High-grade gliomas where resources define survival: a systematic review and meta-analysis of outcomes, surgical access, and molecular diagnostic gaps in low- and middle-income countries

Background High-grade gliomas remain among the most aggressive tumors in neuro-oncology. Although prognosis is strongly influenced by tumor biology, survival in low- and middle-income countries is also shaped by health-system factors, including delayed diagnosis, limited surgical infrastructure, incomplete adjuvant therapy, and restricted molecular diagnostics. The implementation of the 2021 World Health Organization Classification of Central Nervous System Tumors has further exposed diagnostic inequities, as integrated histomolecular classification depends on molecular tools that are not uniformly available in resource-limited settings. Objective This systematic review and meta-analysis aimed to synthesize contemporary evidence on survival outcomes, surgical access, extent of resection, adjuvant treatment delivery, and molecular diagnostic gaps among patients with high-grade gliomas treated in low- and middle-income countries. Methods A systematic search was conducted following PRISMA 2020 recommendations. MEDLINE/PubMed, Embase, Scopus, Web of Science, Cochrane CENTRAL, Global Index Medicus, LILACS, African Index Medicus, IndMED, and Google Scholar were searched for studies published between January 2016 and May 2026. Eligible studies included patients with histologically or molecularly confirmed WHO grade 3 or grade 4 gliomas treated in low- or middle-income countries and reporting survival, surgical-access, adjuvant-treatment, or molecular-diagnostic outcomes. The protocol was registered in PROSPERO as CRD420261398058. Results A total of 30 independent studies met the predefined eligibility criteria and were included in the qualitative synthesis. Twenty-four studies contributed overall survival data, 18 reported surgical-access outcomes, 21 evaluated adjuvant-treatment delivery, and 12 examined molecular-diagnostic availability. Most included investigations were retrospective institutional cohorts, although registry-based studies, randomized clinical trials, and molecular implementation studies were also identified. Survival outcomes varied substantially across healthcare settings and were consistently influenced by delayed diagnosis, limited access to maximal safe resection, incomplete radiotherapy, restricted temozolomide availability, treatment abandonment, and insufficient molecular characterization. Conclusions Survival in high-grade gliomas in low- and middle-income countries is not determined by tumor biology alone. It is shaped by sequential “survival gates”: timely diagnosis, access to maximal safe resection, completion of radiotherapy and temozolomide-based chemotherapy, molecular classification, and longitudinal follow-up. Future strategies should move beyond simple guideline translation and focus on scalable neuro-oncology pathways that improve surgical capacity, adjuvant-treatment continuity, and access to essential molecular diagnostics. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420261398058 , identifier CRD420261398058.