Modern Therapy for Chest Wall Ewing Sarcoma: An Update of the University of Florida Experience.

PURPOSE: Owing to adjacent critical organs, the aggressive multimodality local therapy necessary for Ewing sarcoma of the chest wall is a challenge. Our previous review of historical outcomes at our institution revealed suboptimal disease control and a high incidence of grade ≥3 toxic effects in patients treated before 2006. The purpose of this study was to evaluate changes during the past decade since the introduction of proton therapy. METHODS AND MATERIALS: Thirty-nine consecutive pediatric patients with a chest wall Ewing sarcoma treated between 2006 and 2020 at the University of Florida were identified. The median maximum tumor diameter was 10 cm (range, 4-28 cm). At diagnosis, 19 patients had local disease and the others had a pleural effusion (11), pleural nodules (5), or pulmonary metastases (4). Patients were treated with chemotherapy regimens according to contemporary North American and European protocols: 7 were treated with preoperative, 18 with postoperative, and 14 with definitive radiation. Preceding primary site treatment, 15 patients required hemithorax radiation and 4 patients underwent whole-lung irradiation using photon techniques. The total median radiation dose to the primary tumor was 52.8 GyRBE [relative biological effectiveness] (range, 44.4-55.8 GyRBE). RESULTS: With a median follow-up of 4 years (range, 0.7-14.7 years), the 5-year local control, progression-free survival, and overall survival rates were 97.2%, 74.4%, and 81.6%, respectively, for the whole cohort. For the 19 patients with nonmetastatic disease, the 5-year local control, progression-free survival, and overall survival rates were 100%, 78.9%, and 78.9%, respectively. No patients developed grade ≥4 toxic effects. Two patients (5%) experienced grade 3 toxic effects related to multimodality treatment; both were patients who required surgery to correct scoliosis. Two patients (5%) developed grade 2 pneumonitis. CONCLUSIONS: Compared with our prior published institutional experience, our data suggest improvements in disease control and multimodality toxic effects since the introduction of proton therapy. This should be confirmed with a larger sample size and longer follow-up.