- Increased physical activity was associated with reduced risk for lung cancer, according to a meta-analysis, but was only significant among current smokers.
Why this matters
- Prior studies that found an association between exercise and lung cancer risk left unclear whether that association was caused by an underestimation of lifetime smoking.
- Meta-analysis of 20 cohort studies with 2,965,811 individuals, including 31,807 who developed lung cancer during follow-up.
- Funding not disclosed.
- Increased physical activity was associated with reduced lung cancer risk compared with low-level physical activity (relative risk [RR], 0.83; 95% CI, 0.77-0.90).
- High-level physical activity was associated with reduced risk in women (RR, 0.90; 95% CI, 0.82-0.99) and men (RR, 0.81; 95% CI, 0.73-0.90) compared with low-level physical activity.
- A high level of physical activity was significantly associated with reduced lung cancer risk in current smokers (RR, 0.90; 95% CI, 0.84-0.97), but the association was not significant in nonsmokers (RR, 0.95; 95% CI, 0.88-1.03).
- Reduced risk was significantly lower in subgroups unadjusted for dietary factors (RR, 0.74; 95% CI, 0.71-0.77) compared with those adjusted for dietary factors (aRR, 0.89; 95% CI, 0.84-0.95).
- No data on chronic lung disease or total energy intake.