Dive Brief:
- A research team with members from the National Cancer Institute and the American Cancer Society analyzed data on 1.44 million people and confirmed that leisure-time physical activity was associated with lower risk of colon, breast, and endometrial cancers in a study published Monday in JAMA Internal Medicine.
- The activity was also associated with lower risk of 10 other cancers, with the greatest risk reductions for esophageal, liver, kidney, gastric cardiac cancers, and myeloid leukemia.
- The study authors said their results showed the physical activity association with reduced cancer risk was "broadly generalizable to different populations," including the obese or smokers.
Dive Insight:
Significant risk reductions among study participants were seen in myeloma, head, neck, rectal, and bladder cancers. Reduced risk for lung cancer was only seen for current and former smokers.
Healthcare providers should encourage inactive adults to exercise, the study authors concluded.
Several examples of leisure-time physical activity include walking, running, swimming, etc. The average level of activity in the study was about 2.5 hours of moderate activity per week.
Various mechanisms may be involved in how physical activity reduces cancer risk. There are three metabolic pathways affected by exercise: insulin and insulin growth factors; proteins involved with insulin metabolism and inflammation; and sex steroids - estrogens and androgens.
Additional mechanisms thought to be associated with exercise and cancer risk include immune function, oxidative stress, and inflammation.
The association between physical activity and reduced cancer risk was not changed due to body mass index and was similar in those of normal weight and overweight groups as well as smokers and non-smokers.
By establishing a link between exercise and 10 additional cancers the study shows it has "far-reaching value for cancer prevention," study co-author Dr. Alpa V. Patel from the American Cancer Society said in a prepared statement.
An estimated 1.68 million Americans will be newly diagnosed with cancer this year and an estimated 595,690 cancer deaths, according to the American Cancer Society.