New research suggests that just a single course of antibiotics may increase risk for colon cancer, and a full treatment with the drugs may increase it even more.
Taking antibiotics for up to 30 days increases the risk of colon cancer by 8 percent, according to a study published this week in the British Medical Journal.
Antibiotics exposure beyond 30 days can increase the risk by 15 percent, researchers reported.
"The primary message of this study is the importance of antibiotic stewardship: not treating common viral infections with antibiotics, using them for the shortest time period possible, and using targeted antibiotics rather than broad spectrum ones," Cynthia L. Sears, a researcher at the Johns Hopkins Kimmel Cancer Center and study lead author, said in a news release.
For the study, researchers combed through data from the Clinical Practice Research Datalink to look at the effects of antibiotics on nearly 29,000 patients with colon cancer. They compared this to data on more than 137,000 people patients without colon cancer.
To analyze the link between lifestyle and colon cancer, the researchers located patients with contributing factors for the condition, like history of alcohol use, diabetes, obesity and smoking.
About 73 percent of people with colon cancer were likely to have been exposed to antibiotics, along with carrying other risk factors for the condition. That's compared to 69 percent of people who have colon cancer but weren't exposed to antibiotics.
People who were exposed to antibiotics up to 10 years prior had a higher risk of colon cancer than those exposed beyond 10 years.
Conversely, antibiotics exposure longer than 60 days drove down the risk of rectal cancer, according to the researchers.
"This research adds to our understanding that these drugs can have significant off-target effects, including the induction of chronic illnesses," Sears said.