Management approaches in WHO Grade III Meningioma: a National Oncology Trainees’ Collaborative for Healthcare Research (NOTCH) UK multi-centre retrospective study

Background WHO Grade 3 (G3) meningiomas are rare tumours with limited data to guide management. This retrospective study documents UK management approaches across 14 centres over 11 years. Methods Patients with WHO G3 meningioma between 01/01/2008 and 31/12/2018 were identified. Data was collected on demographics, management strategy, adjuvant radiotherapy, approach in recurrence setting and survival. Results 84 patients were identified. 21.4% transformed from lower grade disease. 96.4% underwent primary surgical resection, with 20.8% having evidence of residual disease on their post-op MRI. 59.3% of patients underwent adjuvant radiotherapy (RT) following surgical resection.Overall median PFS and OS was 12.6 months and 28.2 months respectively. Median OS in the group who underwent complete surgical resection was 34.9 months, compared to 27.5 months for those who had incomplete resection (HR 0.58, 95% CI 0.27-1.23, p=0.15). Median OS was 33.1 months for those who underwent adjuvant RT and 14.0 months for those who did not (HR 0.48, 95% CI 0.27-0.84, p=0.004). Median adjuvant RT dose delivered was 60Gy (range 12Gy-60Gy), 45.8% of adjuvant RT was delivered using IMRT.At disease relapse, 31% underwent salvage surgery and 29.3% underwent salvage RT. Of those treated with salvage RT, 64.7% were re-treats and all were treated with hypofractionated RT. Conclusions Surgery continues to be the preferred primary management strategy. Post-operative MRI within 48 hours is indicated to assess presence of residual disease and guide further surgical options. Adjuvant radiotherapy plays an important part of the management paradigm in these patients with the data supporting an attached survival advantage. Further surgery and re-irradiation is an option in the disease recurrence setting with radiosurgery frequently utilised in this context.