Physical activity and the risk of developing lung cancer among smokers: a meta-analysis.
Level 3 - non-randomized controlled study
Meta-analysis of observational cohort studies
PubMed 23528254 · doi:10.1016/j.jsams.2013.02.015
What was done
A computerized search of five databases was conducted to identify cohort studies examining physical activity intensity levels and lung cancer risk in baseline-free smokers. Two authors independently extracted data and assessed study quality. Pooled rate ratios (RR) were calculated overall and across subgroups of physical activity intensity, smoking status, and gender.
What was found
Pooled results from 7 cohort studies showed that physical activity was associated with a lower risk of lung cancer in smokers (RR = 0.82, 95% CI: 0.77–0.87). There was no evident dose-response gradient for activity intensity (high activity did not confer greater risk reduction than moderate activity) or smoking intensity (similar associations in light and heavy smokers). The risk reduction was significantly larger in women than in men (p = 0.03), but only one included study reported data on women.
Why it matters
These findings suggest that physical activity is linked to lower lung cancer risk among smokers, though it does not replace smoking cessation as a primary preventive measure.
Limits
The review included only 7 cohort studies, with total participant count omitted from the abstract. Observational designs are subject to residual confounding (such as unmeasured smoking exposure details or lifestyle factors). The gender subgroup finding was based on a single study, and no dose-response relationship was identified.
Cited by
- supports Exercise reduces the risk of lung cancer even among individuals who actively smoke.