From 2000–2010, global consumption of antibiotics rose by 35% up to 70 billion doses each year. Although doctors are more cautious to prescribe antibiotics now due to the fear of antibiotic resistance, if you do the math behind those numbers, it comes down to 10 doses per person per year for the entire planet. That’s a lot.
Which begs the question – what long-term consequences might antibiotics have on our health?
New research published in the journal Gut examines just that. The authors of the study write: "Our aim was to investigate the associations between antibiotic use and site-specific colorectal cancer risk in the world's largest primary care database."
The database they refer to is the Clinical Practice Research Datalink, which holds the medical records of 11.3 million people from 674 doctor's offices in the United Kingdom. The researchers looked at data from 1989–2012 from 19,726 people who developed colon cancer and 9,254 who developed rectal cancer. They also used data from 137,077 people who did not develop bowel cancer during that time period.
They then sorted the data, categorizing the antibiotics by drug class and the type of bacteria they target, and classifying the cancers by their positions (i.e. rectum, proximal colon and distal colon).
What they found was some mixed results: a clear association between antibiotic use but in distinct ways for colon versus rectal cancer. They saw an increase in colon cancer risk associated with antibiotic use, but a decrease in rectal cancer risk.
They also determined a statistically significant increase in colon cancer risk, most notably in the proximal colon, for antibiotics that target anaerobic bacteria rather than aerobic bacteria, reports Medical News Today.
Why that could be is still unclear. However, as the authors explain, "whether antibiotic exposure is causal or contributory to colon cancer risk, our results highlight the importance of judicious antibiotic use by clinicians."