Predictors of radiation-induced acute skin toxicity in breast cancer at a single institution: Role of fractionation and treatment volume

Purpose The associations among radiation fractionation, body mass index (BMI), and acute skin toxicity with adjuvant radiation for breast cancer is of increasing interest. This study evaluated the rate of grade ≥2 dermatitis and moist desquamation (MD) in patients with a high BMI who were treated to the breast or chest wall to understand the role of radiation target, fractionation regimen, and BMI. Methods and materials We retrospectively evaluated 280 patients treated with adjuvant radiation for breast cancer after up-front surgery. We collected information on patient demographics, disease and treatment characteristics, and acute skin toxicities. Multiple logistic regression models were used to evaluate for predictors of grade ≥2 dermatitis and MD. Results Patients undergoing post-mastectomy radiation therapy (PMRT) had the highest rate of MD (24%). The rate was lower (8.7%) among lumpectomy patients, but those receiving conventional fractionation had a higher rate of MD (10.9%) compared with hypofractionated therapy (1.8%; P = .05). Among lumpectomy patients, chemotherapy use (odds ratio, 3.74; P = .04) and regional nodal irradiation (odds ratio, 3.29; P = .03) were also significant predictors of MD. Despite an elevated average BMI among lumpectomy patients, hypofractionated therapy resulted in lower rates of skin toxicity. Conclusions We identified multiple risk factors for acute skin toxicity, including the use of PMRT and conventionally fractionated regimens. Elevated BMI, regional nodal irradiation, and chemotherapy use were associated with an increased risk of MD. Our findings highlight the need to explore the use of less toxic hypofractionated regimens in patients who are at the highest risk of acute skin toxicity, including those with a higher BMI and those receiving PMRT.