PhD Scientific Days 2024

Health Sciences II.

Alcohol Consumption, Smoking and Early-Onset Colorectal Cancer Risk: A Systematic Review and Meta-Analysis

Text of the abstract

Introduction: Colorectal cancer (CRC) is the third most common cancer worldwide. While screening programs have contributed to a decrease in colorectal cancer rates, the incidence of early-onset colorectal cancer (EOCRC) has lately been increasing. Recent studies showed that smoking is strongly associated with CRC in all ages, and that high alcohol consumption is particularly associated with EOCRC.
Aims: We aimed to investigate the association of smoking and alcohol consumption with EOCRC in a systematic review and meta-analysis.
Methods: Following preregistration of the study protocol in PROSPERO (CRD42023424149), we searched PubMed and Web of Science for observational studies on the association of smoking or alcohol consumption with EOCRC. Subsequently, two researchers independently screened the studies and extracted the data. We performed meta-analyses, including several subgroup analyses, to examine the association of alcohol consumption and smoking with the risk of EOCRC. Generally, random effects models were calculated, with fixed effect models employed for analyses including only a small number of studies. Data analysis was conducted using the metafor package in R version 4.2.2.
Results: We identified 14 studies for alcohol consumption and 17 for smoking. Alcohol use was found to be a risk factor for EOCRC, with a significant pooled odds ratio (OR) of 1.37 (95% confidence interval (CI) 1.12-1.67). A dose-response model revealed a positive trend between the amount of ethanol consumed per day and the risk of developing EOCRC.
As for smoking, the results of the main models were ambiguous. While ever smoking was found to be a significant risk factor for EOCRC with an OR of 1.47 (CI 1.24-1.74), neither current smoking (OR 1.02, CI 0.84-1.24), nor former smoking (OR 1.07, CI 0.83-1.38) were associated with EOCRC. Further subgroup analyses are planned to examine the heterogeneity in these models.
Conclusion: We found alcohol to be a significant risk factor for developing EOCRC. While smoking also appeared to be associated with an increased risk of EOCRC, these associations require further investigation. Such insights can inform prevention and screening approaches in colorectal cancer.
Funding: JW is supported the Federal Ministry of Education and Research (BMBF, grant number: 01KD2104B). UM is funded by the “Marga und Walter Boll Stiftung”.