Body Mass Index, Height, Weight Change, and Subsequent Lung Cancer Risk: The Japan Public Health Center-Based Prospective Study

Background: Body mass index (BMI) is inversely associated with lung cancer risk, while residual confounding by smoking or weight change is controversial. Evidence on height and lung cancer is scarce. Methods: We investigated the associations between anthropometrics, BMI, and height, and incidence of lung cancer among 92,098 study subjects (44,158 men and 47,940 women) in the Japan Public Health Center-based Prospective Study. Cox proportional hazards regression was performed with adjustment for potential confounders and by cancer subtypes and smoking status. Information on weight and height was self-reported at baseline, and validated using measured health check-up data. Results: During follow-up between 1990 and 2013 (average, 19.1 years), a total of 2,152 lung cancer cases were newly diagnosed. In a multivariate regression model, lower BMI was positively associated with overall lung cancer risk [<19 kg/m(2) HR = 1.48; 95% confidence interval (CI) = 1.18-1.85 and 19-22.9 kg/m(2) HR = 1.19; 95% CI = 1.05-1.35; Ptrend = <0.001] in men. The risk estimate was also elevated for adenocarcinoma in the BMI < 19 kg/m(2) category and for squamous cell carcinoma among men in the 19-22.9 kg/m(2) BMI category. An association was also observed between low BMI, weight decrease, and squamous cell carcinoma in women. No significant associations were observed for other weight categories, height, weight change and lung cancer, adenocarcinoma, squamous and small cell carcinoma. Conclusions: Our prospective study suggests that lower BMI may be associated with an increased risk of smoking-related lung cancer in Japan, irrespective of gender. Impact: This study highlights the association between lower BMI and the risk of lung cancer in men.