Dose-Volume Predictors for Radiation Esophagitis in Patients With Breast Cancer Undergoing Hypofractionated Regional Nodal Radiation Therapy.

ABSTRACT

PURPOSE: Our objective was to assess the incidence and dose-volume predictors of radiation esophagitis (RE) in patients with breast cancer undergoing hypofractionated regional nodal irradiation. METHODS AND MATERIALS Eligible patients who received intensity modulated radiation therapy (RT) at the chest wall, the supraclavicular/infraclavicular fossa, level II axilla, and/or the internal mammary chain after mastectomy were included. The prescribed dose was 43.5 Gy in 15 fractions. RE was evaluated weekly during RT and at 1 and 2 weeks, followed by 3 and 6 months after RT, and was graded according to National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. The esophagus was contoured from the lower border level of the cricoid cartilage to the lower margin of the aortic arch. Esophageal total volume, mean dose, maximum dose, and the relative volumes (RV) and absolute volumes (AV) receiving at least 5 to 45 Gy by 5-Gy increments (RV5-RV45 and AV5-AV45) were evaluated. Univariable and multivariable logistic regression analyses were performed to determine risk factors for RE, and receiver operating characteristic curves were obtained to identify the thresholds of esophageal dosimetric parameters. RESULTS: In total, 298 patients were included between May 8, 2020, and January 5, 2022 (minimum post-RT follow-up 6 months). Grade 2 and 3 RE incidence was 40.9% (122/298) and 0.3% (1/298), respectively. No grade 4 or 5 RE was observed. Esophageal RV20-RV40 and AV35-AV40 were significantly associated with the risk of grade ≥2 RE after adjusting for tumor laterality and internal mammary nodal irradiation. RV25 and AV35 were optimum dose-volume predictors for grade ≥2 RE at thresholds 20% for RV25 (35.9% vs 60.9%; P = .04) and 0.27 mL for AV35 (31.0% vs 54.6%; P = .04). CONCLUSIONS: RE is common in patients with breast cancer undergoing hypofractionated regional nodal irradiation. Maintaining the upper esophageal V25 at <20% and V35 at <0.27 mL may decrease the risk of RE.