Physical Activity Lowers Cancer Risk

Recommended levels of exercise found to decrease the risk of cancer in 13 of 26 cancer types.

Physical activity helps lower the risk of 12 cancer types, a study published in JAMA Internal Medicine found.

It’s estimated that 51% of Americans and 31% of people globally do not partake in the recommended levels of physical activity.

A study that pooled data from 12 United States and European cohorts with self-reported physical activity between 1987 and 2004 analyzed the association between physical activity and the incidence of 26 cancer types.

There were 1.4 million patients involved in the study and 186,932 cancers identified during a median follow-up of 11 years. The results of the study showed an association between higher physical activity levels and a lower cancer risk in 13 out of 26 cancer types compared with lower physical activity levels.

The 13 lower cancer risk types included: esophageal adenocarcinoma (42%); liver (27%); lung (26%); kidney (23%); gastric cardia (22%); endometrial (21%); myeloid leukemia (20%); myeloma (17%); colon (16%); head and neck (15%); rectal (13%); bladder (13%); and breast (10%).

Overall, there was a 7% lower risk of total cancers associated with a higher level of physical activity, and a majority of the associations remained consistent despite body size or smoking history.

“These findings support promoting physical activity as a key component of population-wide cancer prevention and control efforts,” said study authors.

Regions in the United States with higher levels of solar UV radiation were associated with a 27% higher risk of malignant melanoma compared to regions with lower levels. Additionally, physical activity was associated with a 5% higher risk of prostate cancer.

The biggest limitation of the study was that researchers were unable to completely exclude the possibility of smoking, diet, and additional factors that could affect the results. The study also used self-reported physical activity, which could result in errors in recall.

“In sum, these exciting findings by (researcher Steven C.) Moore (PhD, MPH) et al underscore the importance of leisure-time physical activity as a potential risk reduction strategy to decrease the cancer burden in the United States and abroad,” said Marilie D. Gammon, PhD, who coauthored a related commentary. “They demonstrate that high vs. low levels of physical activity engagement are associated with reduced risk of 13 cancer types (including 3 of the top 4 leading cancers among men and women worldwide). The widespread generalizability of these findings is reinforced by the suggestion that the associations persist regardless of BMI or smoking status.

“However, additional research, including more formal mediation analyses, on the underlying mechanisms for the recreational physical activity-cancer association should be pursued vigorously.”