Study explains how antibacterial treatment helps in skin problem caused by radiation therapy

New York [US], May 7: If you are fed up with skin problems caused by radiation therapy, then there’s some good news for you.

A common skin bacterium is implicated in many acute radiation dermatitis (ARD) cases, and researchers at the Montefiore Einstein Cancer Centre (MECC) have shown that a straightforward, affordable treatment can avoid severe instances, potentially establishing a new standard of care for those receiving radiation therapy. Two publications that were published in JAMA Oncology detailed their findings. Radiation therapy is used to treat 10 million patients annually to shrink their tumours. 

“Until now, ARD was assumed to result simply from the skin being burned by the radiation, which meant that not much could be done to prevent it,” said Beth N. McLellan, M.D. director, supportive oncodermatology at Montefiore Einstein Cancer Center, chief of the division of dermatology at Montefiore Health System and Albert Einstein College of Medicine, and senior author of the two studies.

“The readily available treatment we’ve developed and clinically tested could potentially save hundreds of thousands of people each year in the U.S. from severe ARD and its excruciating side effects.”Staphylococcus aureus (SA) bacteria, often shortened to “staph,” typically live harmlessly on the skin, often in the nose and armpits. But, they can cause infections if the skin is broken by a cut. Radiation weakens the skin’s structure at the treatment site and can result in infection by allowing SA to break through the skin’s outer layer. Courses of radiation therapy–routinely requiring daily treatments over several weeks–increase the risk for skin infection to occur.

Since SA is implicated in common skin disorders that lead to a breakdown in the skin such as eczema, Dr. McLellan and her colleagues reasoned that the bacteria might also play a role in ARD. In one of the JAMA Oncology studies, the MECC researchers enrolled 76 patients undergoing radiation therapy for cancer. Bacterial cultures were collected from patients before and after radiation treatment, from three different body sites: inside the nose, from skin in the radiated area, and from skin on the side of the body not exposed to radiation.

Before treatment, approximately 20% of patients tested positive for SA but did not have an active infection. Following treatment, 48% of those patients who developed severe ARD tested positive for the presence of SA, compared with only 17% of patients who developed the mildest form of the condition. Many patients with SA on their skin also tested positive for nasal SA, suggesting that SA from the nose might be infecting the skin.”

“This study clearly showed that SA plays a major role in ARD,” said Dr. McLellan. “The good news is we have a lot of tools to fight this bacteria. In a second study, we tested a topical antibacterial drug combination we thought would be effective and easy for people to use.”The second study enrolled 77 patients undergoing radiation therapy, all but two of whom had breast cancer. Participants were randomized to receive either the standard of care at MECC (normal hygiene and moisturizing treatment such as Aquaphor), or the experimental antibacterial regimen. This treatment involved using the body cleanser chlorhexidine along with mupirocin 2% nasal ointment twice a day for five days, every other week, throughout their radiation treatment.