Outcomes After Proton Therapy for Treatment of Pediatric High-Risk Neuroblastoma

Abstract

Listen

Translate article

Patients with high-risk neuroblastoma (HR-NBL) require radiation to the primary tumor site and sites of persistent metastatic disease. Proton radiation therapy (PRT) may promote organ sparing, but long-term outcomes have not been studied. Sequential patients with HR-NBL received PRT: 2160cGy (relative biological effectiveness) to primary tumor bed and persistent metastatic sites, with 3600cGy (relative biological effectiveness) to gross residual disease. From September 2010 through September 2015, 45 patients with HR-NBL received PRT after systemic therapy, primary tumor resection, and high-dose chemotherapy with stem cell rescue. Median age was 46months at the time of PRT (range, 10months to 12years); 23 patients (51%) were male. Primary tumors were adrenal in 40 (89%); 11 (24%) received boost. Ten metastatic sites in 8 patients were radiated. Double scattered proton beams were used for 19 (42%) patients, in combination with x-rays for 2 (5%). The remaining 26 (58%) received pencil beam scanning, available since January 2013. We observed 97% freedom from primary site recurrence at 3, 4, and 5years. Overall survival rates were 89%, 80%, and 80% and disease-free survival rates were 77%, 70%, and 70%, at 3, 4, and 5years, respectively. With median follow-up of 48.7months from diagnosis (range, 11-90months) for all patients (57.4months for those alive), 37 (82%) patients are alive, and 32 (71%) are without evidence of disease. One patient experienced locoregional recurrence; the remaining 12 (27%) experienced relapse at distant, nonradiated sites. Acute toxicities during treatment were mainly grade 1. No patient has experienced World Health Organization grade 3 or 4 long-term renal or hepatic toxicity. Pencil beam scanning plans required less planning time and resources than double scattered plans. We observe excellent outcomes in patients treated with PRT for HR-NBL from 2010 through 2015, with 82% of patients alive and 97% free of primary site recurrence. No patient has experienced long-term renal or liver toxicity. This treatment maximizes normal tissue preservation and is appropriate for this patient population.