Hyperfractionated low-dose (21 Gy) radiotherapy for cranial skeletal metastases in patients with high-risk neuroblastoma.

Abstract

To present a large experience (73 patients) using a standard radiotherapy (RT) protocol to prevent relapse in cranial sites where measurable metastatic neuroblastoma (NB), an adverse prognostic marker, is common. High-risk NB patients with measurable cranial disease at diagnosis or residual cranial disease after induction therapy had those sites irradiated with hyperfractionated 21 Gy; a brain-sparing technique was used for an extensive field. The patients were grouped according to the response to systemic therapy. Thus, when irradiated, Group 1 patients were in complete remission and Group 2 patients had primary refractory disease. Follow-up was from the start of cranial RT. At 3 years, the 39 Group 1 patients had a progression-free survival rate of 51%; control of cranial disease was 79%. Two relapses involved irradiated cranial sites. Two other patients relapsed in the irradiated cranial sites 6 and 12 months after a systemic relapse. At 3 years, the 34 Group 2 patients had a progression-free survival rate of 33%; control of cranial disease was 52%. Group 2 included 19 patients who had residual cranial (with or without extracranial) disease. The cranial sites showed major (n = 13), minor (n = 2), or no response (n = 4) to RT. Five patients had progression in the cranial RT field at 10-27 months. Group 2 also included 15 patients who had persistent NB in extracranial, but not cranial, sites. Of these 15 patients, 2 relapsed in the irradiated cranial sites and elsewhere at 8 and 14 months. Cranial RT was well tolerated, with no Grade 2 or greater toxicity. Hyperfractionated 21-Gy cranial RT might help control NB and is feasible without significant toxicity in children.