The Prognostic Value of the Treatment and Outcome in Patients with Glioblastoma: A Retrospective Cohort Study

The classification of central nervous system (CNS) tumors by the 2021 World Health Organization (WHO) has led to significant changes in tumor taxonomy. One of the most significant changes is that isocitrate dehydrogenase (IDH) mutant forms of glioblastoma multiforme (GBM) have been differentiated into separate entities, no longer allowing entries to be classified as not otherwise specified (NOS). As a result, this entity only comprises the most aggressive adult-type tumors and established prognostic factors no longer apply. Glioblastoma (GBM) IDH-wildtype CNS WHO grade 4 typically presents necrosis and/or microvascular proliferation and molecular alterations. Herein, we aimed to classify glioblastoma cases to establish a patient survival pattern based on age, gender, the number of masses, tumor location, functional localization, presence of shift, the volume of edema and necrosis, extent of surgery, radiotherapychemotherapy protocol, and isocitrate dehydrogenase (IDH) presence, affecting overall survival were determined retrospectively. A total of 433 patients >20 years old with primary GBM were treated in a single institution between 1996 and 2019. The median survival was 9±0.62 [95% CI 7.78-10.21] months and the survival rate after diagnosis was 39.4% in 1st year, 17% in 2nd year, and 5% in 3rd year. Statistically, age, tumor location, edema, and necrosis were indicated as independent preoperative predictors of prognosis, and younger age at diagnosis, the left temporal and the right occipital location, maximal tumor resection, and administration of temozolomide adjuvant chemotherapy were revealed favorable prognostic factors. Keywords: Glioblastoma, Overall survival, Prognosis, Surgery