Clinical outcomes of intensity modulated proton therapy and concurrent chemotherapy in esophageal carcinoma: a single institutional experience

Purpose Intensity-modulated proton therapy (IMPT) is an emerging advanced radiation technique. Although dosimetric studies demonstrate the superiority of IMPT for improving target conformity and reducing unnecessary dose to critical normal tissues, clinical experience is limited. We aim to describe our preliminary experience implementing IMPT concurrently with chemotherapy in esophageal carcinoma (EC). Methods and materials From May 2011 through February 2016, 19 patients with EC (median age, 73 years) were treated with IMPT using 180 to 250 MV protons with a median dose of 50.4 Gy relative biological effectiveness in 28 fractions concurrently with chemotherapy. Beam arrangement was most commonly in the posteroanterior and bilateral posterior oblique beams. The Kaplan-Meier method was used to assess survival outcomes. Treatment-related toxicities were evaluated using the Common Terminology Criteria for Adverse Events, version 4.0. Results Single-field and multifield optimization was performed in 13 and 6 patients, respectively. The average gross tumor volume was 69.1 cm³; mean lung and heart dose delivered were 4.94 and 7.86 Gy, respectively; and the maximal spinal cord dose was 32.81 Gy. Clinical complete response was achieved in 84%. Only 4 patients underwent surgery. The most common grade 3 acute toxicities were esophagitis and fatigue (3 patients). Grade 3 esophageal stricture occurred in 1 patient. With a median follow-up time of 17 months, overall survival was 39.2 months, with 1-year overall survival, locoregional recurrence-free survival, and distant metastasis-free survival rates of 100%, 88.8%, and 72.9%, respectively. Locoregional and distant failures occurred in 3 and 5 patients, respectively. Conclusions IMPT is an effective treatment for EC, with high tumor response, good local control, and acceptable acute toxicity.