A new study has found that high levels of physical activity can help lower risks of developing 13 types of cancer. The findings were published online in the journal JAMA Internal Medicine, on May 16.
The overall finding of the study was that people who reported spending a decent amount of their time exercising reduced their risk of developing seven kinds of cancer by at least 20 percent.
However, the study could not find a cause-and-effect relationship, proving, only, an association between exercise and reduced cancer risk.
The research
Steven C. Moore, Ph.D., M.P.H., of the National Cancer Institute, Bethesda, Md., and coauthors created a database of 1.4 million adults, based on data from 12 United States and European cohorts. The study used people who reported any type of physical activity.
The adult’s age range was 19 to 98, and the researchers analyzed associations between their physical activity and incidence of 26 kinds of cancer.
People who walked over an hour a day were considered big exercisers. But on average, people investigated did two and a half hour of walking every week.
The results showed that exercise helped reduce the risk of developing half of the types of cancers considered in the investigation. Also, researchers found that the higher levels of physical activity led to a 7 percent of lower risks of cancer, in total.
People who exercised the most had a 42 percent lower risk of esophageal cancer, 10 percent lower risk of breast cancer, 13 percent lower risk of rectal and bladder cancer, 23 percent lower risk of kidney cancer, 22 percent lower risk of stomach cancer, 21 percent lower risk of endometrial cancer, 15 percent lower risk of head and neck cancer, 16 percent lower risk of colon cancer, 20 percent lower risk of myeloid leukemia and 17 percent lower risk of myeloma.
Benefits of physical activity
The study found that the levels of hormones are reduced due the physical activity. The hormones, such as estrogen, are linked to different types of cancer. Physical activity can help control levels of insulin and insulin-like growth factor.
“This suggests that physical activity may have a role to play in population-wide cancer prevention efforts,” Moore said.
Moore also added that the results of the study can be generalized to different populations, as well as people who are overweight or obese, or those with a history of smoking.
The team of researchers explained that doctors should prescribe exercise to their patients, because, for example, only half of Americans exercise as recommended.
Other findings
However, it was also found that physical activity was associated with a 5 percent higher risk of prostate cancer and a 27 percent higher risk of malignant melanoma.
The higher risk of melanoma may be due to the fact that people often exercise outside and without sunscreen. This is why doctors need to ask their patients to use sunscreen while going outside.
Source: JAMA Internal Medicine