Local Control with 21 vs 36 Gy Radiation Therapy of the Primary Tumor Bed for High-Risk Neuroblastoma

Introduction:Local recurrence is a major cause of treatment failure for high-risk neuroblastoma.Radiation therapy (RT) is an important treatment option in pediatric oncology.The aim is to report the outcomes of RT for high-risk neuroblastoma, including local failure (LF), overall survival (OS) and evidence free survival (EFS) in patients treated with total RT dose of 21 and 36 Gy.Methodology: A total of 83 patients were treated from 2012 to 2024, receiving local RT to the primary disease site.Among them were 43 male and 40 female patients with a median age of 3.9 years (from 1.2 to 15.3 years).The total RT dose was 21 Gy for 48 pts (58%), 36 Gy for 35 pts (42%).The target volume was the primary tumor bed, as defined by CT or MRI with a 1 to 1.5 cm margin for the clinical target volume (CTV) and an 0.5 cm margin for the planning target volume (PTV). Results:The median follow-up was 37.7 month (range, 10.3-146.8month), with relapse in 36 out of 83 patients (43%).Recurrent disease in the radiation field occurred in 6 out of 48 patients (12,5%) in the 21Gy arm and in two out of 35 patients (5.7%) in the 36Gy arm.The 3-year EFS was 55.7% 14.4% who received 21 Gy and 48.2%19.1% in the 36Gy arm, while the 3-year OS was 71.8% (9.9%) and 77.2% (10.8%),respectively.Our 3-year LF was 13.5%5.3%for the 21Gy group and 6.7% (4.7%) in the 36Gy arm.