A pooled analysis of nine prospective studies involving more than 750,000 adults has found that recommended amounts of leisure-time physical activity were linked to a lower risk for seven cancers, with several cancer types having a dose/response relationship. These findings were published by Matthews et al in the Journal of Clinical Oncology.

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While it’s known that physical activity is associated with a lower risk of several cancers, more information on the relationship and whether recommended amounts of physical activity are associated with lower risk were not as well-known. Updated guidelines for activity now state that people should aim for 2.5–5 hours a week of moderate-intensity activity or 1.25–2.5 hours a week of vigorous activity. Moderate-intensity activities are those that get you moving fast enough or strenuously enough to burn off three to six times as much energy per minute as sitting quietly (3 to 6 metabolic equivalent task [METs]). Vigorous-intensity activities burn more than 6 METs.

Study Results

For the current analysis, investigators pooled data from nine prospective cohorts with self-reported leisure-time physical activity and follow-up for cancer incidence, looking at the relationship between physical activity with incidence of 15 types of cancer.

They found engaging in recommended amounts of activity (7.5–15 MET hours/week) was associated with a statistically significant lower risk of 7 of the 15 cancer types studied, with the reduction increasing with more MET hours. Physical activity was associated with a lower risk of colon cancer in men (8% for 7.5 MET hours/week; 14% for 15 MET hours/week), female breast cancer (6%; 10%), endometrial cancer (10%; 18%), kidney cancer (11%; 17%), myeloma (14%; 19%), liver cancer  (18%; 27%), and non-Hodgkin lymphoma (11%; 18% in women). The dose response was linear in shape for half of the associations and nonlinear for the others.

The analysis had some limitations. Even with 750,000 participants, patient numbers were limited for some cancers; participants were primarily white; there was a limited number of cohorts with detailed physical activity measures; and the authors relied on self-reported physical activity.

The authors concluded, “Health care providers, fitness professionals, and public health practitioners should encourage adults to adopt and maintain physical activity at recommended levels to lower risks of multiple cancers.”

Charles E. Matthews, PhD, of the National Cancer Institute, Division of Cancer Epidemiology and Genetics, Metabolic Epidemiology Branch, Bethesda, Maryland, is corresponding author for the Journal of Clinical Oncology article.

Disclosure: For full disclosures of the study authors, visit ascopubs.org.