Can Patients Use Topical Skin Creams During Radiation Therapy?
Contrary to the advice most patients with cancer receive when they go through radiation treatment, topical skin treatments, unless applied very heavily, may not increase the radiation dose to the skin and can be used in moderation before daily radiation treatments, according to findings from a new study. The paper, published by Baumann et al in JAMA Oncology, found that while 91% of clinicians surveyed said they advised patients to avoid these skin treatments and 83% of patients surveyed said they’d received this guidance from their doctors, testing showed there was no difference in the radiation skin dose with or without these creams.
Many patients treated with radiation therapy will experience radiation dermatitis—a rash or burn on the skin. Both prescription and over-the-counter topical treatments are commonly used to give patients relief, some of which—such as silver sulfadiazine cream—contain heavy metals. However, patients have historically been advised to avoid using these treatments in the hours before radiation therapy to avoid increasing the amount of radiation absorbed by the skin.
“This recommendation is a holdover from the early days of radiation therapy, but with the use of modern radiation treatments that can reduce dose to the skin, we hypothesized that it may no longer be relevant,” said the study’s lead author Brian C. Baumann, MD, Adjunct Assistant Professor of Radiation Oncology at the Perelman School of Medicine at the University of Pennsylvania, in a statement. He is also currently Assistant Professor of Radiation Oncology at Washington University in St. Louis.
Survey Phase
For the first part of the study, researchers utilized OncoLink, an online cancer service dedicated to patient and provider education that is run by Penn’s radiation oncology unit. They developed a survey to find out what percentage of providers advise their patients to avoid topical agents just before radiation treatments and what percentage of patients say they received that advice.
Of the 105 doctors and nurses who said they regularly manage radiation dermatitis for their patients, 96 of them (91.4%) said they regularly tell patients not to use skin creams during the hours before radiation treatment. On the patient side, 111 (83.4%) of 133 respondents said they received the advice from their health-care providers.
Dr. Baumann noted that while the survey size is relatively small, “these results suggest the recommendation is still widespread among patients undergoing radiation therapy.”
Measuring Radiation Doses
To address the question of whether these topical agents really do increase the dose of radiation to the skin, researchers used optically stimulated luminescent dosimeters (OSLDs)—a common device for measuring the amount of surface radiation absorbed with each dose. They used three squares of paper: one with nothing on it, one with a layer of a petroleum-based over-the-counter ointment, and one with silver sulfadiazine cream, which is only available by prescription. They placed the squares of paper in the beam’s path and measured the absorbed radiation dose with OSLDs. They ran the experiment with varying degrees of thickness for both products.
Dosimetric measurements showed no difference in the delivered dose at either the surface or a 2-cm depth with or without a 1- to 2-mm application of either topical agent when using en face 6- or 15-MV photons. Surface dose for 6- and 15-MV beams were significantly increased with a thicker (≥ 3 mm) topical application. For 6 MV, the surface dose was 1.05 Gy with a thick layer of petroleum-based ointment and 1.02 Gy for silver sulfadiazine cream vs 0.88 Gy without topical agents; for 15 MV, the doses were 0.70 Gy for a thick layer of petroleum-based ointment and 0.60 Gy for silver sulfadiazine cream vs 0.52 Gy for the controls.
With 6- and 9-MeV electrons, there was a 2% to 5% increase in surface dose with the use of the topical agents. There were no dose differences at the 2-cm depth.
“Based on the results of this study, the use of topical agents just before radiation therapy can be safely liberalized, which may improve quality of life for patients undergoing radiation therapy, but very thick applications of topical agents just before radiation therapy should still be avoided,” Dr. Baumann concluded.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
