Abstract
BackgroundMeningiomas of the skull base account for 25–30% of all meningiomas. Due to the complex structure of the cranial base and its close proximity to critical structures, surgery is often associated with substantial morbidity. Treatment options include observation, aggressive surgical intervention, stereotactic or conventional radiotherapy.In this analysis we evaluate the outcome of 110 patients with meningiomas of the skull base treated with particle therapy. It was performed within the framework of the “clinical research group heavy ion therapy” and supported by the German Research Council (DFG, KFO 214).MethodsBetween May 2010 and November 2014, 110 Patients with skull base meningioma were treated with particle radiotherapy at the Heidelberg Ion Therapy Center (HIT). Primary localizations included the sphenoid wing (n = 42), petroclival region (n = 23), cavernous sinus (n = 4), sella (n = 10) and olfactory nerve (n = 4). Sixty meningiomas were benign (WHO °I); whereas 8 were high-risk (WHO °II (n = 7) and °III (n = 1)). In 42 cases histology was not examined, since no surgery was performed.Proton (n = 104) or carbon ion (n = 6) radiotherapy was applied at Heidelberg Ion Therapy Center (HIT) using raster-scanning technique for active beam delivery. Fifty one patients (46.4%) received radiotherapy due to tumor progression, 17 (15.5%) after surgical resection and 42 (38.2%) as primary treatment.ResultsMedian follow-up in this analysis was 46,8 months (95% CI 39,9–53,7; Q1-Q3 34,3–61,7). Particle radiotherapy could be performed safely without toxicity-related interruptions. No grade IV or V toxicities according to CTCAE v4.0 were observed. Particle RT offered excellent overall local control rates with 100% progression-free survival (PFS) after 36 months and 96.6% after 60 months. Median PFS was not reached due to the small number of events. Histology significantly impacted PFS with superior PFS after 5 years for low-risk tumors (96.6% vs. 75.0%, p = 0,02). Overall survival was 96.2% after 60 months and 92.0% after 72 months from therapy. Of six documented deaths, five were definitely not and the sixth probably not meningioma-related.ConclusionParticle radiotherapy is an excellent treatment option for patients with meningiomas of the skull base and can lead to long-term tumor control with minimal side effects. Other prospective studies with longer follow-up will be necessary to further confirm the role of particle radiotherapy in skull base meningioma.
Highlights
Meningiomas of the skull base account for 25–30% of all meningiomas
Local tumor control and survival The reverse Kaplan-Meier estimate for median followup was 46,8 months for progression-free survival and 57,97 month for overall survival
Histology significantly impacted progression-free survival (PFS) with inferior PFS at 60 months (75.0% for high-risk vs. 96.6% for low-risk histology, p = 0,02) (Fig. 2), notably there were only eight patients and one event in the high-risk group, adding to the fact that histology at primary diagnosis was unknown for 38.2% of the patients and limiting the conclusions to be drawn on this data regarding the impact of histology
Summary
Due to the complex structure of the cranial base and its close proximity to critical structures, surgery is often associated with substantial morbidity. Aggressive surgical intervention, stereotactic or conventional radiotherapy. In this analysis we evaluate the outcome of 110 patients with meningiomas of the skull base treated with particle therapy. Many analyses focus on meningiomas of the skull base because of its intricate anatomy and the close proximity to vascular structures, cranial nerves and the brainstem; treatment in those cases is challenging and treatment options are controversially discussed. Due to the complex anatomy of the skull base, tumor adherence to bony structures and the close proximity to sensitive organs at risk (OAR), total resection is often not possible as it may cause to substantial morbidity. Additional radiotherapy can improve chances for longterm tumor control [7]
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