While we often focus on cardiovascular risk benefits associated with exercise, it can reduce your risk of getting cancer, too.
I have often extolled physical activity virtues, whether through walking or running, weight lifting, or yoga. We often think of physical activity in terms of its impact on chronic diseases such as cardiovascular disease and diabetes. As a cancer doctor and as a proponent of physical movement (of any type), I would like to chat about the cancer risk-reducing properties of exercise. We will look at the effect of exercise on various cancers.
Scope of the Problem
In the USA, 1.7 million individuals are diagnosed with invasive cancer each year, and more than six hundred thousand will die of the disease. We have to do better, and one strategy is risk reduction. However, our understanding of the relation between physical activity and cancer risk, and whether commonly recommended amounts of physical activity (for example, 2.5 to 5 hours per week of moderate-intensity exercise or 7.5 to 15 metabolic equivalent task [MET] hours per week) is adequate to reduce your risk of getting cancer. Some studies have not linked engagement in the recommended amounts of physical activity and significantly lower cancer risk.
Meta-analysis analyzes data from several studies. We have a recent large meta-analysis of nine prospective cohorts involving more than seven hundred and fifty thousand individuals.
Individuals who performed moderate-intensity activity for 2.5 to five hours per week had a significantly lower risk of several cancers:
- breast cancer
- colon cancer (men only)
- uterus (endometrial) cancer
- kidney cancer
- liver cancer
- non-Hodgkin lymphoma (women only)
Amount of risk reduction
The strength of the associations between the recommended amounts of physical activity and no activity ranged from a six to ten percent lower risk for breast cancer, to an eighteen to twenty-seven percent drop in the chances of developing liver cancer.
Researchers from the Division of Cancer Epidemiology and Genetics, National Cancer Institute (USA) published these exciting findings in the 26 December 2019 issue of the Journal of Clinical Oncology. Charles Matthews, Ph.D., and colleagues note that this is an observational study and cannot establish causality; for example, maybe healthier folks exercise. It could be their general good health that leads to a lower risk of getting cancer. That said, the study authors observe that these results offer the best description of the dose-response for physical activity and cancer risk.
We have older studies that established the cancer risk-reducing properties of physical activity for cancers of the dose-response breast. In 2018 the Physical Activity Guidelines Advisory Committee noted that there is “strong evidence that activity is linked with a drop in the risk of getting several cancers,” including uterus and bladder cancer, esophageal adenocarcinoma, kidney cancer, and stomach cancer.
Exercise: How Much?
Researchers attempted to determine what effect the recommended amount/intensity of exercise had on cancer risk. They discovered that those who achieved the recommended amounts of activity (7.5 to 15 MET- hours/week) appeared associated with a lower risk of seven of the fifteen cancer types included in the study.
- breast cancer: 6 to 10 percent lower risk
- colon cancer (men only): 8–14 percent lower risk in men
- uterus cancer: 10 to 18 percent lower risk
- kidney cancer: 11 to 17 percent lower risk
- liver cancer: 18 to 27 percent lower risk
- myeloma: 14 to 19 percent lower risk
- lymphoma (non-Hodgkin): 11 to 18 percent lower risk
Of note, the researchers did not examine lung cancer because of probable confounding by smoking.
The investigators went further, evaluating adjusted associations separately for moderate- and vigorous-intensity physical activity for the nine cancers that appeared to be significantly associated with exercise. The bottom line? Moderate-intensity activity has a most pronounced effect on breast and kidney cancer, whereas uterus cancer risk dropped with vigorous activity. Colon cancer had a borderline significance for both moderate-intensity and vigorous exercise.
Health care providers and those who care about wellness should encourage able adults to maintain physical activity at recommended levels to lower risks of multiple cancers. We can reduce our risk of getting cancer via lifestyle! Health care providers and others who care about wellness should encourage adults to perform physical activity to drop their cancer risk.
Most of our cancer risk is not related to how much (or how little) physical activity you and I get, but we have one more tool in the toolbox.
I’m Dr. Michael Hunter. Thank you for joining me today.
- Office of Disease Prevention and Health Promotion: 2018 Physical Activity Guidelines Advisory Committee: Physical Activity Guidelines Advisory committee Scientific Report. Washington, DC, US Department of Health and Human Services, 2018.
- Patel AV, Friendenreich CM, Moore SC, and others. American College of Sports Medicine roundtable report on physical activity, sedentary behavior, and cancer prevention and control. Med Sci Sports Exerc 51:2391–2402, 2019.