Dental Researchers Get at Root Causes of Cancer Patients’ Mouth Sores

Oral mucositis, a common side effect of chemotherapy, is associated with detrimental changes in the oral microbiome, says new School of Dental Medicine research.

Nurse with a patient undergoing chemotherapy. (Getty Images)

Oral mucositis, a common side effect of chemotherapy, is associated with detrimental changes in the oral microbiome, according to new School of Dental Medicine research. (Getty Images)

For many patients undergoing chemotherapy, the development of mouth sores is a common problem. A team of researchers at UConn School of Dental Medicine are now a step closer to understanding the root causes of these painful mouth ulcers, a condition known as oral mucositis.

Their research, published April 25 in Springer Nature’s Microbiome, represents the most comprehensive study to date about the pathophysiology of oral mucositis in humans due to the effects of chemotherapy. It provides direct evidence that the oral microbiome – a diverse community of microbial organisms that inhabit the mouth – could influence the clinical course of oral mucositis.

Oral mucositis, a common side effect of chemotherapy, is triggered by chemotherapeutic drugs breaking down the mucous membrane lining in the mouth – the oral mucosa. This breakdown induces the painful lesions.

“Oral mucositis due to chemotherapy can impact the delivery of optimal cancer treatment,” said Dr. Patricia Diaz, associate professor in the Department of Oral Health and Diagnostic Sciences, and the study’s lead investigator. “These uncomfortable oral lesions can be associated with clinically significant pain in patients and impact their ability to eat. In extreme cases, a patient’s risk of bloodstream infections is elevated and they are at increased length and cost of hospitalization.”

While this chemotherapy complication has not been widely researched, it has been suggested that the oral microbiome plays a role in inducing the responses that lead to mucositis.

Diaz’s study tracked 49 patients receiving treatment for cancers not located in the mouth during one chemotherapy cycle.

The researchers found that oral mucositis is associated with detrimental changes in the oral microbiome. Patients who developed the most severe oral mucositis lesions showed suppression of beneficial mouth bacteria and outgrowth of harmful ones.

However, it remains unknown if the oral microbiome itself is disrupted during chemotherapy. Further research studies are needed to understand which specific microbiome components are detrimental and in what manner they affect the oral mucosa’s ability to withstand a chemotherapy challenge.

The findings can also shed light on new preventive approaches to stop the lesions from developing. As of now, some evidence exists that an antimicrobial mouth rinse such as chlorhexidine has some benefits in preventing chemotherapy-associated mucositis, but Diaz says more research is needed to develop more effective preventive measures.

“We need to design more targeted preventive strategies aimed at these detrimental microorganisms,” Diaz says. “Since chemotherapeutics are the primary cause of mucosal injury, it is also likely that these microbiome-targeted therapies need to be combined with other treatments to prevent cell death and inflammation at the oral mucosa.”

Study contributors include Takanori Sobue, Amanda K. Dupuy, Angela Thompson, Joseph A. Burleson, Pujan Joshi, Evan Fox, Dong-Guk Shin, Linda D. Strausbaugh, Anna Dongari-Bagtzoglu, and Douglas E. Peterson from UConn. Other contributors include Bo-Young Hong, Linda Choquette, and George M. Weinstock from the Jackson Laboratory for Genomic Medicine; and Andrew L. Salner and Peter K. Schauer from Hartford Healthcare.

The study was supported by the National Institutes of Health, National Institute of Dental and Craniofacial Research (NIDCR).