Acute Hematological Toxicity during Cranio-Spinal Proton Therapy in Pediatric Brain Embryonal Tumors

SIMPLE SUMMARY: Embryonal tumors include a heterogeneous group of tumors that need multimodal and multidisciplinary treatments in which craniospinal irradiation (CSI) plays a major role, with a known impact on the acute toxicity and future quality of life of patients. Neutropenia represents one of the most common acute hematological side effects and is responsible for infections and treatment delays that can affect the effectiveness of therapy. To better describe hematological acute toxicity during proton beam radiation treatment, we retrospectively examined 20 subsequent pediatric patients affected by high-risk embryonal tumors subjected to CSI with dual-phase proton therapy after a chemotherapy regimen. Our data suggest that the dual-phase technique is safe and feasible in this setting of pediatric patients with a significant baseline hematological toxicity. Despite all patients having undergone chemotherapy prior to irradiation, no serious hematological toxicity was reported at the end of the treatment with proton therapy, and, therefore, no treatment was discontinued or delayed. ABSTRACT: Background: Embryonal tumors represent a heterogeneous entity of brain tumors that need a multidisciplinary treatment including cranio-spinal irradiation (CSI), with a known impact on the acute toxicity. Proton therapy (PT) boasts a reduction in acute hematological toxicity. Methods: We retrospectively examined 20 pediatric patients affected by high-risk medulloblastoma and other rare embryonal brain tumors subjected to CSI with PT from September 2016 to April 2020. Before CSI, all patients received induction chemotherapy, and three patients additionally received two high-dose courses with thiotepa, followed by an autologous haemopoietic stem cell transplantation. We recorded the total white blood cell count, absolute neutrophil count, platelets, and hemoglobin levels for all patients during PT. Results: Leucocytes and neutrophils decreased directly after the beginning of treatment, reaching a complete recovery at the end of treatment. Hemoglobin values remained constant over the treatment course. The median platelet value decreased until reaching a plateau around halfway through therapy, followed by a slow increase. No cases of febrile neutropenia or severe infections were reported. No treatment discontinuation due to hematological toxicity was necessary. Conclusions: CSI with PT was proven to be safe in this setting of pediatric patients. Our study showed that despite all patients having undergone chemotherapy prior to irradiation, no serious hematological toxicity was reported at the end of the treatment with PT, and, therefore, no treatment was discontinued or delayed.