Clinicians no longer need to tell women with breast cancer to stop using an antiperspirant while undergoing daily adjuvant radiation therapy — even when patients favor an "extra-strength" formulation with increased aluminum content, according to researchers.
The first quantitative dosimetric analysis of the effect of aluminum-containing antiperspirants on patients undergoing breast radiation therapy shows there is no significant difference in surface dose or increase in skin toxicity regardless of aluminum concentration or gantry angle of the tangent beams, say Brian C. Baumann, MD, of the Perelman School of Medicine at the University of Pennsylvania, in Philadelphia, and colleagues.
"Our quantitative dosimetric analysis reinforces the conclusions of the toxicity studies that antiperspirant use is acceptable during breast radiation," the study authors say in a report published online July 24 in Radiotherapy and Oncology.
The study's online, anonymous international survey of clinicians also reveals that despite the lack of scientific evidence, 82% of clinicians routinely tell their breast cancer patients not to use antiperspirants while undergoing radiation therapy (P = .059). In the survey, 71% said they made the recommendation because they were concerned about electron scatter from metals, 63% said they were concerned about bolus effect, and 55% said it was just "routine clinical practice."
In the study's parallel online survey of patients, 79% said they had been warned not to use an antiperspirant during radiation therapy. More than 90% of people in the United States use an antiperspirant as part of their regular personal hygiene, the study authors note.
"While the sample size of the survey is relatively small, the percentage of patients who received the advice to avoid antiperspirants and the percentage of providers who routinely offer this advice were very similar," Dr Baumann, who is assistant professor of radiation oncology at Washington University in St. Louis, in Missouri, said in a statement. "We cannot make any conclusions about the exact prevalence of this recommendation, but we think the results strongly suggest that the recommendation remains popular."
Clinicians may be reluctant to let go of the no-antiperspirant recommendation because previous trials did not quantify axillary erythema using photoanalysis, and the only other dosimetric study of antiperspirant effect on surface dose was published 20 years ago, the authors state.
"In our opinion, there are shortcomings in the available studies on axillary antiperspirant use during breast radiation that may have inhibited providers from liberalizing antiperspirant use," Dr Baumann told Medscape Medical News. "Based on the results of this study and the prior randomized controlled trials that have investigated this question, we think that the evidence strongly suggests that women can liberalize their use of antiperspirants during breast radiation therapy without an increased risk of radiation dermatitis."
Not wearing an antiperspirant during daily radiation therapy that lasts from 3 to 6 weeks can have have a significant negative impact on the personal and professional lives of patients. An earlier survey showed that 79% of breast cancer patients who underwent weeks of radiation therapy were quite worried about body odor, the study authors note.
Dr Baumann said he learned from several of his own patients how uncomfortable and embarrassed they were by not being able to wear deodorant. "It was those stories that inspired me to pursue this research question," said Dr Baumann, who now advises his patients to continue their normal use of antiperspirants. "I think it is always good practice for physicians to better understand the consequences of a given recommendation they offer to patients."
For the study, the investigators measured surface dose in a tissue-equivalent phantom using optically stimulated luminescent dosimeters (OSLDs) with and without two commercially available antiperspirants. The standard deodorant used in the study contained 15% aluminum zirconium tetrachlorohydrex glycine; the extra-strength version contained 25% of the same compound.
The roll-on antiperspirant was applied in eight layers — a much thicker application than used by patients, the investigators point out — prior to radiation therapy with 6 MV photons delivered 200 MU at 100 cm SSD at 0, 30, 60, and 90 sequential gantry angles using a TrueBeam linear accelerator. The OSLDs were replaced after each fraction and processed according to standard protocol.
"We tested not only the surface dose of en face beams as in the [previous dosimetric] 1997 study but also assessed surface dose at multiple gantry angles, since patients receiving breast radiation are treated with tangent fields," Dr Baumann explained. "Even in the extreme case of extra-strength antiperspirant copiously applied just prior to radiation, we found no difference in the surface dose related to antiperspirant use."
OSLD measurements demonstrated that there was no difference in surface dose at gantry angles of 0º, 30º, 60º, and 90º when antiperspirants were used and when they were not used. Even for a beam angle of 60º, the largest absolute difference of 7 cGy (5%) was within the OSLD margin of error.
There were 133 patients who participated in the online survey. Of these, 92 underwent adjuvant radiation therapy for breast cancer. There were no significant differences in patient responses about antiperspirant recommendations regardless of whether radiation dermatitis was being managed by a physician or a nurse. In addition, patient responses were not significantly different with respect to the age, education level, or ethnicity of the patients, nor was there a significant difference in the length of time that had elapsed since completion of breast radiation therapy (P > .05).
The survey also showed that 53 of the 92 patients with breast cancer reported moderate or severe skin erythema following radiation therapy, even though the vast majority had been advised to avoid antiperspirants.
Of the 108 healthcare providers surveyed, half were radiation oncologists, and half were radiation oncology nurses. Of the physicians working in an academic setting, 93% recommended that antiperspirant use be avoided. Of physicians in private practice, 72% recommended that antiperspirants be avoided. There was no significant difference in responses between physicians and nurses (P > 0.05).
More recently, Dr Baumann and colleagues have been investigating whether the recommendation to avoid lotions for several hours before undergoing daily radiation therapy may be irrelevant too.
Early findings using both dosimetric analysis and animal models suggest that thin or moderately applied creams, even if applied just prior to radiation therapy, have minimal impact on skin dose regardless of beam energy or beam incidence. However, the application of very thick amounts of cream just prior to radiation therapy increased surface dose and should be avoided, Dr Baumann said.
No funding for the study has been disclosed. The authors have disclosed no relevant financial relationships.
Radiother Oncol. Published online on July 24, 2017. Abstract