Cigarette smoking and cancer incidence risk in adult men: National Health Insurance Corporation Study

We analyzed risk while adjusting for age, body mass index, frequency of moderate physical activity, alcohol consumption, preference for vegetables versus meats, and frequency of meat consumption in a multivariate analysis and based our findings on not mortality data but incidence data. 733,134 Korean men who were 30 years old or older, insured by the National Health Insurance Corporation, and had a medical evaluation in 1996 were included in the study and followed up through 2000. During the 4-year follow-up period of 3,590,872 person-years, we identified 7204 new cases. We used the Cox proportional hazards model to estimate adjusted relative risks (aRRs), 95% confidence intervals (CIs). The association of current cigarette smoking was significantly stronger as compared with never smokers; aRR was 1.49 (95% CI = 1.39-1.59) for all cancers, 4.46 (2.32-8.57) for esophageal, 3.83 (2.97-4.94) for lung, 3.01 (1.58-5.72) for laryngeal, 2.24 (1.48-3.39) for urinary bladder, 1.62 (1.42-1.84) for gastric, 1.75 (1.12-2.74) for oral and pharyngeal, 1.58 (0.97-2.27) for pancreatic, and 1.50 (1.29-1.74) for liver cancer. Our findings, based on incidence data, confirmed that differences in smoking habit were responsible for most of the differences observed in smoking-related cancers.