Here’s one more reason to take a break and exercise: A recent study links leisure-time physical activities with a lower risk of developing 13 different types of cancer. The international team of investigators pooled data from 12 prospective U.S. and European cohorts with self-reported physical activity that included more than 1.4 million participants and 186,932 cases of cancer. The greatest risk reductions were for esophageal adenocarcinoma, liver cancer, cancer of the gastric cardia, kidney cancer, and myeloid leukemia. Previous research has examined the links between physical activity and cancer risk and shown reduced risks for colon, breast, and endometrial cancers, but these studies have been underpowered to make the connection with other forms of cancer.
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“Leisure-time physical activity is known to reduce risks of heart disease and risk of death from all causes, and our study demonstrates that it is also associated with lower risks of many types of cancer,” said Steven C. Moore, PhD, MPH, an investigator at the National Cancer Institute. “Furthermore, our results support that these associations are broadly generalizable to different populations, including people who are overweight or obese, or those with a history of smoking. Health care professionals counseling inactive adults should promote physical activity as a component of a healthy lifestyle and cancer prevention.”
For 13 cancers, increased levels of leisure-time physical activity were associated with lower risk: esophageal adenocarcinoma (hazard ratio [HR] 0.58, 95%; confidence interval [CI] 0.37-0.89); liver (HR 0.73, 95% CI 0.55-0.98); lung (HR 0.74, 95% CI 0.71-0.77); kidney (HR 0.77, 95% CI 0.70-0.85); gastric cardia (HR 0.78, 95% CI 0.64-0.95); endometrial (HR 0.79, 95% CI 0.68-0.92); myeloid leukemia (HR 0.80, 95% CI 0.70-0.92); myeloma (HR 0.83, 95% CI 0.72-0.95); colon (HR 0.84, 95% CI 0.77-0.91); head and neck (HR 0.85, 95% CI 0.78-0.93); rectal (HR 0.87, 95% CI 0.80-0.95); bladder (HR 0.87, 95% CI 0.82-0.92); and breast (HR 0.90, 95% CI 0.87-0.93). Conversely, leisure-time physical activity increased the risks of malignant melanoma (HR 1.27, 95% CI 1.16-1.40) and prostate cancer (HR 1.05, 95% CI 1.03-1.08).
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According to the authors, the associations were similar between patients who were overweight/obese and those who were normal weight. They also noted that smoking status modified the association with lung cancer but not other smoking-related cancers.
The amount of exercise was important for some of the cancers. The risk of developing 7 of the cancer types was at least 20% lower for the most active participants (90th percentile of activity) compared with the least active participants (10th percentile of activity).
A number of physical activity mechanisms can affect cancer risk. It has been hypothesized that cancer growth could be initiated or abetted by 3 metabolic pathways that also are affected by exercise: sex steroids (estrogens and androgens); insulin and insulin-like growth factors; and proteins involved with both insulin metabolism and inflammation. Additionally, several non-hormonal mechanisms have been hypothesized to link physical activity to cancer risk, including inflammation, immune function, oxidative stress, and, for colon cancer, a reduction in time that it takes for waste to pass through the gastrointestinal tract.
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“For years, we’ve had substantial evidence supporting a role for physical activity in three leading cancers: colon, breast, and endometrial cancers, which together account for nearly one in four cancers in the United States,” said another study author, Alpa V. Patel, PhD, a cancer epidemiologist at the American Cancer Society. “This study linking physical activity to 10 additional cancers shows its impact may be even more relevant, and that physical activity has far reaching value for cancer prevention.”
Increased physical activity associated with lower risk of 13 types of cancer [press release]. Bethesda, MD: National Institutes of Health; May 16, 2016.