Cigarette Smoking Associated with Colorectal Cancer Survival: A Nationwide, Population-Based Cohort Study

We investigate whether cigarette smoking is associated with survival in patients with colorectal cancer (CRC) through a nationwide population-based cohort study in Taiwan. The Taiwan Cancer Registry and National Health Insurance Research Database were used to identify data from patients with CRC from 2011 to 2017. Tobacco use was evaluated based on the smoking status, intensity, and duration before cancer diagnosis. A total of 18,816 patients was included. A Kaplan-Meier survival analysis indicated smoking to be significantly associated with the CRC mortality risk (log-rank p = 0.0001). A multivariable Cox model indicated that smoking patients had a 1.11-fold higher mortality risk (HR = 1.11, 95% CI = 1.05-1.19) than nonsmoking patients did. This increased risk was also present in patients with CRC who smoked 11-20 cigarettes per day (HR = 1.16; 95% CI = 1.07-1.26) or smoked for >30 years (HR = 1.14; 95% CI = 1.04-1.25). Stratified analyses of sex and cancer subsites indicated that the effects of smoking were higher in male patients and in those with colon cancer. Our results indicate that cigarette smoking is significantly associated with poor survival in patients with CRC. An integrated smoking cessation campaign is warranted to prevent CRC mortality.