Mass General Brigham/Massachusetts General Hospital/Harvard Med School Boston, MA
M. Bakhtiar1, J. Y. Wo2, H. J. Roberts2, A. R. Parikh3, S. J. Klempner3, J. W. Clark3, M. R. Strickland3, C. R. Morse4, A. Niemierko5, and T. S. Hong2; 1Harvard Radiation Oncology Program, Boston, MA, 2Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 3Division of Medical Oncology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 4Division of Thoracic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 5Massachusetts General Hospital, Boston, MA
Purpose/Objective(s): Re-irradiation for esophageal cancer carries a risk of toxicity. Proton radiotherapy may result in acceptable toxicity due to nearby tissue sparing. This study describes patients who received proton re-irradiation (PRT) for esophageal cancer at our institution between 2015 and 2023.Materials/
Methods: We conducted a single-institution retrospective review of patients who received PRT for esophageal cancer. Medical records were reviewed for patient and disease characteristics, treatment details, and acute toxicities according to the common terminology criteria for adverse events (CTCAE) v5.0. Long-term toxicities (>3 months post-treatment) including major adverse cardiac events (MACE) and vertebral fractures were documented. Descriptive statistics were calculated. Kaplan-Meier survival analysis was performed. Results: Fifteen patients were included in the study. Median age was 65.0 (inter-quartile range [IQR]: 60.0-74.0); 47% (n=7) were female. Common reasons for prior thoracic radiotherapy (RT) included esophageal cancer (n=6, 40%) and Hodgkin’s Lymphoma (n=5, 33%). Median prior dose was 41.2Gy (IQR: 36.0-50.4) in median 25 fractions. Median time since prior RT was 10.0 years (IQR: 5.2-28.2).Patients had squamous cell carcinoma (n=9, 60%) or adenocarcinoma (n=6, 40%). Eight patients had endoscopic staging; the most common tumor and nodal stages were T3 (n=5) and N1 (n=4).Patients received passive scatter (n=10) or pencil beam scanning technique (n=5). All received 50.4Gy in 28 fractions. Six patients (40%) received chemotherapy before RT; 13 (87%) received it concurrently, most commonly carbo/paclitaxel (n=10, 75%). All patients completed treatment without interruption. The most common acute toxicities were fatigue (n=8, 53%), dysphagia (n=8, 53%), and anorexia (n=4, 27%). Two patients (13%) experienced grade 3 dysphagia; all other acute toxicities were grade 1-2.Six patients (40%) had esophagogastric surgery. All had an R0 resection, and 3 (20%) had a pathologic complete response.One patient had a post-RT vertebral fracture. Five patients (33%) developed a MACE, including cardiac arrest (n=3), myocardial infarction (n=1), and heart-failure related hospitalization (n=1). Among patients who developed a MACE, median mean heart dose was 8.2Gy (IQR: 4.6-9.4); for the entire cohort it was 4.2Gy (IQR: 3.2-8.2). Three patients who developed a MACE had a pre-existing cardiac comorbidity, such as coronary heart disease.Median follow-up was 2.2 years (IQR: 1.1-6.3). Two-year survival was 79% (95% CI: 48-93%). Two patients (13%) had disease recurrence, one local and one distant. Conclusion: In this single-institution series, patients who received PRT for esophageal cancer experienced low-grade acute toxicities and good disease control. One-third developed a MACE. Patients who underwent esophagogastric surgery demonstrated excellent treatment response. Our institutional experience may inform selection of patients for PRT for esophageal cancer.
