Adult-type diffuse gliomas, central nervous system (CNS) World Health Organization (WHO) grade 4 (CNS WHO grade 4), remain the most aggressive primary malignant brain tumors despite advances in multimodal treatment. We evaluated overall survival and factors associated with mortality among adults with WHO grade 4 diffuse gliomas treated at two tertiary neurosurgical referral centers in the Democratic Republic of the Congo (DRC).

We conducted a multicenter retrospective cohort study including 102 adults with histologically confirmed CNS WHO grade 4 gliomas treated between January 2018 and December 2025. Demographic, clinical, surgical, pathological, treatment, and available molecular characteristics were extracted from institutional records. Overall survival was estimated using the Kaplan–Meier method. Factors associated with mortality were evaluated using multivariable Cox proportional hazards regression adjusted.

Among the 102 patients included, the median age was 50.0 years (interquartile range [IQR], 41.2–57.0), and 64 (62.7%) were male. Gross total resection (GTR) was achieved in 29 patients (28.4%), subtotal resection in 51 (50.0%), and biopsy alone in 22 (21.6%). Postoperative radiotherapy was administered to 65 patients (63.7%), whereas 54 (52.9%) received temozolomide. During follow-up, 88 deaths (86.3%) occurred. Median overall survival was 11.8 months (95% confidence interval [CI], 11.4–12.5). After multivariable adjustment, GTR was independently associated with lower mortality compared with biopsy (adjusted hazard ratio [aHR], 0.22; 95% CI, 0.11–0.44; p < 0.001), while postoperative radiotherapy was associated with a 55% lower hazard of death (aHR, 0.45; 95% CI, 0.28–0.73; p = 0.001). Neither temozolomide administration nor the available molecular biomarkers (PD-L1 expression, Ki-67, MGMT promoter methylation, and IDH1 status) demonstrated independent associations with survival.

In the present study, survival was primarily driven by access to effective surgical and adjuvant treatment. These findings affirm the importance of strengthening access to safe maximal resection, radiotherapy, and coordinated neuro-oncology care, while advocating the need for improving molecular testing and treatment protocols.