Pre-Diagnosis Recreational Physical Activity and Lung Cancer Mortality within the California Teachers Study.

Purpose: Although physical activity (PA) levels have been linked to decreased lung cancer mortality, the magnitude of associations and delineation of biological and behavioral risk factors is often inconsistent. Our study aims to address this gap by elucidating the associations of lung cancer mortality with time-varying and exertion-varying pre-diagnosis PA levels. Methods: We examined the associations between PA and lung cancer mortality among 1,768 women enrolled in the California Teachers Study cohort and diagnosed with lung cancer between 1995-2019. Pre-diagnosis lifetime and recent PA were assessed. Multivariable Cox regressions provided hazard ratio (HR) and 95% confidence interval (CI) estimates. Results: Similar risks of lung cancer mortality were observed across all PA variables. Ever and/or former smokers who engaged in higher levels of moderate, lifetime PA had a lower risk of lung cancer mortality. Ever and/or current smokers who engaged in intermediate to high levels of strenuous, lifetime PA had increased risk of lung cancer mortality, while never smokers saw a protective effect on lung cancer mortality. Conclusion: The results of this study suggest that smoking significantly modifies the association between PA and lung cancer mortality. Although the mechanisms underlying these findings remain unclear, we hypothesize that excessive strenuous PA among ever and/or current smokers exacerbates the inflammatory damage already induced by smoke exposure, compromising immune cell recovery and leading to reduced lung cancer survival in this group.