Purpose: Adjuvant whole breast radiation therapy after breast-conserving surgery is the standard of care in the management of early-stage breast cancer. Two of the most common acute toxicities of breast radiation therapy are radiation esophagitis (RE) and radiation dermatitis (RD). African American individuals are at higher risk for experiencing treatment-related toxic effects and are often underrepresented in clinical trials.
Methods and materials: An institutional database was developed to include all African American patients with a history of breast cancer or ductal carcinoma in situ undergoing adjuvant radiation therapy at a single institution from 2013 to 2019. Records were reviewed to identify patient age, body mass index (BMI), radiation dose, prone versus supine position, inclusion of boost, and inclusion of regional nodal irradiation. Radiation treatment plans were reviewed to identify breast size as well as dosimetric parameters to the breast and esophagus. Medical records were reviewed to identify which patients were prescribed Silvadene or Mylanta-lidocaine during or immediately after their course of radiation therapy, which was used as a surrogate for grade 2 (G2) or higher RD or RE, respectively.
Results: A total of 272 patients were included in the final analysis. On univariable analysis, patients with morbid obesity were more likely to develop G2RD, whereas hypofractionated radiation therapy was associated with lower rates of G2RD. On multivariable analysis, greater breast volume was associated with higher rates of G2RD. In the subset of patients receiving regional node irradiation, 19% of the patients experienced G2RE, and the best predictor on multivariable analysis was the mean radiation dose (Dmean) to the esophagus.
Conclusions: Radiation dermatitis and esophagitis are common toxic effects in African American patients undergoing adjuvant breast radiation therapy. In this study, greater breast size, irrespective of the patient's BMI, was associated with a higher rate of dermatitis. Prone positioning during treatment and hypofractionated radiation reduced rates of G2RD. The Dmean to the esophagus was the dosimetric parameter most correlated with G2RE. These results may be used to help select patients at higher risk for toxic effects of G2 or greater during radiation therapy.
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