RESUMEN
We aimed to investigate physical activity (PA) and risk of different histological subtypes of lung cancer according to smoking status and body mass index using repeated measurements in a large cohort of women in Norway. The study sample for the multiple imputation analyses consisted of 86,499 and for the complete-case analysis 80,802 women. Repeated measurements of PA level, smoking habits, weight, and height were available for 54,691 women (63.2%), who were included in repeated measurement analyses combined with multiple imputation to address attrition. Cox proportional hazards regression models were used to calculate hazard ratios with 95% confidence intervals. During a median follow-up of 12.9 years, 866 cases of primary lung cancer were identified. We found an inverse association between PA and lung cancer overall. The results were consistent from multiple imputed data analysis to complete-case analysis of PA and possible confounders. We observed a similar trend for adenocarcinoma, but not for squamous cell or small cell carcinomas. Our findings suggest a more pronounced association between lung cancer overall and PA levels in current and former smokers, and in normal-weight and overweight participants with increasing PA levels. The potential of a modifiable lifestyle factor as PA to reduce the risk of lung cancer independently of smoking status is important in public health.