CHICAGO, Oct. 18 (Xinhua) -- Applications of creams or ointments in the 1-2 mm range are safe for cancer patients undergoing radiation therapy and won't increase the radiation dose too much to cause concern, according to a new study from Washington University School of Medicine in St. Louis and the Perelman School of Medicine at the University of Pennsylvania.
The researchers surveyed patients and radiation oncologists to determine whether it is still common for patients to be advised to avoid topical skin therapies before they undergo radiation therapy. According to surveys of 133 patients and 108 doctors, more than 83 percent of patients received this message, and 91 percent of doctors reported giving that advice.
The study included patients with several cancer types. About 87 percent of the patients surveyed had been diagnosed with breast cancer, while other patients had diagnoses of different tumors, including head and neck, lung and anal cancers.
The researchers measured the radiation dose at the surface of a material similar to human tissue that was covered with topical agents of differing applied thicknesses. Only with the applications of 3 mm or greater in thickness did the radiation dose significantly increase.
They also measured doses in mice. The researchers found no additional DNA damage or cell death in the skin of mice that were irradiated in the presence or absence of creams of varying thicknesses.
The researchers studied an over-the-counter petroleum-based ointment named Aquaphor that often is recommended to radiation therapy patients, as well as a prescription-only product called silver sulfadiazine cream.
"Most patients undergoing radiation therapy are treated daily for many weeks," said first author Brian C. Baumann, a Washington University assistant professor of radiation oncology.
Most will develop at least a mild skin reaction caused by the radiation, with some patients experiencing significant redness and irritation, not unlike a sunburn. Patients frequently use topical agents to ameliorate this condition. Contrary to popular belief, the results of this research suggest that topical creams and ointments can be safely applied before radiotherapy. However, patients should avoid applying a very thick layer just before radiotherapy.
The study was published Thursday in JAMA Oncology.
