In a new study from Umeå University, Sweden, researchers found a clear link between taking antibiotics and an increased risk of developing colon cancer within the next five to ten years.
The impact of antibiotics on the intestinal microbiome is thought to lie behind the increased risk of cancer.
In the study, the team found that both women and men who took antibiotics for over six months ran a 17% greater risk of developing cancer in the ascending colon, the first part of the colon to be reached by food after the small intestine.
However, no increased risk was found for cancer in the descending colon. Nor was there an increased risk of rectal cancer in men taking antibiotics, while women taking antibiotics had a slightly reduced incidence of rectal cancer.
The increased risk of colon cancer was visible already five to ten years after taking antibiotics.
Although the increase in risk was greatest for those taking most antibiotics, it was also possible to observe an admittedly small, but statistically significant, increase in the risk of cancer after a single course of antibiotics.
The study uses data on 40,000 patients from the Swedish Colorectal Cancer Registry from the period 2010–2016.
These have been compared to a matched control group of 200,000 cancer-free individuals drawn from the Swedish population at large.
In order to understand how antibiotics increase the risk, the researchers also studied a non-antibiotic bactericidal drug used against urinary infections that do not affect the microbiome.
There was no difference in the frequency of colon cancer in those who used this drug, suggesting that it is the impact of antibiotics on the microbiome that increases the risk of cancer.
While the study only covers orally administered antibiotics, even intravenous antibiotics may affect the gut microbiota in the intestinal system.
The team says the increase in risk is moderate and the effect on the absolute risk to the individual is fairly small.
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.
If you care about colon cancer, please read studies about a new cause of colon cancer and findings of this stuff in mouth may cause colon cancer to spread.
For more information about colon cancer and your health, please see recent studies about common high blood pressure drugs may lower colon cancer risk and results showing that blue light at night linked to higher risk of colon cancer.
The study is published in JNCI: Journal of the National Cancer Institute. One author of the study is Sophia Harlid.
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