Doctors and patients are advised to reduce unnecessary use of antibiotics following new data, published in Annals of Oncology, suggesting that these drugs may increase the risk of cancer of the large intestine (colon), especially in people under the age of 50.
Using a large Scottish primary care database of up to 2 million people, the study looked at nearly 8,000 people with associated bowel (colon and rectum) cancer. to people without bowel cancer. It found that antibiotic use was associated with an increased risk of colon cancer at all ages, but the risk was increased by almost 50% in those under 50 compared to 9% in those over 50. . In the younger age group, antibiotic use has been linked to cancers in the first part of the colon (the right side). Quinolones and sulfonamides / trimethoprim, which are used to treat a wide range of infections, have been linked to these right-sided cancers.
Lead author Dr Leslie Samuel of the Aberdeen Royal Infirmary explained that the contents of the right side of the colon are more liquid and that the natural bacteria that live there, called the microbiome, may be different from those located further away. in the colon.
“We now want to know if there is a link between antibiotic use and changes in the microbiome that can make the colon more susceptible to cancer, especially in young people,” said Dr Samuel. âIt’s a complex situation because we know that the microbiome can quickly return to its previous state, even after the intestine has been emptied for a diagnostic procedure such as endoscopy. We don’t yet know if antibiotics can induce effects on the microbiome that could directly or indirectly contribute to the development of colon cancer.
The study was presented at the 2021 ESMO World Gastrointestinal Cancer Congress by Sarah Perrott of the University of Aberdeen, who claimed that it was “the first study to link antibiotic use and the increasing risk of early-stage colon cancer – a disease that has been increasing at a rate of at least 3% per year for the past two decades â.
“Junk food, sugary drinks, obesity, and alcohol probably played a role in this increase, but our data underscores the importance of avoiding unnecessary antibiotics, especially in children and young adults,” he said. Perrott said.
Commenting on the new research, Professor Alberto Sobrero of Ospedale San Martino noted that young people between the ages of 20 and 40 with colon cancer generally have a poorer prognosis than older people because they are often diagnosed later.
“Doctors are less likely to investigate a patient with abdominal discomfort for colon cancer if they are in their 30s than if they are 70, and younger patients are not eligible for cancer screening of the intestine. As a result, their cancer is usually diagnosed at a later stage, when it is more difficult to treat, âhe said.
He believes doctors should now think about bowel cancer in younger patients with abdominal symptoms, and supports more research into the multiple possible causes of the rising incidence of colon cancer in this age group.
“It is too early to say if the excessive use of antibiotics could be a causal factor, and we need to better understand the possible role of the microbiome in bowel cancer before considering the impact of antibiotics on the flora. intestinal, âhe said. “However, the new research reminds us that antibiotics should not be given unless they are really needed, and we cannot rule out the possibility that unnecessary use of antibiotics may put people at increased risk. cancer. “
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