Research from scientists across the University of South Carolina and several collaborators from the Baylor College of Medicine has found a link between long-term antibiotic exposure and increased progression of colorectal cancer. Led by Dr. Anindya Chanda, assistant professor of environmental health sciences, Dr. James Carson, professor and chair of exercise science, and investigators with the USC Center for Colon Cancer Research, the study was published in Cancer Medicine.
The researchers examined the effects of long-term antibiotic exposure on gut microbiota and found an increase in polyps and tumors in the intestinal tract. These results suggest that the antibiotics eliminated the majority of bacterial flora in the gut.
Prior studies have already established that long-term antibiotic use alters the functional capacity of the gut microbiota, which results in an increased risk of related chronic diseases (e.g., celiac disease, inflammatory bowel disease). Prolonged antibiotic use can also activate the biological mechanisms that initiate or promote colorectal carcinogenesis.
[Photo: Dr. Anindya Chanda]
Photo: Dr. James Carson]
“There are significant gaps in our understanding of how antibiotics increase the risk of colorectal cancer,” says Dr. Chanda. “It is critical that we address this knowledge gap prior to determining clinical recommendations and developing microbial therapies to counter the effects of long-term antibiotic use.”
In addition to linking long-term antibiotic exposure to colorectal cancer, the present study also provides evidence that this exposure can have other implications as well. The disruption of microbiota by even low-dose antibiotic exposures can have long-term metabolic alterations and affect the expression of genes involved in immunity. Other research has shown that these exposures increase the risk of diabetes, which in turn increases the risk of colorectal cancer, and other types of cancer (e.g., lung, prostate, breast, gastric).
“Our results imply that the antibiotics and their effects on intestinal microbiome has a profound impact on the global physical properties and the functioning of the gut,” explains Dr. Chanda. “And this impact determines the severity of the resulting inflammation and cancer.”
In follow-up studies, the researchers plan to investigate the effects of potential “therapeutic microbes” on cancer development and progression. They will also examine how outcomes differ when employing different antibiotics with varied timing relative to polyp development.