM, Gammon MD. The promise of leisure-time physical activity to reduce risk of cancer development. JAMA Intern Med 2016;176:826-827.
