The use of antibiotics may be a cause of colon cancer

cause of colon cancer
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A team of Swedish researchers has identified that the use of antibiotics is a potential cause of colon cancer, exacerbating the risk of developing the deadly disease.

In a study conducted at the Umeå University, Sweden, researchers have discovered that antibiotics use may cause colon cancer, finding that within five to 10 years of being administered the medicine, patients’ risk of developing the disease was increased.

The groundbreaking study analysed 40,000 cancer cases, from which the team distinguished that antibiotics have a detrimental impact on the intestinal microbiome, a process that is believed to be a cause of colon cancer.

Sophia Harlid, a cancer researcher at Umeå University, said: “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. Above all to prevent bacteria from developing resistance but, as this study shows, also because antibiotics may increase the risk of future colon cancer.”

Examining the impacts of antibiotics

To conduct their study, the team employed data from the Swedish Colorectal Cancer Registry on 40,000 patients between 2010 to 2016, which they then compared to a matched control group of 200,000 cancer-free individuals that were drawn randomly from the Swedish population. Subsequently, the researchers attained data of the individuals’ use of antibiotics between 2005 and 2016 from the Swedish Prescribed Drug Register.

Exacerbating the development of colon cancer

The results of the study signified that both men and women who were administered antibiotics for a period of six months had a 17% higher chance of developing cancer in the ascending colon – the primary part of the colon that food reaches after the small intestine – than those who were not prescribed antibiotics. Interestingly, antibiotics were found not to be a cause of colon cancer in the descending colon.

Furthermore, the risk of rectal cancer in men was identified not to be increased by antibiotics, with women displaying a slightly reduced incidence of rectal cancer on antibiotics. The team found that the risk of colon cancer was visible within five to 10 years of taking antibiotics, and despite the most significant risk being in those taking a large amount of the medication, there was a small but statistically significant increase in the risk of colon cancer after a single course of antibiotics.

To analyse why antibiotics may be a cause of colon cancer, the team examined a non-antibiotic bactericidal drug employed to combat urinary infections that do not affect the microbiome. They ascertained that there was no difference in the frequency of colon cancer in people who used this drug, indicating that the use of antibiotics on the microbiome increases the risk of colon cancer. Although the investigation only analysed orally administered antibiotics, the researchers believe that even intravenous antibiotics may affect the intestinal system’s gut microbiota.

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


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