Amount and Intensity of Leisure-Time Physical Activity and Lower Cancer Risk.
Level 3 - non-randomized controlled study
Pooled analysis of prospective cohort studies
PubMed 31877085 · doi:10.1200/JCO.19.02407
What was done
Data from 9 prospective cohort studies encompassing 755,459 participants (median age 62 years, range 32-91 years; 53% female) were pooled to evaluate associations between self-reported leisure-time physical activity and incidence of 15 cancer types. Multivariable Cox regression and restricted cubic spline models evaluated dose-response relationships at 7.5, 15.0, 22.5, and 30.0 MET hours/week compared to no leisure-time physical activity over a median follow-up of 10.1 years (50,620 incident cancers accrued).
What was found
Engagement 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: colon cancer in men (8%-14% lower risk), breast cancer (6%-10% lower risk), endometrial cancer (10%-18% lower risk), kidney cancer (11%-17% lower risk), myeloma (14%-19% lower risk), liver cancer (18%-27% lower risk), and non-Hodgkin lymphoma in women (11%-18% lower risk). Dose-response relationships were linear for half of the associations and nonlinear for the remainder. Results for moderate- and vigorous-intensity activity were mixed. Adjusting for body mass index eliminated the association with endometrial cancer but had limited effect on other cancers.
Why it matters
This pooled study provides large-scale evidence that achieving standard guideline levels of leisure-time physical activity is associated with lower risks across several common cancer sites.
Limits
Physical activity was self-reported, which is vulnerable to measurement error and recall bias. As an observational cohort study, residual confounding and reverse causation cannot be ruled out. No significant associations were observed for 8 of the 15 evaluated cancer types, and adjusting for body mass index fully attenuated the endometrial cancer association.
Cited by
- supports Cancer risk reduction benefits from exercise continue to accrue up to about 300 minutes per week, after which the curve plateaus.