Grade-Dependent Prognostic Value of Classical Clinicopathological Factors in Glioma: A Single-Center Retrospective Study

Background: The prognostic relevance of classical clinicopathological factors in glioma may vary across World Health Organization (WHO) grades. We examined whether anatomical location, Ki-67, and treatment-related variables show grade-dependent associations with survival. Methods: We retrospectively included 429 patients with glioma treated at a single center between 2012 and 2024. Patients were stratified into WHO grade 2–3 gliomas (n = 129) and WHO grade 4 gliomas (n = 300). Overall survival was evaluated using Kaplan–Meier analysis and Cox proportional hazards models. Additional exploratory analyses were performed in cases with known IDH status with adjustment for IDH and MGMT status. Results: Median overall survival for the full cohort was 29.93 months, and survival differed significantly across WHO grades. In grade 2–3 gliomas, higher Karnofsky Performance Status, non-deep location, and lower Ki-67 were associated with better survival; deep/midline location and Ki-67 ≥ 30% remained independently associated with worse overall survival. Within non-deep grade 2–3 tumors, temporal location was associated with worse survival. In grade 4 gliomas, female sex, non-deep location, and receipt of radiotherapy were independently associated with better survival, whereas Ki-67 was not prognostic. In exploratory molecularly adjusted analyses, deep/midline location remained associated with worse survival across grades, whereas the prognostic effect of Ki-67 became unstable. Longer chemotherapy duration showed a trend toward improved survival in grade 4 gliomas. Conclusions: Classical clinicopathological factors show substantial grade-dependent prognostic heterogeneity in glioma. Anatomical location appears to be a relatively stable adverse prognostic factor across grades, including after partial molecular adjustment. In contrast, the prognostic relevance of Ki-67 was less robust after adjustment for IDH and MGMT and should be interpreted cautiously as an exploratory, molecular-context-dependent marker.