Antibiotic Use May Increase the Risk of Colon Cancer, Study Warns

According to the findings of a new study, long courses of antibiotics may increase an individual’s risk of developing colon cancer, adding to concerns within the medical community about overuse of the drugs, which may also lead to the emergence of antibiotic-resistant “superbug” infections.

In a report published this month in the Journal of the National Cancer Institute, researchers warn that use of antibiotics for more than six months had the highest increased risk of colon cancer, but even shorter regimens of antibiotics increase the risk of cancer.

Swedish researchers conducted a nationwide population-based study with a matched case-controlled design, using data from the Swedish Prescribed Drug Register from 2005 to 2016, and matching a total of 40,545 patients with colorectal cancer to more than 202,000 control patients without cancer.

The data indicates antibiotic use may increase the risk of developing colorectal cancer, especially among frequent users or long-term users. Patients who took antibiotics for more than six months had a 17% increased risk of developing colon cancer; the highest cancer risk compared to those who took no antibiotics.

The findings indicate quinolone and sulfonamides and trimethoprim class of antibiotics were positively linked with colon cancer.

Researchers believe the risk of colon cancer may be increased by how antibiotics change the gut microbiome. Antibiotics may disrupt the balance of the microbiome and allow infectious bugs like E. coli and Klebsiella pneumoniae to proliferate. This can lead to inflammation in the colon, which may lead to damaged DNA and the generation of tumors.

The study also speculates the inner lining of the intestine may become more permeable and allow bacteria to enter the colon walls and join with the biofilm in the intestines. Roughly 90% of colon cancers are linked with biofilms.

The increased risk of cancer is specific to the proximal colon, the part of the colon that connects to the small intestine and starts in the lower-right abdomen, also known as the ascending colon. The ascending colon extends from the lower to upper right abdomen.

While the study’s findings show an increased risk of colon cancer linked to antibiotic use, the data also indicated there was an inverse risk linked with rectal cancer, especially in the female population, meaning it decreased the risk.

The data from this study appears to support findings of another study published earlier this year, which pointed to widespread antibiotic use increasing colon cancer rates.

The studies’ findings add to the list of reasons many say the medical community should address the overuse of antibiotics. In addition to potential cancer risks, the unnecessary use of the medications also contributes to the proliferation of antibiotic resistant bacteria.

Previous research has warned that antibiotic-resistant bacteria could kill more than 10 million people every year by 2050 if measures are not implemented to reduce unnecessary prescribing.