Predictors of Acute Radiation Dermatitis and Esophagitis in African American Patients Receiving Whole Breast Radiotherapy.

Abstract

PURPOSE/OBJECTIVE(S)\nAdjuvant whole breast radiotherapy following breast conserving surgery is standard of care in the management of early-stage breast cancer. Two common acute toxicities of breast radiotherapy are esophagitis and dermatitis. African Americans are at higher risk for experiencing treatment-related toxicity and are often under-represented in clinical trials. This study investigates clinical factors associated with increased incidence of Grade 2+ radiation esophagitis (G2RE) and dermatitis (G2RD) in African American breast cancer patients undergoing adjuvant breast radiotherapy.\n\n\nMATERIALS/METHODS\nAn institutional database was developed to include all African American patients with history of breast cancer or DCIS undergoing adjuvant radiotherapy at a single institution from 2013-2019. Records were reviewed to identify patient age, BMI, radiation dose, prone vs supine position, inclusion of boost, and inclusion of regional nodal irradiation (RNI). Radiation treatment plans were reviewed to identify breast size, and volume of breast receiving > 105% and > 107% prescription dose (V105%, V107%). For the subset of patients who received RNI, esophageal dosimetry was reviewed to identify mean/max dose to esophagus (Dmean/Dmax) and volume of esophagus receiving 5 Gy, 15 Gy, 25 Gy, 35 Gy, and 45 Gy (V5 Gy, V15 Gy, V25 Gy, V35 Gy, and V45 Gy). Medical records were reviewed to identify which patients were prescribed silver sulfadiazine or aluminum hydroxide/magnesium hydroxide/simethicone-lidocaine during or immediately following their course of radiotherapy which was used as a surrogate for G2 or higher toxicity.\n\n\nRESULTS\n279 patients were included in the final analysis. 44% of patients were obese and 15% were morbidly obese. 40% of patients received hypofractionated treatment. 36% of patients received RNI. 22% of patients were treated in prone position. On univariable analysis, morbidly obese patients were more likely to develop G2RD (OR 4.05, P < 0.001) and obese patients trended towards a higher incidence of G2RD (OR 1.67, P\u202f=\u202f0.063). On multivariable analysis, increasing breast volume was associated with higher rates of G2RD (OR 3.25, P < 0.001) while hypofractionated radiotherapy was associated with lower rates of G2RD (OR 0.50, P\u202f=\u202f0.027). Patients treated in prone position did trend towards decrease incidence of G2RD (OR 0.46, P\u202f=\u202f0.052). For the subset of patients receiving RNI, 19% of patients experienced G2RE with the best predictor on multivariable analysis being esophagus Dmean (OR 5.56, P\u202f=\u202f0.057).\n\n\nCONCLUSION\nRadiation dermatitis and esophagitis are common toxicities in African American patients undergoing adjuvant breast radiotherapy. Breast size, irrespective of patient s BMI, was associated with worse rate of dermatitis. Prone position and hypofractionated radiation reduced rates of G2RD. RNI was associated with increased rate of G2RE and esophagus Dmean was the best dosimetric parameter correlating with G2RE. These results may be used to help select patients who may be at higher risk for G2 or higher toxicity during radiotherapy.