Initial management of newly diagnosed WHO grade 2-3 adult meningioma following surgery: results from the Dutch Brain Tumour Registry (2016-2021)

Purpose Meningiomas classified as grade 2-3 according to the World Health Organisation (WHO) require combined surgery and in most cases radiotherapy (RT). Their initial management was evaluated using the Dutch Brain Tumour Registry. Methods The study included 393 patients aged >= 18 years with newly diagnosed meningioma WHO grade 2-3 between 2016 and 2021. Factors associated with adjuvant RT < 6 months following surgery were identified using logistic regression analyses, thereby accounting for variation between CNS regional tumour boards through mixed-effect modelling. This variation was further assessed by funnel plots for case-mix adjusted ratios of RT across tumour boards. The association with patients' survival at 5 years was evaluated with inverse probability-weighted accelerated failure (Weibull) models. Analyses were performed on multiple imputed datasets (m = 10) to account for missing data. Results Adjuvant RT was administered to 22.2% (59/266) of patients with WHO grade 2 meningioma following a total resection, to 61.1% (58/95) following a partial resection, and to 68.8% (22/32) of patients with WHO grade 3 meningioma (61.5% after partial and 73.7% after total resection). RT was associated with grade 3, partial resection, bone invasion, and absence of multiple lesions. Management varied across tumour boards for grade 2 meningioma following total resection. Adjuvant RT was associated with survival benefit in case of grade 3 disease (hazard ratio: 0.40, 95%-confidence interval: 0.16-0.95, p = 0.04). Conclusion This national review revealed variation across CNS regional tumour boards in the management of grade 2 meningioma following total resection, and demonstrated survival benefit of adjuvant RT in grade 3 meningioma.