ID #837 Atypical teratoid rhabdoid tumor clinical epidemiological and molecular characterization in a pediatric cohort in Brazil
Larissa Ramos Xavier de Castro, Márcio Ferreira Marcelino, Benicio Oton de Lima, Pedro Henrique Pinto, Renata Lazari Sandoval, Diogenes Diego de Carvalho Bispo, Ricardo Camargo, Milena Reis, Isabella Araújo, Flávio Leão Lima, Estefania Rodrigues Biojone, Flávia Delgado MartinsAbstract
Background
Atypical teratoid/rhabdoid tumor (AT/RT) is a rare and highly aggressive embryonal tumor of the central nervous system (CNS), predominantly affecting infants and young children. Despite advances in molecular diagnostics and multimodal therapy, the prognosis remains poor, particularly in low- and middle-income settings. Objective: To describe the clinical, epidemiological, therapeutic, molecular, and outcome profiles of pediatric patients with AT/RT treated at a tertiary referral center in Brazil.
Methods
This descriptive and analytical study included pediatric patients diagnosed with AT/RT between July 2018 and January 2025. Clinical, radiological, pathological, therapeutic, and outcome data were retrospectively and prospectively collected from medical records. INI1 expression was assessed by immunohistochemistry, and germline genetic testing using next-generation sequencing was performed when available. Overall survival (OS) and event-free survival (EFS) were estimated using the Kaplan–Meier method.
Results
Fifteen patients were included, with a mean age at diagnosis of 22 months. Females accounted for 53% of cases. The most common tumor location was the posterior fossa (61.5%), and 53% of patients presented with metastatic disease at diagnosis. Germline pathogenic variants were identified in three patients, including alterations in SMARCB1, TP53 (Li-Fraumeni syndrome), the R337Hvariant, and SDHB. All patients who received chemotherapy developed significant treatment-related toxicities, predominantly infectious and hematological. Nine patients (60%) died, with a mean survival of approximately four months. Six patients were alive at last follow-up, all of them in complete remission.
Conclusions
AT/RT demonstrated an aggressive clinical course with high rates of metastatic disease, treatment-related toxicity, and mortality. Germline genetic alterations were frequent among tested patients, supporting systematic genetic evaluation. These findings highlight the need for standardized diagnostic pathways, expanded access to molecular profiling, and multicenter collaboration to improve outcomes in pediatric AT/RT.