Antibiotic Use and Increased Risk of Colorectal Cancers

Antibiotics, pills
Antibiotics, pills
Researches performed a meta-analysis to assess the influence of antibiotic use on the incidence of colorectal cancer.

The following article is a part of conference coverage from the Digestive Disease Week 2021 Annual Meeting , held virtually from May 21 to 23, 2021. The team at Gastroenterology Advisor will be reporting on the latest news and research conducted by leading experts in gastroenterology. Check back for more from DDW 2021.


A comprehensive meta-analysis substantiated the association of antibiotic use with increased risk of colorectal cancer. The results were presented at the Digestive Disease Week 2021 annual meeting.

A total of 12 observational studies met the inclusion criteria, 2 of which were cohort studies and 10 case-control that represented 125,837 cases of colorectal cancer. Any use of antibiotics was associated with significantly higher colorectal cancer risk compared with no antibiotic use. The overall odds ratio (OR) from the 10 case control studies was 1.21 (95% CI, 1.12-1.30) and the overall risk ratio (RR) from the 2 cohort studies was 1.15 (95% CI, 1.10-1.19).

The OR was 1.14 (95% CI, 0.71-1.81) for colon cancers and 1.46 (95% CI, 0.95, 2.23) for rectal cancers. The use of antiaerobic versus antianaerobic antibiotics was examined in 3 studies. Colorectal cancer risk was not increased with antiaerobic antibiotic use (OR, 1.00; 95% CI, 0.90-1.12). However, risk did increase with antianaerobic agent use (OR, 1.77; 95% CI, 1.17-2.67).

Several studies also examined risk based on antibiotic class. The use of penicillins (OR, 1.09; 95% CI, 1.04-1.14) and quinolones (OR, 1.16; 95% CI, 1.05-1.29) significantly increased colorectal cancer risk, respectively. The results were not significant for other antibiotic classes such as cephalosporins, macrolides, nitrofuran, nitroimidazole/metronidazole, sulphonamide/TMP-SMX, and tetracyclines. There were no detectable small study effects.

According to investigators, this is the most comprehensive meta-analysis to date and “substantiates that the use of antibiotics is associated with an increased risk of colorectal cancer and reinforces the importance of antibiotic stewardship.”

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Wang L, Zhou E, Mullin G. Antibiotic use increases the risk of colorectal cancer: a systematic review and meta-analysis. Poster presented at: Digestive Disease Week Annual Meeting; May 21-23, 2021. Abstract Su531.