Dosimetric and clinical predictors for radiation esophagitis in patients with breast cancer undergoing conventional fractionated regional nodal irradiation: A prospective study

Abstract This study aimed to determine dosimetric and clinical predictors of radiation esophagitis (RE) in breast cancer patients undergoing conventional fractionated regional nodal irradiation (RNI). Eligible patients received radiotherapy (RT; 50 Gy in 25 fractions) to the chest wall, supraclavicular/infraclavicular fossa, level II axilla, and/or internal mammary chain. RE was graded weekly during RT and at weeks 1, 2 and months 3, 6 post‐RT (CTCAE v3.0). The esophagus was contoured from the lower edge of cricoid cartilage to aortic arch. Esophageal parameters included mean dose (Dmean), maximum dose (Dmax), relative (RV5–RV45) and absolute volumes (AV5–AV45) receiving 5–45 Gy in 5‐Gy increments. Univariate and multivariate analyses identified predictors of grade ≥2 RE. Among 541 prospectively enrolled patients (minimum 6 months follow‐up), 271 (50.1%) had left‐sided breast cancer. Grade 2 RE was 23.7% (128/541), with no grade ≥3 RE. Tumor laterality ( p < .001) was the only clinical risk factor. Esophageal Dmean, Dmax, RV20–RV40, and AV20–AV35 were dosimetric parameters of grade ≥2 RE in univariate analysis. Multivariate analysis identified RV30 <9% (13.9% vs. 31.3%) and AV30 <1 mL (15.2% vs. 30.5%) as optimal dosimetric predictors. Therefore, RE is common in patients receiving RNI, with tumor laterality being the clinical risk factor. Limiting upper esophagus RV30 <9% and AV30 <1 mL may reduce RE risk.