Researchers from Johns Hopkins University School of Medicine recently conducted a study that appears to suggest that antibiotics may increase a person’s risk for cancer. The aim of the study, recently published online in the journal Gut, was to determine the association between oral antibiotic use and colon cancers. They found that taking certain antibiotics may raise the risk of developing colon cancer, especially when taken multiple times or for long courses.
For the study, the researchers examined the health records of over 166,000 middle-aged and older primary care patients, ages 40-90, from the United Kingdom whose information was collected between 1989 and 2012. Nearly 30,000 of the participants were diagnosed with colon or rectal cancer at some point. The others were used for comparison. The adults were followed for about eight years.
Information about the subjects’ antibiotic use was gathered and split into categories based on drug classes. Any antibiotic prescription patients received from the time they enrolled in the study until a year before a colon cancer diagnosis was reviewed. The amount of time patients used antibiotics was also examined.
The results of the analysis showed that patients who’d received a prescription for antibiotics had a slightly higher risk of colon cancer versus those with no prescription. Participants that had been on antibiotics for a total of two weeks had a risk that was 9 percent higher, while those who were on the medications for more than 60 days total had a 17 percent higher risk. Penicillins were associated with an increased risk of colon cancer in the first and middle parts of the colon, while tetracyclines were associated with a reduced risk of rectum cancer in the last part of the bowel.
The researchers note that there were limitations to their study. For example, they had no information on people’s diet and exercise habits, which are factors that are known to affect colon cancer risk. They were able to factor in some known risk factors for colon cancer, including obesity, diabetes, and smoking. The team did not establish cause and effect.