Physical activity has been shown to lower risk for several diseases such as hypertension and coronary heart disease. Interestingly, having an active lifestyle also lowers risk for 13 cancers, a new study has revealed.
Researchers from the National Cancer Institute (NCI), American Cancer Society (ACS) and National Institutes of Health (NIH) found that individuals who engage in more physical activities have a significantly lower risk of developing cancer than those who lead a sedentary lifestyle.
Past studies have already identified the correlation between physical activity and cancer development, but most of them are inconclusive because of a small sample size. In the present study, the researchers collected and analyzed records of more than 1.44 million individuals with ages ranging from 19 years old to 98 years old from Europe and the U.S.
With this, the researchers were able to study the association of physical activity with a broad range of malignancies, including the rare cancers.
Individuals with leisurely physical activities were found to have a 20 percent lower risk of developing 10 cancers, with the highest risk reduction in liver cancer, kidney cancer, gastric cancer, esophageal adenocarcinoma and myeloid leukemia. Malignancies of the bladder, rectum, head and neck and myeloma were also found to develop less likely, but not as significant as the other cancers previously mentioned.
Previous and current smokers were also found to have significant risk reductions.
"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," said lead author Steven Moore, Ph.D., M.P.H. of the NCI Division of Cancer Epidemiology & Genetics, Metabolic Epidemiology Branch. "Health care professionals counseling inactive adults should promote physical activity as a component of a healthy lifestyle and cancer prevention."
In the study, the median level of leisure-time physical activity was 150 minutes of moderate physical activity weekly. Activities included swimming, running, walking and other moderate to intense physical activities.
Three mechanisms are believed to cause cancer prevention through physical activity, including insulin and insulin-like growth factors, estrogen and androgens, and insulin metabolism and inflammation.
A past study has shown that individuals diagnosed with prostate cancer have better prognostic outcomes when they follow a fitness regimen.
Moreover, cancer growth may also be prevented by other mechanisms such as immune function and oxidative stress reduction. For colon cancers, increased physical activity contributes to lesser transit time of waste in the gut.
"This study linking physical activity has far reaching value for cancer prevention," said co-author Alpa Patel, Ph.D. from the ACS.
The study was published in JAMA Internal Medicine on May 16.