Oral antibiotic use is associated with an increased risk of colon cancer but a reduced risk of rectal cancer, and depends, to some extent, on the drug class prescribed, suggests new research published in the journal Gut.
A matched case-control observational study was performed using the UK Clinical Practice Research Datalink from 1989 to 2012 to assess the association between oral antibiotic consumption and colorectal cancer (CRC) risk, identifying 28,980 CRC cases and 137,077 controls.
Antibiotics had been prescribed to 70.0% of CRC patients versus 68.5% of controls (P
Antibiotic use increased colon cancer risk in a dose-dependent fashion (P
In contrast, an inverse association was detected between antibiotic use and rectal cancers (P=0.003), particularly with length of antibiotic exposure >60 days (adjusted odds ratio (aOR)=0.85; 95% CI 0.79-0.93) as compared with no antibiotic exposure.
Penicillins, particularly ampicillin/amoxicillin, increased colon cancer risk (aOR=1.09 (1.05-1.13)), whereas tetracyclines reduced rectal cancer risk (aOR=0.90 (0.84-0.97)).
The findings suggest a pattern of risk that may be linked to differences in gut microbiome activity and carcinogenesis mechanisms along the lower intestinal tract, with antimicrobial prescribing ramifications, the researchers concluded.