Atypical Teratoid Rhabdoid Tumor Across Two Decades: Real-World Outcomes from a Latin-American Institution

AND KEYWORDS Background Atypical teratoid/rhabdoid tumor (ATRT) is a rare, highly aggressive central nervous system tumor of early childhood, with scarce data from Latin America. We describe the clinical features, treatment, and outcomes of pediatric ATRT at a Latin-American tertiary center. Methods Retrospective study of patients <18 years with ATRT treated at the Institute of Pediatric Oncology (IOP/GRAACC/UNIFESP) from 2000 to 2022. Patients <3 years old received high-dose chemotherapy with autologous stem cell transplantation, with or without focal radiotherapy; patients ≥3 years old received conventional chemotherapy and craniospinal radiotherapy. Results Thirty-one patients were included (median age, 1.0 year; range, 0.3–14.4). Among the 24 patients <3 years old, 3-year PFS and OS were 13.8% and 24.6%, respectively. Absence of metastases was associated with higher 3-year PFS (23.7% vs. 0%, p = 0.011) and OS (35.6% vs. 10%, p = 0.021), and metastatic disease remained an independent adverse prognostic factor (HR 3.70; 95% CI 1.11–12.29; p = 0.033). First-line radiotherapy was associated with improved 3-year OS (66.6% vs. 7.8%, p = 0.004); however, in a landmark analysis of the 12 patients who completed first-line treatment, this association was attenuated and non-significant (53.3% vs. 22.2%, p = 0.14). Of the seven patients ≥3 years old (median follow-up, 1.8 years), three were alive at last follow-up. Genetic alterations included SMARCB1, NOTCH1, and KMT2D. Conclusions ATRT outcomes remain poor in this cohort, and metastatic disease independently predicted worse survival. First-line radiotherapy was associated with improved survival in children <3 years, but this was attenuated in the landmark analysis; prospective studies are needed to define its role and timing.