Investigation of IDH1 in Astrocytoma and Glioblastoma for Reclassification According to 2021 WHO Classification of CNS Tumors

The most prevalent neoplasms of the central nervous system are diffuse gliomas. According to the updated 2021 WHO classification of central nervous system (CNS) tumors, Isocitrate dehydrogenase 1 (IDH1) and IDH2 are now included in the classification of gliomas. IDH1 mutation is responsible for early events in the tumoral transformation by producing the oncometabolite 2-hydroxyglutarate (2-HG). This mutation plays a more significant influence on the outcome of patients. This study is the first one that surveys the relationship between IDH1 and demographic characteristics. Also, we intended to reclassify astrocytoma and glioblastoma multiforme(GBM) for the first time in our center based on the 2021 WHO CNS tumors classification.

During two years of cross-sectional research at Al-Zahra hospital in Isfahan, Iran, IDH1 mutation with immunohistochemistry (IHC) staining was identified in all diagnosed patients with gliomas.

Forty-nine samples were collected whereby, 20 (40.8%) were glioblastoma, and 29 (59.2%) were astrocytomas. Out of the 49 samples, 32 (65.3%) were WHO CNS grade 4 (12 astrocytomas and 20 glioblastomas).  The p-value of 0.019 (less than 0.05) suggests a statistically significant difference between our variables, age, and grade.

We revealed that the most prevalent brain tumor samples were glioblastoma, WHO CNS grade 4, and IDH-wildtype. The majority of the tumors were frontal lobe-based and IHD-negative. The most of the tumors in patients under 40 were astrocytomas (WHO CNS grade 2,3,4) while glioblastoma (WHO CNS grade 4)  was more widespread in those above 55. According to the 2021 WHO CNS tumors classification, glioblastoma IDH-mutant reclassified as astrocytoma, WHO CNS grade 4.