Smoking and colorectal cancer: a pooled analysis of ten population-based cohort studies in Japan
Menée à partir des données de 10 études de cohortes japonaises incluant 363 409 participants au total (47 % d'hommes ; durée de suivi : 2,7 millions de personnes-années), cette étude analyse l'association entre le tabac et le risque de cancer colorectal (9 232 cas), en fonction du sexe et de l'intensité du tabagisme
Smoking has been consistently associated with the risk of colorectal cancer (CRC) in Western populations; however, evidence is limited and inconsistent in Asian people. To assess the association of smoking status, smoking intensity, and smoking cessation with colorectal risk in the Japanese population, we performed a pooled analysis of ten population-based cohort studies. Study-specific hazard ratios (HR) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards model and then pooled using a random effects model. Among 363,409 participants followed up for 2,666,004 person-years, 9,232 incident CRCs were identified. In men, compared with never smokers, ever smokers showed higher risk of CRC. The HRs (95% CI) were 1.19 (1.10-1.29) for CRC, 1.19 (1.09-1.30) for colon cancer, 1.28 (1.13-1.46) for distal colon cancer, and 1.21 (1.07-1.36) for rectal cancer. Smoking was associated with risk of CRC in a dose-response manner. In women, compared with never smokers, ever smokers showed increased risk of distal colon cancer (1.47 [1.19-1.82]). There was no evidence of a significant gender difference in the association of smoking and CRC risk. Our results confirm that smoking is associated with an increased risk of CRC, both overall and subsites, in Japanese men and distal colon cancer in Japanese women. This article is protected by copyright. All rights reserved.