Researchers have found that acute radiation dermatitis may involve the skin bacterium Staphylococcus aureus and that a simple, low-cost treatment may prevent severe cases in patients undergoing radiation therapy, according to two novel studies published by Kost et al—one a randomized clinical trial and the other a prospective cohort study—in JAMA Oncology. The findings may demonstrate the potential for a new standard of care in this patient population.
Background
Every year, about 10 million patients with cancer are treated with radiation therapy to reduce the size of their tumors. However, acute radiation dermatitis—characterized by red, sore, itchy, or peeling skin—can affect up to 95% of patients receiving this treatment.
Severe cases can cause significant swelling and painful skin ulcers and adversely impact the patients’ quality of life. Nevertheless, little is known about why this condition occurs, and no standardized treatments for preventing severe acute radiation dermatitis have been widely adapted.
”Until now, [acute radiation dermatitis] was assumed to result simply from the skin being burned by the radiation, which meant that not much could be done to prevent it,” explained senior study author Beth N. McLellan, MD, Associate Professor of Dermatology in the Department of Medicine and Chief of the Division of Dermatology at the Albert Einstein College of Medicine as well as Director of Supportive Oncodermatology at the Montefiore Einstein Cancer Center.
S aureus bacteria typically live harmlessly on the skin—often in the nose and armpits—but if the skin is broken by a cut, they are known to cause infections. When courses of radiation therapy—routinely requiring daily treatments over several weeks—weaken the skin’s structure at the treatment site, this can result in infections by allowing S aureus bacteria to break through the skin’s outer layer.
Since S aureus bacteria are implicated in common 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 acute radiation dermatitis. Moist desquamation, the most severe type of acute radiation dermatitis, causes the skin to break down and develop sores.
First Study: Identifying the Source
In the first study, the researchers collected bacterial cultures from 76 patients with cancer before and after treatment with radiation therapy. The cultures were sampled from three different body sites: inside the nose, from skin in the area exposed to radiation, and from skin on the side of the body not exposed to radiation.
Prior to treatment, about 20% of the patients tested positive for S. aureus bacteria but did not have an active infection. Following treatment, the researchers found that 48% of the patients who developed severe acute radiation dermatitis tested positive for the presence of S aureus bacteria compared with only 17% of those who developed the mildest form of the condition. Many patients with the bacteria on their skin also tested positive for nasal S aureus bacteria—suggesting that bacteria from the nose might be infecting the skin.
“This study clearly showed that [S aureus bacteria] play a major role in [acute radiation dermatitis],” stressed Dr. McLellan. “The good news is [that] we have a lot of tools to fight this bacteria,” she added.
Second Study: Preventing Severe Acute Radiation Dermatitis
In the second study, researchers randomly assigned 77 patients—97% (n = 75/77) of whom were undergoing radiation therapy for breast cancer—to receive the experimental antibacterial regimen of the body cleanser chlorhexidine in combination with mupirocin 2% nasal ointment administered twice daily for 5 days, every other week throughout their radiation therapy, or standard-of-care hygiene and moisturizing treatments.
“In [this] study, we tested a topical antibacterial drug combination we thought would be effective and easy for [patients] to use,” Dr. McLellan noted.
Although over 50% of the patients who received the antibacterial regimen developed mild-to-moderate acute radiation dermatitis, none of them developed moist desquamation or experienced adverse effects from the treatment. In contrast, severe acute radiation dermatitis affected 23% of the patients receiving the standard-of-care treatment.
Conclusions
“Our regimen is simple, inexpensive, and easy—so we believe it should be used for [all patients] undergoing radiation therapy, with no need to first test individuals for S aureus. I expect this will completely change protocols for [patients] undergoing radiation therapy for breast cancer,” Dr. McLellan commented.
“Like most of our trials at [the Montefiore Einstein Cancer Center], a majority of our participants were Black and Hispanic members of our community, meaning this protocol is generalizable and effective for [patients] of different races and ethnicities. This is especially important because [those] with darker skin types are more likely to develop severe [acute radiation dermatitis]. The readily available treatment we’ve developed and clinically tested could potentially save hundreds of thousands of [patients] each year in the [United States] from severe [acute radiation dermatitis] and its excruciating side effects,” she concluded.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com and jamanetwork.com.
