Table 6_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.docx

Five-year OS was 81.8% in WHO I–II, 42.2% in III, and 24.2% in IV (log-rank P < 0.0001). The stratified Cox model showed that ≥6 adjuvant TMZ cycles independently halved mortality (adjusted HR 0.46, 95% CI 0.31–0.67, P < 0.001), alongside age ≥60 (HR 1.97, 1.30–2.98) and radiotherapy boost/SIB (HR 1.59, 1.01–2.49). The effect held across all four landmarks (HR 0.44–0.60), after IPTW (HR 0.42, 0.29–0.62), and in the cause-specific model (HR 0.45, 0.31–0.67).

RMST yielded 17.0 additional months at 5 years and 30.3 months at 10 years within WHO IV. In histologic glioblastoma, the pattern was threshold-shaped: 1–5 cycles fared no better than none (HR 0.86, P = 0.62), whereas ≥6 cycles conferred a 64% mortality reduction (HR 0.36, 0.17–0.75). E-values were 3.79 (point estimate) and 2.33 (CI limit nearer the null).</p>Conclusion<p>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.</p>