Background. Intensive multimodal treatment can improve survival in patients with high-risk neuroblastoma, and consolidative radiation therapy has contributed to local control. We examined the clinical outcomes of patients who underwent consolidative radiation therapy at our institution.

Methods. We retrospectively reviewed the records of patients with high-risk neuroblastoma who underwent consolidative radiation therapy from March 2001 to March 2021 at Asan Medical Center. Patients underwent multimodal treatment including high-dose chemotherapy, surgery, stem cell transplantation, and maintenance therapy. Radiation (median, 21.0 Gy; range, 14–36) was administered to the primary site and surrounding lymph nodes.

Results. This study included 37 patients, and the median age at diagnosis was 2.8 years (range, 1.3–10.0). Four patients exhibited local failure, and 5-year free-from locoregional failure rate was 88.7%, with a median follow-up period of 5.7 years. The 5-year disease-free survival (DFS) and overall survival (OS) rates were 59.1% and 83.6%, respectively. Univariate analysis revealed that patients with neuron-specific enolase levels >100 ng/mL had significantly worse DFS and OS (P = 0.036, 0.048), and patients with no residual disease before radiation therapy showed superior OS (P = 0.029). Furthermore, patients with 11q deletion or 17q gain exhibited poor DFS and OS, respectively (P = 0.021, 0.011). Six patients experienced grade 1 acute toxicity. Late toxicity was confirmed in children with long-term survival, predominantly hypothyroidism and hypogonadism, typically < grade 3, possibly attributed to combination treatment. Four patients experienced late toxicity ≥ grade 3 with chronic kidney disease, growth hormone abnormality, ileus, premature epiphyseal closure, and secondary tumor, and recovered by hospitalization or surgical treatment.

Conclusions. In patients with high-risk neuroblastoma, consolidative radiotherapy to the primary tumor site resulted in excellent local control and a tolerable safety profile.

Keywords: neuroblastoma, radiation therapy, combined modality therapy, treatment outcome, toxicity