Correlation Between 1p19q Status and Various Biomarkers in Selected Central Nervous System Tumors

Background and objective: H mutations and 1p19q co-deletion are the main biomarkers used in the nomenclature of glial tumors. Detection of 1p19q co-deletion directly diagnoses oligodendroglioma. The primary objective of this study was to evaluate the 1p19q co-deletion status in diffuse gliomas in accordance with the World Health Organization (WHO) integrated classification framework. In addition, we aimed to investigate the presence of 1p19q alterations in other, less frequently encountered glial-derived central nervous system tumors. Methods: We retrospectively analyzed the biomarker findings obtained from the pathology preparations of 167 cases of glial brain tumors (93M, 74F) operated in the Department of Neurosurgery at Yeditepe University Hospital and whose preparations were investigated in the pathology laboratory between 2019 and 2021. The data was statistically analyzed. Results: ATRX, IDH1, EGFR, GFAP, and OLIG2 positivity were associated with the positivity of 1p19q co-deletion. Our study showed that only 4% of tumors with no O6-methylguanine-DNA methyltransferase (MGMT) methylation showed 1p19q co-deletion positivity. Tumors with low (0-20%) and moderate (21-60%) levels of MGMT methylation showed higher rates of 1p19q co-deletion positivity. However, tumors with high (81-99%) and complete (100%) MGMT methylation had lower rates of 1p19q co-deletion positivity. Conclusions: The detection of 1p19q co-deletion in other tumors and its peculiar relationship with MGMT methylation made us think of the complexity of tumor biology and how both genetic and epigenetic factors interplay to influence tumor behavior and response to therapy.