Unnecessary antibiotics may raise colon cancer risk — especially if younger, study says
Antibiotic use across the globe has been gradually increasing over the years. In the U.S., about 30% of prescribed antibiotics are considered unnecessary, totaling at about 47 million excess prescriptions a year.
Now, a new study suggests this surge in antibiotic use may be raising some people’s risk of developing colon cancer, particularly among those under 50 years old who are too young to be screened regularly for the disease.
Researchers speculate some antibiotics may be altering the microorganisms that live in people’s guts, but more study is needed to understand the true relationship between microbiomes and the infection fighting medications.
The findings don’t declare a cause and effect, rather just an association. Still, researchers advise antibiotics shouldn’t be prescribed unless absolutely necessary.
“To our knowledge, this is the first study to link antibiotic use with the growing risk of early onset colon cancer — a disease which has been increasing at a rate of at least 3% per year over the last two decades,” Sarah Perrott of the University of Aberdeen in the U.K. said during the ESMO World Congress on Gastrointestinal Cancer last week. “Junk food, sugary drinks, obesity and alcohol are likely to have played a part in that rise, but our data stress the importance of avoiding unnecessary antibiotics, especially in children and young adults.”
In a medical database of nearly 8,000 Scottish patients with bowel cancer and over 30,400 people without cancer, the researchers found antibiotic use was associated with a 50% increased risk of the disease in people younger than 50 years old compared to 9% in those over 50.
Specifically in the younger age group, antibiotic use — particularly the infection-treating quinolones, sulfonamides and trimethoprim — was associated with cancers found on the right side of the colon. This part of the colon contains more fluids and houses different natural bacteria than other parts of the organ.
“We don’t yet know if antibiotics can induce any effects on the microbiome that could directly or indirectly contribute to development of colon cancer,” study senior author Dr. Leslie Samuel, a physician at the Aberdeen Royal Infirmary, said in a statement. “It’s a complex situation as we know that the microbiome can quickly revert to its previous state even when the bowel has been cleared out for a diagnostic procedure such as an endoscopy.”
It doesn’t help that antibiotic use globally has increased 65% between 2000 and 2015, according to the researchers.
Another part of the problem is that younger patients tend to be diagnosed later in life when their cancer is harder to treat. Doctors are less likely to consider the disease when treating people with common symptoms such as abdominal discomfort if they are in their 30s, for example. Younger patients are also not eligible for bowel cancer screening under most guidelines.
A 2016 Centers for Disease Control and Prevention study found that of about 154 million antibiotic prescriptions written in doctor’s offices and emergency departments, 30% were unnecessary. Most of them were to treat acute respiratory conditions such as bronchitis, allergies, sinus infections, ear infections and pneumonia.
A year before the CDC study was conducted, the White House released The National Action Plan for Combating Antibiotic-Resistant Bacteria (CARB) in an effort to reduce “inappropriate outpatient antibiotic use” by at least half by 2020. It’s unclear if the U.S. met that goal.
This story was originally published July 6, 2021 at 1:03 PM with the headline "Unnecessary antibiotics may raise colon cancer risk — especially if younger, study says."
