A retrospective analysis of survival prognostic factors and risk stratification in recurrent glioblastoma

Traditional Cox analysis identifies independent prognostic factors in recurrent glioblastoma (rGBM) but often overlooks their interrelationships. We aimed to develop a predictive nomogram integrating these multifaceted factors to establish a clinically applicable risk stratification model.

In a retrospective analysis of IDH-wildtype rGBM, we used Cox regression to evaluate prognostic factors including age, sex, Ki-67 index, Karnofsky Performance Status (KPS), time to first progression, number of recurrent lesions, tumor location, O⁶-methylguanine-DNA methyltransferase (MGMT) methylation status, and post-recurrence treatment. Significant predictors were used to construct a nomogram in R software, generating a risk stratification model by converting risk scores into categorical levels. The model underwent bootstrap validation.

Our cohort included 206 patients with a median overall survival (OS) of 8.3 (95% CI, 7.2-9.4) months. Multivariate analysis revealed KPS > 50 (p = 0.009; HR 0.61, 95% CI: 0.42-0.88), MGMT methylation (p = 0.033; HR 0.68, 95% CI: 0.48-0.97), time to first recurrence >12 months (p = 0.048; HR 0.69, 95% CI: 0.47-1), single lesion (p = 0.005; HR 0.63, 95% CI: 0.46-0.87), and post-recurrence therapy (surgery: HR 0.35, 95% CI: 0.21-0.59; targeted therapy/Tumor-treating fields (TTF)/re-irradiation: HR 0.5, 95% CI: 0.35-0.71; both p < 0.001) were favorable independent prognostic factors for OS. The nomogram-based risk stratification model successfully stratified patients into low-, medium-, and high-risk groups, yielding distinct OS outcomes (13.9 vs. 6.5 vs. 3.98 months; p < 0.0001). Its predictive performance was confirmed with area under curve (AUC)s of 0.76, 0.72, and 0.73 at 6, 12, and 24 months, respectively.

We developed and internally validated a nomogram-based risk stratification model for rGBM. By integrating key clinical and molecular factors, this tool accurately predicts patient survival.