Abstract
BackgroundAs optic nerve sheath meningiomas (ONSM) are rare, there are no prospective studies. Our retrospective analysis focusses on a cohort of patients with uniform disease characteristics all treated with the same radiotherapy regimen. We describe treatment decision making, radiotherapy planning and detailed neuro-ophthalmological outcome of the patients.Methods26 patients with unilateral ONSM extending only to the orbit and the optic canal were evaluated for neuro-ophthalmological outcome. Radiation treatment was planned in a simultaneous integrated boost approach to gross tumor volume (GTV) + 2 mm / 5 mm to 54 Gy / 51 Gy in 1.8 Gy / 1.7 Gy fractions. Follow-up was done by specialized neuro-ophthalmologists. Visual acuity and visual field defects were evaluated after therapy as well as during follow-up.ResultsInterdisciplinary treatment decision for patients with ONSM follows a rather complex decision tree. Radiation treatment planning (equivalent uniform dose (EUD), maximum dose to the optic nerve) improved with experience over time. With this patient selection visual acuity as well as visual field improved significantly at first follow-up after treatment. For visual acuity this also applied to patients with severe defects before treatment. Long term evaluation showed 16 patients with improved visual function, 6 were stable, in 4 patients visual function declined. Interdisciplinary case discussion rated the visual decline as radiation-associated in two patients.ConclusionsWith stringent patient selection radiotherapy for unilateral primary ONSM to 51 Gy / 54 Gy is safe and leads to significantly improved visual function. Interdisciplinary treatment decision and experience of the radiation oncology team play a major role.
Highlights
As optic nerve sheath meningiomas (ONSM) are rare, there are no prospective studies
This single institution retrospective analysis includes all ONSM patients treated with intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost for unilateral optic nerve sheath meningiomas limited to the orbit and optic canal from 2008 to 2017
Patient selection and indication for radiotherapy As ONSM are benign tumors and are sometimes stable in size and symptoms over years, one crucial step in the treatment of these patients is the selection of patients to be treated and the timing of therapy
Summary
As optic nerve sheath meningiomas (ONSM) are rare, there are no prospective studies. Our retrospective analysis focusses on a cohort of patients with uniform disease characteristics all treated with the same radiotherapy regimen. Heterogeneity is based on either primary ONSM confined to the N. opticus and secondary ONSM with spreading of skull base meningiomas into the optic canal [3], different treatment strategies such as Gammaknife radiosurgery and stereotactic fractionated radiotherapy [19] or photon and proton irradiation [20] with different dose and fractionation regimens or are limited to less than 10 patients [21,22,23,24] With all these inconsistencies, local control and functional outcome after high-precision radiotherapy for ONSM seem to be promising and severe side effects and toxicity seem to be rare. Our own experience with 3D-conformal stereotactic radiotherapy showed improvement of visual acuity and a decrease in visual field deficits in approximately 10 and 30% of the patients, respectively [25,26,27]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call