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

Menée en Allemagne sur la période 2003-2020 par entretien auprès de 6 866 témoins et 6 264 patients atteints d'un cancer colorectal, cette étude analyse l'association entre une exposition au tabagisme et le risque de survenue précoce ou tardive de la maladie

Résumé en anglais

Incidence 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).Smoking history and other known or suspected CRC risk factors were ascertained in detail in personal interviews among 6,264 CRC patients and 6,866 controls (frequency matched for age, sex and county of residence) who were recruited in 2003-2020 in the DACHS study, 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.Smoking 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 (95% confidence intervals, P) for EOCRC and LOCRC were: current smoking: 1.57 (1.20-2.04, P< .001) and 1.46 (1.28-1.67, P< .001); former smoking: 1.39 (1.07-1.81, P=.01) and 1.24 (1.13-1.36, P< .001); per 10 pack-years: 1.15 (1.05-1.27, P< .001) and 1.05 (1.03-1.08, P< .001). These patterns were similar for colon and rectum cancer and for early and late stage CRC.Smoking is a strong risk factor for both EOCRC and LOCRC.