Associations of smoking with early- and late-onset colorectal cancer

Abstract

AbstractBackgroundIncidence of colorectal cancer (CRC) in younger adults is increasing in many countries. Smoking is an established risk factor of CRC risk, but evidence on its impact on early-onset CRC (EOCRC) risk is limited. We aimed to evaluate the association of smoking exposure with EOCRC and compare it with late-onset CRC (LOCRC).MethodsSmoking history and other known or suspected CRC risk factors were ascertained in detail in personal interviews among 6264 CRC patients and 6866 controls (frequency matched for age, sex, and county of residence) who were recruited in 2003-2020 in the DACHS study (Darmkrebs: Chancen der Verhütung durch Screening [German]; Colorectal Cancer: Chances for Prevention Through Screening [English]), a population-based case-control study from Germany. Associations of smoking with EOCRC (<55 years, 724 cases, 787 controls) and LOCRC (≥55years, 5540 cases, 6079 controls) were estimated using multiple logistic regression.ResultsSmoking exposure was much higher among EOCRC cases than among controls, and strong associations of smoking were observed for both EOCRC and LOCR. Adjusted odds ratios for EOCRC and LOCRC were as follows: current smoking: 1.57 (95% confidence interval [CI] = 1.20 to 2.04, P < .001) and 1.46 (95% CI = 1.28 to 1.67, P < .001); former smoking: 1.39 (95% CI = 1.07 to 1.81, P = .01) and 1.24 (95% CI = 1.13 to 1.36, P < .001); per 10 pack-years: 1.15 (95% CI = 1.05 to 1.27, P < .001) and 1.05 (95% CI = 1.03 to 1.08, P < .001). These patterns were similar for colon and rectum cancer and for early- and late-stage CRC.ConclusionSmoking is a strong risk factor for both EOCRC and LOCRC.