Study Results Link Antibiotics to Increased Colon Cancer Risk

Umeā University in Sweden finds a connection between the two, due to the intestinal micobiome.

Antibiotics have been linked with an increased risk of colon cancer due to the intestinal microbiome that is thought to lie behind increased cancer risk, according to the results of a study conducted by investigators at Umeā University in Sweden.

“The results underline the fact that there are many reasons to be restrictive with antibiotics. While in many cases antibiotic therapy is necessary and saves lives, in the event of less serious ailments that can be expected to heal anyway, caution should be exercised,” Sophia Harlid, a cancer researcher at Umeå University, said in a statement. “Above all to prevent bacteria from developing resistance but, as this study shows, also because antibiotics may increase the risk of future colon cancer.”

Within 5 to 10 years after taking antibiotics, the increased risk of colon cancer was apparent, according to the statement.

Individuals who took antibiotics for more than 6 months had a 17% increase of cancer in the ascending colon, which is the first part of the colon that food reaches after the small intestine.

However, there was no increased risk in the descending colon or rectal cancer in men.

Rectal cancer in women had a slightly reduced risk, according to the statement.

The study conducted by the university also found that there was still a “small but statistically significant” increase of risk in cancer after 1 course of antibiotics, according to the statement.

“There is absolutely no cause for alarm simply because you have taken antibiotics. The increase in risk is moderate, and the effect on the absolute risk to the individual is fairly small,” Harlid said.

“Sweden is also in the process of introducing routine screening for colorectal cancer. Like any other screening program, it is important to take part so that any cancer can be detected early or even prevented, as cancer precursors can sometimes be removed,” Harlid said.

There is also evidence that shows that non-antibiotic bactericidal drugs for urinary tract infections do not affect the microbiome, suggesting that antibiotics that affect the microbiome are the ones with an increased risk of colon cancer.


Antibiotics increase the risk of colon cancer. EurekAlert. News alert. September 1, 2021. Accessed September 1, 2021.