[Relation between waist circumference and risk of male lung cancer incidence: a prospective cohort study]

Objective: To investigate the association between waist circumference and risk of male lung cancer incidence. Methods: Since May 1, 2006, all the male employees including the retirees in Kailuan Group had been recruited into a Chinese Kailuan Male Cohort study. Information on anthropometries including body weight, height and waist circumference were collected at the baseline investigation, as well as information on newly-diagnosed lung cancer cases during the follow-up period. Waist circumference was grouped by quintiles of the population waist circumference distribution and categorized into the following five groups: <80, 80-, 85-, 90- and ≥95 cm, with the relevant normal group, the second quintile group (80-cm), serving as the referent category. Multivariable Cox proportional hazards regression models were used to evaluate the association between levels of waist circumference and risk of lung cancer. Results: A total of 105 386 males were recruited in the study, with 739 651.13 person-years of follow-up and an average follow-up period of 7.00 years. By the end of 2014, a total of 707 lung cancer cases were identified in the cohort study. Compared with males having the 80-cm of waist circumference, the hazard ratio (HR) and 95% confidence intervals (CI) of lung cancer were 1.17(0.90-1.52), 0.96(0.74-1.23), 0.94(0.72-1.21) and 0.80(0.63-1.03) for the <80, 85-, 90- and ≥95 cm of waist circumference, after adjustment for potential confounding factors including age, education level, smoking status and pack-year amount, alcohol consumption, physical activities, environment for working place and the prevalence on diabetes. The inverse association existed in smokers (≥95 cm compared to 80-cm of waist circumference: HR=0.69, 95%CI: 0.48-0.99) and alcohol drinkers (≥95 cm compared to 80-cm of waist circumference: HR=0.65, 95%CI: 0.45-0.94) when analysis was conducted in subgroups stratified by smoking or alcohol drinking status. Conclusion: Waist circumference might be inversely associated with male lung cancer risk.