The Effect of Cigarette Smoking on Bladder Cancer in Korean: A Prospective Cohort Study

Seo, Hyung Seok; Lee, Nam Kyu; Jee, Sun Ha

Abstract

PURPOSE: To verify the association between cigarette smoking and bladder cancer in the Korean population, as smoking is well known as a risk factor on bladder cancer. The risk of bladder cancer was compared among never-smokers, ex-smokers and current-smokers using a multivariate adjusted incidence rate and the mortality rate of bladder cancer of Koreans.
MATERIALS AND METHODS
A total of 348,010 participants were enrolled in this prospective study between 1993 (to 1994) and 2002. All participants completed a self administered questionnaire on cancer risk factors, including smoking habit. Follow up for incident bladder cancer was established. We classified all participants into three categories: current-smoker, ex-smoker and never-smoker, on the basis of their smoking habits. We confirmed bladder cancer from the data of the Korea National Cancer Registry and National Health Insurance Corporation up to (December?) 2002. The multivariate adjusted incidence and the mortality due to bladder cancer were used for both genders for a statistical analysis using a Cox proportional hazards model.
RESULTS
The incidence rate of bladder cancer per 100,000 persons in male never-smokers, ex-smokers and current-smokers were 27, 41 and 48, respectively, and the multivariate adjusted relative risks (RR) were 1.3 (95% confidence interval (CI), 0.9-2.0) and 1.7 (95% CI, 1.2-2.3) in ex- and current smokers, respectively. The incidence rate of bladder cancer in women was 4.7, 8.4 and 13, respectively. There was no significant association between the risk of bladder cancer and the amount and duration of smoking.
CONCLUSIONS
We concluded that current smokers have an increased incidence and mortality rate of bladder cancer in both genders in the Korean population, but there was no significant difference in relation to the amount and duration of smoking.