Widespread Antibiotic Use May Be Increasing Colon Cancer Rates: Study

The findings of new research raise further concerns about the side effects of overprescribing and overusing antibiotics, indicating unnecessary prescriptions may increase the risk of developing colon cancer among both young and older patients.

Antibiotic use has increased drastically over the past 20 years, greatly owing to doctor overprescribing, which has raised concerns in recent years about the emergency of “superbug” infections that are resistant to existing antibiotics. However, Scottish researchers now indicate the practice may be linked to corresponding increases in the occurrence of colon and rectal cancer cases.

Researchers with the University of Aberdeen conducted a nested case-control study of patients belonging to Scottish primary care doctors, using information from a database that included 7,900 colorectal cancer cases, 5,200 colon cancer cases and 2,600 rectal cancer cases. Patients were diagnosed from 1999 to 2011, and matched with more than 30,000 control patients.

Of the patients with colorectal cancer, 45% were prescribed antibiotics. Nearly 500 were under the age of 50 when they were diagnosed.

The data indicates antibiotic use was associated with an increased risk of proximal colon cancer in patients under 50 years old, but not among patients older than 50.

The findings also revealed quinolone, the active ingredient in Levaquin, and sulfonamides/trimethoprim, like Bactrim and Primsol, were associated with proximal colon cancer in the early-onset group.

Overall, using any type of antibiotic was linked with an increased risk of colon cancer in both patients over 50 and under 50 years old. The risk was increased for quinolone and sulfonamide/trimethoprim antibiotics.

Researchers believe the widespread overuse of antibiotics significantly alters the microbiome in the gut, which may lead to colorectal cancer in adults. Prior research has shown many doctors, especially those in urgent care clinics, overprescribe antibiotics to patients with ailments that cannot be treated with antibiotics.

Cases of colorectal cancer have increased among young, non-obese patients with no risk factors in recent years. Researchers hope the findings of this study may help lead to reduced use of frequent, unnecessary antibiotic prescribing by doctors as the proliferation of superbugs, resistant to antibiotics, is outpacing the creation of new types of antibiotics.

The study was recently presented at the virtual conference of the World Congress on Gastrointestinal Cancer. The researchers concluded more research is needed concerning the changes in the gut microbiome after being exposed to different antibiotics at different ages and how that may lead to cancer.