Assessing Outcomes of Patients Treated with Re-irradiation Utilizing Proton Pencil-Beam Scanning for Primary or Recurrent Malignancies of the Esophagus and Gastroesophageal Junction

Abstract Background Re-irradiation (re-RT) for locoregionally recurrent esophageal and gastroesophageal junction (GEJ) cancer and de novo esophageal/GEJ cancer arising in-field after a course of prior radiation poses significant treatment challenges given the sensitivity of surrounding organs at risk (OARs). Guidelines for treatment of this presentation are not well-established. Pencil-beam scanning (PBS) proton therapy has the ability to decrease radiation dose to OARs relative to photon plans. We present the first published series to date of re-RT with PBS for esophageal/GEJ malignancies and hypothesize that re-RT with proton PBS will be feasible and improve the safety profile of re-RT for this cohort of patients. Methods Consecutive esophageal/GEJ cancers treated with PBS re-irradiation within a single institution were analyzed. Comparative volumetric-modulated arc therapy (VMAT) photon plans were generated. Seventeen patients were included for analysis. Results At a median follow up of 11.6 months, 1-year local control was 75.3% and overall survival was 68.9%. There were 5 (27.8%) grade ≥ 3 late toxicities. When matched for CTV coverage, proton PBS plans delivered significantly lower doses to the spinal cord, lungs, liver, and heart (all p Conclusions Re-irradiation for de novo or recurrent malignancies of the esophagus/GEJ, when delivered with PBS proton therapy, yields high rates of local control with acceptable acute and late toxicities in a high-risk population and decreased radiation dose to OARs relative to comparative photon plans. This is the largest series of proton re-RT for esophageal malignancies and the first exclusively using PBS.