Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: systematic review and dose-response meta-analysis for the Global Burden of Disease Study 2013.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of prospective observational cohort studies
PubMed 27510511 · doi:10.1136/bmj.i3857
What was done
Systematic review and Bayesian dose-response meta-analysis of prospective cohort studies from PubMed, Embase (1980 to February 2016), and relevant review reference lists. Domain-specific physical activity was mapped to total activity in metabolic equivalent (MET) minutes per week using population data from the Study on Global AGEing and Adult Health and US NHANES. Outcomes assessed were risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events.
What was found
The review identified 174 articles (35 for breast cancer, 19 for colon cancer, 55 for diabetes, 43 for ischemic heart disease, and 26 for ischemic stroke). Major risk reductions occurred up to 3000 to 4000 MET minutes/week. For diabetes, 600 MET minutes/week versus no activity lowered risk by 2%, increasing from 600 to 3600 MET minutes/week reduced risk by an additional 19%, and increasing from 9000 to 12000 MET minutes/week reduced risk by 0.6%. Comparing highly active individuals (8000 or more MET minutes/week) with insufficiently active individuals (less than 600 MET minutes/week), relative risks were 0.863 (95% uncertainty interval 0.829 to 0.900) for breast cancer, 0.789 (0.735 to 0.850) for colon cancer, 0.722 (0.678 to 0.768) for diabetes, 0.754 (0.704 to 0.809) for ischemic heart disease, and 0.736 (0.659 to 0.811) for ischemic stroke.
Why it matters
Achieving physical activity levels several times above the current recommended minimum (600 MET minutes/week) yields substantially greater reductions in the risk of major chronic diseases, with diminishing marginal benefits at very high volumes.
Limits
All included studies were observational cohorts subject to residual confounding and exposure misclassification. Physical activity was mapped from domain-specific self-reports using external surveys rather than objectively measured in every cohort. Total participant sample size is not reported in the abstract.
Cited by
- supports Epidemiological and clinical evidence shows that regular exercise reduces the risk of breast cancer and colon cancer.