A GWAS Suggesting Genetic Modifiers to Increase the Risk of Colorectal Cancer from Antibiotic Use

Background: Antibiotics have recently been suggested to increase the risk of colorectal cancer. Here, we aimed to investigate the association of frequent antibiotic use and genetic susceptibility with the increased risk of the development of colorectal cancer. Therefore, a genome-wide association study was conducted in colorectal cancer patients with frequent antibiotic use and controls to identify potential chromosomal regions that could indicate an increased risk of colorectal cancer associated with antibiotic use. The results were replicated with a case-case analysis.

Methods: A genome-wide case-control study involving 143 colorectal cancer cases with frequent exposure to antibiotics and 1642 healthy individuals with unknown antibiotic use was undertaken. A logistic regression model was used to identify associations between certain chromosomal regions (loci) and the risk of colorectal cancer in cases with frequent antibiotic use. The results were replicated in a follow-up association case-case study comparing the frequent users to those with a more modest use of antibiotics.

Results: Six chromosomal regions were associated with colorectal cancer in patients exposed to frequent antibiotic use. Two of the six regions contained genes already suggested to be associated with colorectal cancer tumorigenesis, epithelial-mesenchymal transition and colorectal cancer recurrence. The results for the six chromosomal regions were further replicated in a case-case analysis where all the chromosomal regions were confirmed with high odds ratios (ORs) supporting the hypothesis that frequent antibiotic use is associated with an increased risk of colorectal cancer development.

Conclusions: The study suggested that genetic modifiers could influence the risk of colorectal cancer associated with the frequent use of antibiotics.