Primary central nervous system sarcoma with DICER1 mutation-treatment results of a novel molecular entity in pediatric Peruvian patients.

BACKGROUND: A high frequency of primary central nervous system (CNS) sarcomas was observed in Peru. This article describes the clinical characteristics, biological characteristics, and outcome of 70 pediatric patients. METHODS: Data from 70 pediatric patients with primary CNS sarcomas diagnosed between January 2005 and June 2018 were analyzed. DNA methylation profiling from 28 tumors and gene panel sequencing from 27 tumors were available. RESULTS: The median age of the patients was 6 years (range, 2-17.5 years), and 66 of 70 patients had supratentorial tumors. DNA methylation profiling classified 28 of 28 tumors as primary CNS sarcoma, DICER1 mutant. DICER1 mutations were found in 26 of 27 cases, TP53 mutations were found in 22 of 27 cases, and RAS-pathway gene mutations (NF1, KRAS, and NRAS) were found in 19 of 27 tumors, all of which were somatic (germline control available in 19 cases). The estimated incidence in Peru was 0.19 cases per 100,000 children (<18 years old) per year, which is significantly higher than the estimated incidence in Germany (0.007 cases per 100,000 children [<18 years] per year; P < .001). Patients with nonmetastatic disease (n = 46) that were treated with a combination therapy had a 2-year progression-free survival (PFS) rate of 58% (95% CI, 44%-76%) and a 2-year overall survival rate of 71% (95% CI, 57%-87%). PFS was the highest in patients treated with chemotherapy with ifosfamide, carboplatin, and etoposide (ICE) after upfront surgery followed by radiotherapy and ICE (2-year PFS, 79% [59%-100%], n = 18). CONCLUSIONS: Primary CNS sarcoma with DICER1 mutation has an aggressive clinical course. A combination of surgery, chemotherapy, and radiotherapy seems beneficial. An underlying cancer predisposition syndrome explaining the increased incidence in Peruvian patients has not been identified so far. LAY SUMMARY: A high incidence of primary pediatric central nervous system sarcomas in the Peruvian population is described. Using sequencing technologies and DNA methylation profiling, it is confirmed that these tumors molecularly belong to the recently proposed entity "primary central nervous system sarcomas, DICER1 mutant." Unexpectedly, DICER1 mutations as well as all other defining tumor mutations (TP53 mutations and RAS-pathway mutations) were not inherited in all 19 patients where analyzation was possible. These tumors have an aggressive clinical course. Multimodal combination therapy based on surgery, ifosfamide, carboplatin, and etoposide chemotherapy, and local radiotherapy leads to superior outcomes.

Gliomas de alto grado en pacientes pediátricos post - radioterapia: reporte de dos casos en el Instituto Nacional de Enfermedades Neoplásicas, Lima, Perú / High-Grade gliomas in pediatric patients after radiotherapy: A report of two cases at the Instituto Nacional de Ciencias Neurológicas - Lima, Peru

RESUMEN Los gliomas de alto grado inducidos por radioterapia (GIR) son una complicación poco frecuente, pero con un pronóstico ominoso. Poco se sabe sobre la biología subyacente de los gliomas de alto grado post-radiación, aunque algunos estudios sugieren que no hay características histológicas y/o citogenéticas únicas para distinguirlos de los glioblastomas de novo. En el presente artículo, se reportan dos casos pediátricos que reunen criterios para ser considerados GIR y se discute piezas de literatura pertinente. Dos pacientes menores de 10 años sin antecedentes genéticos y clínicos de relevancia fueron diagnosticados en el Instituto Nacional de Enfermedades Neoplásicas de Lima, como portadores de glioma cerebral primario y luego de la aplicación de ciclos de radioterapia, desarrollaron tumores gliales secundarios de alto grado, que fueron validados histopatológicamente en ambos casos. Este reporte enfatiza la necesidad de determinar los factores de riesgo, las vías moleculares de tumorogenesis post- radioterapia y objetivos terapéuticos probables.

SUMMARY Radiation therapy-induced high-degree gliomas (RIGs) are a rare complication with an ominous prognosis. Little is known about the underlying biology of RIGs, although some studies have suggested that there are no unique histologic or cytogenetic features to distinguish them from de novo glioblastomas. Two cases that meet the criteria to be considered RIG are reported, and pertinent pieces of literature are discussed. Two patients under 10 years of age, neither of whom had relevant genetic or clinical history, were diagnosed with primary cerebral gliomas at the National Institute of Neoplastic Diseases in Lima and, after radiation therapy cycles, developed high-degree secondary gliomas, confirmed in both patients by a histopathologic analysis. This report emphasizes the need to identify risk factors, molecular mechanisms of tumor development after radiotherapy, and probable therapeutic targets.