Epidemiology of WHO grade 2 and grade 3 gliomas from 2009 to 2021 in Germany

This study provides a comprehensive analysis of the real-world epidemiology of histologically assessed IDH-mutated or IDH-wildtype grade II and III gliomas in Germany between 2009 and 2021, supplemented with a literature-based approach of setting the data in the context of the WHO 2021 classification.

Data from the Centre for Cancer Registry Data (ZfKD) at the Robert Koch-Institute (RKI) was utilized, encompassing all incident cases of histologically (according to the WHO classification of the respective time) newly diagnosed grade II and III gliomas diagnosed between 2009 and 2021, representing a subgroup of the total number of 14,053 glioma cases (including high grade glioma). Data were supplemented with an exploratory literature review on IDH-mutation rates and epidemiology data from the German low-grade glioma (LoG-Glio) disease registry.

The tumor class distribution of newly diagnosed gliomas showed the majority being classified as grade IV glioma and only 9.0% and 9.2% as grade II or III, respectively. The incidence remained stable over the observation period. Literature data indicate mutation rates of IDH of approximately 86% in grade II and 60% in grade III gliomas diagnosed using pre-WHO-2021 criteria. Applying these proportions to 2009-2021 mean incidence cases numbers in an estimate of 459 grade 2 and 328 grade 3 IDH-mutated gliomas (combining astrocytoma and oligodendroglioma) and an incidence rate of 0.6 and 0.5 per 100.000 population for newly diagnosed IDH-mutated gliomas in Germany.

This study gives an overview of the incidence of WHO grade 2 and grade 3 gliomas among the German population. Furthermore, this study highlights the need of molecular information being integrated into epidemiologic monitoring of gliomas to obtain more precise insights into survival and prognostic factors.