Association of Leisure-Time Physical Activity With Risk of 26 Types of Cancer in 1.44 Million Adults.
Level 3 - non-randomized controlled study
Pooled analysis of prospective observational cohort studies
PubMed 27183032 · doi:10.1001/jamainternmed.2016.1548
What was done
Data were pooled from 12 prospective US and European cohorts enrolled between 1987 and 2004, comprising 1.44 million adults (median age 59 years, range 19–98; 57% female; 186,932 incident cancer cases). Self-reported moderate-to-vigorous leisure-time physical activity was standardized to cohort-specific percentiles. Multivariable Cox proportional hazards regression and random-effects meta-analyses were used to evaluate associations between physical activity levels (comparing the 90th vs 10th percentile) and incidence across 26 cancer types, adjusting for confounders including body mass index (BMI) and smoking status.
What was found
High versus low physical activity (90th vs 10th percentile) was associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR 0.58; 95% CI, 0.37–0.89), liver (HR 0.73; 95% CI, 0.55–0.98), lung (HR 0.74; 95% CI, 0.71–0.77), kidney (HR 0.77; 95% CI, 0.70–0.85), gastric cardia (HR 0.78; 95% CI, 0.64–0.95), endometrial (HR 0.79; 95% CI, 0.68–0.92), myeloid leukemia (HR 0.80; 95% CI, 0.70–0.92), myeloma (HR 0.83; 95% CI, 0.72–0.95), colon (HR 0.84; 95% CI, 0.77–0.91), head and neck (HR 0.85; 95% CI, 0.78–0.93), rectal (HR 0.87; 95% CI, 0.80–0.95), bladder (HR 0.87; 95% CI, 0.82–0.92), and breast cancer (HR 0.90; 95% CI, 0.87–0.93). BMI adjustment modestly attenuated associations, with 10 remaining statistically significant. Physical activity was associated with higher risks of malignant melanoma (HR 1.27; 95% CI, 1.16–1.40) and prostate cancer (HR 1.05; 95% CI, 1.03–1.08).
Why it matters
This pooled analysis extends the known protective associations of physical activity beyond breast and colon cancers to a wide range of common malignancies, showing benefits that are largely independent of body weight.
Limits
Physical activity was self-reported at baseline, making exposure assessment susceptible to recall bias and unable to capture changes over time. Residual confounding remains possible, including sun exposure for melanoma and higher screening rates for prostate cancer. The sample was restricted to US and European cohorts.
Cited by
- supports Exercise has been shown to reduce the risk of 8 to 10 specific cancer types, including colon, breast, endometrial, stomach, and esophageal cancer.
- supports Exercise lowers cancer risk independently of obesity status, showing risk reductions even in individuals with a BMI over 30 who do not lose weight.
- supports There is a dose-response relationship between exercise volume and cancer risk reduction, where more physical activity correlates with greater risk reduction.
- supports In cancer prevention epidemiology, physical activity shows the strongest protective associations with colon and breast cancers, but little association with rectal or prostate cancers.
- supports Individuals who regularly exercise have higher rates of skin cancer than non-exercisers due to increased sun exposure.