Cancer and Exercise
Terri Sullivan DPT, OCS
These days, most people either know of someone or they themselves have been diagnosed with cancer. There have been some previous studies performed that suggested that physical activity could help prevent cancer, but the correlative evidence was rather vague and broad.
However, in a recent JAMA journal article(3), they have more conclusive evidence from a large scale study. It turns out that moderate-to-vigorous physical activity can reduce the incidence of at least 13 cancers by 20%. That includes 3 out of 4 of the most commonly diagnosed cancers worldwide. The study used pooled data from 8 studies in the U.S. and 4 in Europe to look at the relationship between physical activity and 26 different cancers among 1.44 million participants who had no cancer. The individuals were between the ages of 18 to 98 with 57% being women. The type of physical activity that was included was moderate-to-vigorous activity that generated 3-6+ metabolic equivalents (METS). By definition, moderate activity includes brisk walking, heavy cleaning in the house, mowing the lawn, etc; vigorous activity includes jogging, bicycling (fast), lifting heavier weights, basketball. The researchers translated the physical activity rates into percentiles and compared those in the 10th and the 90th. For individuals who were in the 90th percentile for exercise rates, there was a 20% drop in the risk of esophageal, liver, lung, gastric cardia, endothelium, and kidney cancers. There was also a 10-20% reduction in the risk of myeloma, bladder, breast, colon, and rectal cancer. Overall, the higher levels of physical activity translated to a 7% lower risk in total cancer. In addition, individuals with a higher body mass index (BMI) also had a reduction in cancer risk similar to those with a lower BMI. For former smokers who participated in physical activity, there was a reduction in myeloma and lung cancer, but effect on risk for other cancers was not as relevant. In another study regarding digestive system cancers, higher levels of physical activity, up to 10 hours/wk, was associated to decreased risk.2 Similar results were found in a study about leisure activities and pancreatic cancer (with an 11% reduction in risk)1. This information provides just one more reason why even light physical activity can be beneficial to the body as a whole.
1. Farris M, McFadden AA, Friedenreich CM, Brenner DR. Association Between Leisure Time Physical Activity and Pancreatic Cancer Risk in Adults: A Systematic Review and Meta-Analysis. Cancer Epidemiol Biomarkers Prev. 2015 Oct;24(10):1462-73.
2. Keum N, Bao Y, Smith-Warner SA, et al. Association of Physical Activity by Type and Intensity With Digestive System Cancer Risk. JAMA Oncol. Published online May 19, 2016.
3. Moore SC, Lee I, 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;176(6):816-825.
