Presentation (CTI)

OBJECTIVES: Grade 2 IDH-mutant gliomas are rare tumours associated with long survival but progressive disease. Given the rarity of these tumours and the limited availability of treatment approaches, a significant unmet medical need remains. In Portugal and globally, epidemiological data on grade 2 IDH-mutant gliomas are limited. This analysis aims to characterize and estimate the unmet medical need and the epidemiological burden of grade 2 IDH-mutant glioma in Portugal, quantifying the affected patient population.
METHODS: A prevalence-based epidemiological assessment was conducted to estimate the patient population with grade 2 IDH-mutant gliomas in Portugal. Published international epidemiological data and demographic estimates for the Portuguese population (≥12 years) were used. The analysis incorporated prevalence rates for astrocytoma and oligodendroglioma and the proportion of tumours with IDH1/2 mutations. To address gaps in national epidemiological evidence, estimates were reviewed and validated by a Portuguese expert panel involving specialists in neuro-oncology, neurosurgery and medical oncology.
RESULTS: Approximately 90% of astrocytomas and 84% of oligodendrogliomas present IDH1/2 mutations. Considering that 46% of grade 2 glioma patients are managed only with surgery and without immediate need for radiotherapy or chemotherapy, we can estimate a combined prevalence between 2.2-3.9 cases per 100.000 inhabitants. Applying our estimates to the Portuguese population (≥12 years) results in an estimated 211-369 patients with grade 2 IDH-mutant glioma. These numbers were validated by the expert panel, that estimated a mean prevalence of 3.58 cases per 100.000 inhabitants, corresponding to approximately 343 patients nationwide.
CONCLUSIONS: Grade 2 IDH-mutant glioma is a rare disease affecting approximately 211-369 patients in Portugal. The lack of national epidemiological data and disease registries creates important evidence gaps. Expert-validated estimates contribute to a better understanding of the disease and supports healthcare decisions and patient access. The limited treatment options highlight a substantial unmet medical need in this population.