BMI changes and the risk of lung cancer in male never-smokers: A prospective cohort study.

Background: To investigate the association between the risk of lung cancer and short-term body mass index (BMI) changes in male never-smokers of a large population-based prospective study.

Methods: A total of 37,085 male never-smokers from Kailuan cohort with at least ≥2 BMI measurements were recruited in the present study. The BMI change in the follow-up was calculated as the annual percent change between BMI at last examination and that at baseline, and categorized into five groups: stable (-0.1 to <0.1 kg/m /year), minor loss (-1.0 to <0.1 kg/m /year) or gain (0.1 to <1.0 kg/m /year), and major loss (<-1.0 kg/m /year) or gain (≥1.0 kg/m /year). The hazards ratios (HRs) and its 95% confidence intervals (CI) were estimated using Cox regression models.

Results: During a median follow-up of 5.16 years, 224 lung cancer cases were identified. We found a U-shaped association between BMI changes and lung cancer risk. Compared to men with stable BMI, those with major loss had a nearly twofold higher risk of lung cancer (HR = 1.97, 95% CI: 1.12-3.45), as well as those with major gain had more than twofold higher risk of lung cancer (HR = 2.15, 95% CI: 1.15-4.02). The associations existed when the analysis was stratified by BMI, waist circumference and blood lipids, and lipoproteins concentration at baseline examination.

Conclusions: The dramatic changes in BMI, both gain and loss, might increase lung cancer risk. The control of body weight would be a potential way for lung cancer prevention especially for the nonsmokers.