Does hypertension increase mortality risk from lung cancer? A prospective cohort study on smoking, hypertension and lung cancer risk among Korean men

Objective: To examine the effects of hypertension on lung cancer prospectively and to determine the interactive effect of hypertension and smoking on lung cancer risk. Design: A prospective cohort study. Participants: The cohort comprised 452 645 Korean men, aged 35-64 years, who received health insurance from the Korea Medical Insurance Corporation and who had biennial medical evaluations in 1992 and 1994. Methods: Multivariate Cox proportional hazard models were tested, controlling for age, smoking status, exercise, body mass index, alcohol use, diabetes and serum cholesterol concentration. Main outcome measure: Deaths from lung cancer. Results: At baseline, 261 080 persons (58.3%) were identified as current cigarette smokers. Between 1995 and 1999, 883 deaths from lung cancer (44.8/100 000 person-years) occurred. An initial finding indicated that hypertension increased the mortality risk of lung cancer [risk ratio (RR) 1.3, 95% confidence interval (CI) 1.1-1.5]. However, after stratification for smoking status, the risk ratio was increased only for current smokers (RR 1.4, 95% CI 1.2-1.6). When the interaction term was included in the multivariate model, there was a significant interactive effect of hypertension with current smoking (RR 1.8, 95% CI 1.0-3.1) on the risk of death from lung cancer, whereas the effect of hypertension itself did not attain significance. Conclusion: Hypertension was not an independent risk factor in lung cancer-related deaths, but it increased the modest risk of lung cancer death among current smokers.