Leisure-time physical activity and risk of 26 types of cancer in 1.44 million adults

Abstract

IMPORTANCE

Leisure-time physical activity has been associated with lower risk of heart-disease and all-cause mortality, but its association with risk of cancer is not well-understood.

OBJECTIVE

To determine the association of leisure-time physical activity with incidence of common types of cancer and whether associations vary by body size and/or smoking.

DESIGN, SETTING, AND PARTICIPANTS

We pooled data from 12 prospective U.S. and European cohorts with self-reported physical activity (baseline 1987–2004). A total of 1.44 million participants (median age:59 years; range:19–98 years) and 186,932 cancers were included. We used multivariable Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of leisure-time physical activity with incidence of 26 types of cancer. Leisure-time physical activity levels were modeled as cohort-specific percentiles on a continuous basis and cohort-specific results were synthesized by random effects meta-analysis. Hazard ratios for high versus low levels of activity are based on a comparison of risk at the 90 ^th versus 10 ^th percentiles, respectively, of activity.

EXPOSURE

Leisure-time physical activity of a moderate to vigorous intensity.

MAIN OUTCOMES AND MEASURES

Incident cancer during follow-up.

RESULTS

High versus low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR=0.58,CI:0.37–0.89), liver (HR=0.73,CI:0.55–0.98), lung (HR=0.74,CI:0.71–0.77), kidney (HR=0.77,CI:0.70–0.85), gastric cardia (HR=0.78,CI:0.64–0.95), endometrial (HR=0.79,CI:0.68–0.92), myeloid leukemia (HR=0.80,CI:0.70–0.92), myeloma (HR=0.83,CI:0.72–0.95), colon (HR=0.84,CI:0.77–0.91), head and neck (HR=0.85,CI:0.78–0.93), rectal (HR=0.87,CI:0.80–0.95), bladder (HR=0.87,CI:0.82–0.92), and breast (HR=0.90,CI:0.87–0.93). BMI adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after BMI adjustment. Leisure-time physical activity was associated with higher risks of malignant melanoma (HR=1.27,CI:1.16–1.40) and prostate cancer (HR=1.05,CI:1.03–1.08). Associations were generally similar between the overweight/obese and the normal weight. Smoking status modified the association for lung cancer, but not other smoking-related cancers.

CONCLUSIONS AND RELEVANCE

In addition to associations with lower risk of heart-disease and mortality, leisure-time physical activity is also associated with lower risks of many cancer types. Health care professionals counseling inactive adults should emphasize that most of these associations were evident regardless of body size or smoking history, supporting broad generalizability of findings.