Currently, there is no cure for pediatric diffuse brain stem (BS) tumors. Radiotherapy, including proton therapy, is an important component of combination treatment for this cancer, especially in children with a complicated medical history. The article addresses the issues of therapy for pediatric BS tumors and reports the use of proton re-irradiation in a 9-year-old boy with unverified diffuse BS tumor. Proton re-irradiation is an effective treatment option that can sustain and improve the quality of life and prolong survival in children with diffuse BS tumors.

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS) is an aggressive malignant tumor that is mainly found in younger children and is associated with poor prognosis. Our objectives: to present the results of treatment of children with CNS AT/RT under 3 years of age and assess the impact of various prognostic factors on patient survival. The study was approved by the Independent Ethics Committee and the Scientific Council of the N.I. Pirogov Russian National Research Medical University of Ministry of Healthcare of the Russian Federation. The study included 106 patients with CNS AT/RT aged 0–3 years who had been treated and monitored from 2008 to 2020. The median age was 16 (9; 23) months. All the patients underwent primary tumor resection with subsequent chemotherapy according to various protocols. At the time of the analysis, 47 patients (44.4%) were alive, 1 patient (0.9%) was lost to follow-up and 58 patients (54.7%) were dead, of whom 52 patients (90%) had died of disease progression and 6 (10%) – of polychemotherapy complications. One patient developed shunt-related intraabdominal metastasis within 10 months of the diagnosis. The 1-year progression-free survival (PFS) was 0.50; the 2-year PFS was 0.29; the 5-year PFS – 0.27. The median PFS was 12 months. The 1-year overall survival (OS) was 0.72; the 2-year OS was 0.53; the 5-year OS – 0.40. The median OS was 27 months. An analysis of patients with CNS AT/RT under 3 years of age showed that PFS was statistically significantly higher in: children aged > 12 months; children with totally resected tumours; children who had received polychemotherapy in accordance with the ATRT-2006 protocol that included radiotherapy and regional administration of a triplet of chemotherapeutic agents. The OS in patients with CNS AT/RT aged < 3 years was statistically significantly higher in: children aged > 12 months; children who had been treated with radiation therapy; patients who had received cytosar/etoposide intrathecally/intraventricularly; patients who had undergone high-dose chemotherapy with subsequent autologous hematopoietic stem cell transplantation. A multivariate analysis revealed that PFS was influenced by age, tumor location, extent of resection and exposure to radiation therapy, regional chemotherapy or high-dose chemotherapy with autologous hematopoietic stem cell transplantation, while OS was affected by age and exposure to radiation therapy.

High-dose chemotherapy (HDCT) with autologous hemopoietic stem cell transplantation (auto-HSCT) is currently an integral part of a standard of care for younger medulloblastoma (MB) patients and MB patients with relapse. As HDCT regimens are characterized by neurotoxicity, it may add to the one of radiation therapy. Therefore, some patients may develop post-irradiation clinical symptoms and MRI changes characteristic for disease progression, pseudoprogression. We report on a case of a 16-year old patient with relapsed MB treated by standard chemotherapy with consequent HDCT and craniospinal irradiation with a boost to cranial fossa posterior. One month after the radiation therapy was finished she developed focal neurological symptoms. The MRI and PET scan have shown cerebellar changes characteristic for disease progression. However, the therаpy with corticosteroids and bevacizumab was able to resolve most clinical symptoms. The MRI scan have also shown evident positive dynamics. Therefore, the clinical course and imaging dynamics corresponded to pseudoprogression. The probability of pseudoprogression may be higher in patients with MB relapse receiving second irradiation and HDCT with auto-HSCT. As we often do not have a morphological proof of relapse, we have to distinguish between progressive disease and pseudoprogression by a complex of clinical course and imaging data.