Lifestyle factors and lung cancer risk among never smokers in the Canadian Partnership for Tomorrow's Health (CanPath).

Background: Although smoking is the primary risk factor for lung cancer, 15-25% of lung cancers occur in never smokers. Emerging evidence suggests lifestyle factors are associated with lung cancer risk, but few studies among never smokers exist.

Methods: A case-control study of never smokers within the Canadian Partnership for Tomorrow's Health was conducted. At recruitment, participants provided data on lifestyle, health history and sociodemographic factors. Incident lung cancers were identified through linkage with administrative health records. Cases (n = 190) were matched to controls (n = 760) on age, sex, and follow-up time. Logistic regression analyses, adjusted for matching factors and annual income, were used to identify associations between lifestyle factors and lung cancer risk.

Results: Consumption of < 5 servings of fruits and vegetables/day was associated with higher risk of lung cancer (OR  1.50, 95% CI 1.03-2.17). Short or long sleep (≤ 6 or > 9 h/night) was also associated with increased risk of lung cancer (OR 1.52, 95% CI 1.01-2.29). No associations were observed for obesity measures, alcohol consumption, or physical activity.

Conclusion: Our findings provide evidence of a potential role between sleep, fruits and vegetable consumption, and lung cancer risk in a pan-Canadian, non-smoking population. However, the sample size is modest, and further investigation is needed.