Completion of ≥6 cycles of adjuvant temozolomide is the strongest modifiable prognostic factor in glioblastoma: a 17-year real-world cohort of 319 glioma patients from a single Chinese center.

Background: Level-1 evidence supports adjuvant temozolomide (TMZ) after chemoradiotherapy in newly diagnosed glioblastoma, but many patients discontinue before completing the six cycles the regimen calls for-particularly in China, where long-term outcome data anchored to treatment intensity remain scarce. We quantified the independent prognostic value of completing ≥6 cycles of adjuvant TMZ in a 17-year single-center Chinese glioma cohort. Methods: We retrospectively assembled 319 patients with pathologically confirmed glioma treated between 2009 and June 2026 at a tertiary Chinese center; 264 with complete grade, follow-up, resection, and radiotherapy data (tier A) formed the primary cohort. Overall survival (OS) was analyzed by Kaplan-Meier estimation and grade-stratified Cox regression. Robustness of the TMZ ≥6-cycle effect was probed by landmark analyses at 3, 6, 9, and 12 months; inverse-probability-of-treatment weighting (IPTW); restricted mean survival time (RMST); cause-specific Cox regression; prespecified subgroup/interaction analyses; and Results: Median follow-up was 79 months (IQR 42-115); 133 patients (50.4%) died. Five-year OS was 81.8% in WHO I-II, 42.2% in III, and 24.2% in IV (log-rank Conclusion: Completion of ≥6 cycles of adjuvant temozolomide was the strongest modifiable prognostic factor for OS in high-grade glioma, robust across multiple bias-mitigation frameworks, although residual confounding by unmeasured molecular subtype and baseline functional status cannot be fully excluded. Completion-not merely initiation-of adjuvant TMZ warrants explicit tracking as a quality-of-care metric.