New findings suggest the common recommendation against the use of topical skin treatments during daily radiation therapy may not be warranted, and that unless applied heavily these treatments do not increase the radiation dose to the skin.
Researchers from the Perelman School of Medicine at the University of Pennsylvania (Penn) in Philadelphia published findings in JAMA Oncology (Oct. 18, online ahead of print) from a survey of physicians and patients, as well as a dosimetric and preclinical study.
The survey was designed to evaluate the current common practice advice by physicians regarding topical treatment application prior to radiotherapy.
Of the 105 doctors and nurses who said they regularly manage radiation dermatitis for their patients, 96 of them (91%) reported in the survey that they regularly tell patients not to use skin creams during the hours before radiation treatment. When patients were asked about their doctors’ advice, 111 out of 133 respondents (83%) said they had been told by their healthcare provider to avoid topicals before radiation.
“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 Dr. Brian C. Baumann, in a press release. Dr. Baumann is an adjunct assistant professor of Radiation Oncology at Penn. He is also currently an assistant professor of Radiation Oncology at Washington University in St. Louis.
In order to better understand the actual change in radiation exposure use of topical therapies might cause, the research team used optically stimulated luminescent dosimeters (OSLDs)—a common device for measuring the amount of surface radiation absorbed with each dose. Three squares of paper were used—one uncoated, one treated with a layer of 41% petrolatum, and one with a layer of silver sulfadiazine 1% cream. Each square was placed in the path of a radiation beam (200 monitor units) and the absorbed radiation dose was measured at the surface and at a 2cm depth. They ran the experiment with varying degrees of applied thickness for both topical products. While the surface dose did increase when a very thick layer of the topical agent was applied, researchers found no increase in the surface dose with a moderately thick layer.
“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 said.
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