Real-World Disparities in Molecular Diagnosis of Diffuse Gliomas in Brazil: Insights from LACOG 0619

Background Diffuse gliomas in adults are rare aggressive CNS (central nervous system) tumors whose outcomes are strongly influenced by molecular features. In Brazil, data on epidemiology, molecular diagnostics, and survival are scarce, particularly following the WHO CNS 2021 classification. The LACOG 0619 RWD (Real-World Data) addresses this gap by characterizing Brazilian diffuse glioma patients and evaluating diagnostic disparities. Methods This retrospective, multicenter cohort included adults (≥18 years) with histologically confirmed diffuse gliomas from nine centers in Brazil (2010–2019). Reclassification followed WHO CNS 2021 criteria. Completeness of molecular workup was compared between public and private institutions. Results 828 patients were included (median age 52 years, 56.0% male, 57.6% from private centers). Glioblastoma was the most frequent histology (57%). The central finding was a marked disparity in access to molecular diagnostics: IDH (Isocitrate Dehydrogenase), 1p/19q, MGMT (O6-Methylguanine-DNA Methyltransferase), and NGS (Next-Generation Sequencing) testing were far more frequent in private institutions. Although testing rates improved after 2016, <20% of eligible cases underwent IDH sequencing. Survival differed by histology and WHO 2021 criteria, with five-year OS ranging from 20.2% in IDH-wildtype glioblastoma to 90.9% in IDH-mutant grade 2 gliomas (p < 0.001), confirming the prognostic impact of molecular testing. Conclusions LACOG 0619 is the first and largest RWD to assess molecular diagnostic gaps in diffuse gliomas in Brazil. The study reveals profound inequities between public and private healthcare institutions, underscoring the urgent need to expand equitable access to molecular testing as an essential step toward enhancing patient care and ensuring inclusion in precision oncology.