Use of antibiotics may be linked to colon cancer risk later in life, particularly tumours in the proximal colon, according to a study of British patients.
The annual use of antibiotics continues to grow steadily, explains researcher Dr Cynthia Sears of Johns Hopkins University Baltimore, Maryland, USA, in Gut.
She believes that, given this widespread use of antibiotics, it is essential that their effects on gut microbiota and health outcomes is understood.
“Antibiotics, even narrow-spectrum antibiotics, exert strong, persistent effects on the structure of the gut microbiota and impairs the integrity of the intestinal barrier,” she writes. This allows for microbiome dysbiosis, she adds, and could lead to inflammation and tumours.
They used figures from the UK Clinical Practice Research Datalink from 1989 to 2012, covering 28,980 people with colorectal cancer and 137,077 without.
This showed that: “Oral antibiotic use was associated with colorectal cancer risk – but effects differed by anatomical location.
“The risk was observed after minimal use and was greatest in the proximal colon and with antibiotics with anti-anaerobic activity,” they report. “In contrast, an inverse association was detected between antibiotic use and rectal cancers, as compared with no antibiotic exposure.”
Specifically, penicillin were associated with increased risk of colon cancer whereas tetracyclines were linked to reduced risk of rectal cancer, according to the study.
They conclude that the different effects suggest “differences in gut microbiota and carcinogenesis mechanisms along the lower intestinal tract."
They write: “Whether antibiotic exposure is causal or contributory to colon cancer risk, our results highlight the importance of judicious antibiotic use by clinicians.”
Zhang, J. et al. Oral antibiotic use and risk of colorectal cancer in the United Kingdom, 1989-2012: a matched case-control study. Gut 21 August 2019; doi: 10.1136/gutjnl-2019-318593
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