Cigarette smoking and the risk of colorectal cancer among men: a prospective study in Japan.
The association between cigarette smoking and the risk of colorectal cancer remains controversial. We examined this association using a population-based prospective cohort study in Miyagi, Japan. In 1990, we delivered a self-administered questionnaire on cigarette smoking and other health habits to 25 279 men who were 40-64 years of age and lived in 14 municipalities of Miyagi Prefecture. A total of 22 836 men responded (90.3% response rate). During 7 years of follow-up (158 376 person-years), we identified 188 patients of colorectal cancer. Relative risks and 95% confidence intervals were estimated by the Cox proportional-hazards regression analysis with adjustment for potential confounders. The multivariate-adjusted relative risks (95% confidence interval) of colorectal cancer for past smokers and current smokers compared with those who had never smoked were 1.73 (1.04-2.87) and 1.47 (0.93-2.34), respectively. Among current smokers, both a higher number of cigarettes smoked per day and an earlier age at which smoking had started were associated with a significant linear increase in risk (P for trend <0.05). Our findings are consistent with the hypothesis that cigarette smoking is associated with a higher risk of colorectal cancer in men.
Akhter
Munira
M
Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan. munira@mail.tains.tohoku.ac.jp
Nishino
Yoshikazu
Y
Nakaya
Naoki
N
Kurashima
Kayoko
K
Sato
Yuki
Y
Kuriyama
Shinichi
S
Tsubono
Yoshitaka
Y
Tsuji
Ichiro
I
D000328:Adult; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*