Clinical roles of amplification in diffuse gliomas: a real-world study using the 2021 WHO classification of CNS tumors.

Background: The 2021 World Health Organization Classification of Central Nervous System Tumors updates glioma subtyping and grading system, and incorporates amplification (Amp) as one of diagnostic markers for glioblastoma (GBM).

Purpose: This study aimed to describe the frequency, clinical value and molecular correlation of Amp in diffuse gliomas based on the latest classification.

Methods: We reviewed glioma patients between 2011 and 2022 at our hospital, and included 187 adult glioma patients with available tumor tissue for detection of Amp and other 59 molecular markers of interest. Clinical, radiological and pathological data was analyzed based on the status of Amp in different glioma subtypes.

Results: 163 gliomas were classified as adult-type diffuse gliomas, and the number of astrocytoma, oligodendroglioma and GBM was 41, 46, and 76. Amp was more common in IDH-wildtype diffuse gliomas (66.0%) and GBM (85.5%) than IDH-mutant diffuse gliomas (32.2%) and its subtypes (astrocytoma, 29.3%; oligodendroglioma, 34.8%). Amp did not stratify overall survival (OS) in IDH-mutant diffuse gliomas and astrocytoma, while was significantly associated with poorer OS in IDH-wildtype diffuse gliomas, histologic grade 2 and 3 IDH-wildtype diffuse astrocytic gliomas and GBM.

Conclusion: Our study validated Amp as a diagnostic marker for GBM and still a useful predictor for shortened OS in this group.