Risk factors for lung cancer in never-smokers: Multi-cohort study

BackgroundIf lung cancer in never-smokers was a single disease entity, it would be the sixth most commonly occurring malignancy. Despite the population impact, its risk factors are poorly understood owing to a dearth of larger-scale, well-characterised studies. MethodsWe pooled individual-participant data from 18 prospective cohort studies comprising 91,588 never smokers (55,452 women) aged 16-102 years at study induction. Participants were linked to national death registries. ResultsA maximum of 17 years follow-up (mean 9.7) gave rise to 85 lung cancer deaths. Of the 19 potential determinants captured at baseline, only being older age (hazard ratio; 95% confidence interval per 10 year increase: 2.45; 2.11, 2.85), male (2.25; 1.46, 3.48), and having a high fruit and vegetable intake (2.29; 1.25, 4.17) were associated with elevated rates of lung cancer in this never-smoking group. No other substantial relationships were detected. ConclusionsDespite the number and breadth of potential risk factors featured in this multi-cohort study, there was no clear suggestion of new determinants of lung cancer in never-smokers. ImpactOur findings point to the need to explore the influence of risk factors additional to those included herein, particular in the field of genetics. Our unlikely finding for fruit and vegetable consumption warrants further testing.