Analysis of safety and efficacy of proton radiotherapy for optic nerve sheath meningioma.

Background: Primary optic nerve sheath meningiomas (ONSMs) represent a group of benign tumors originating from the optic nerve sheath, typically causing painless, gradual onset monocular visual loss, which can result in blindness if left untreated. Radiation therapy represents an important treatment option for patients with ONSM, allowing for preservation and potential improvement in visual function. In particular, proton radiotherapy may enable a reduction of the side effects due to its physical advantage of an inverted dose profile with a steep dose gradient. The study investigates the visual acuity, local tumor control, and treatment-related toxicities following proton beam radiotherapy with a single institutional cohort comprising 32 patients treated for ONSM.
Methods: Patients with primary ONSM, either histologically (16/32) or radiologically confirmed (16/32), which were treated at the Department of Radiation Oncology at the University Hospital Heidelberg (Germany) were assessed in regard to their visual outcomes, treatment toxicity, and local tumor control following radiotherapy according to response assessment in neuro-oncology criteria.
Results: After a median follow-up time of 39.5 months, the 5-year local progression-free survival was estimated at 100%, with 84.4% of patients reporting improvement or stability in visual acuity during their last follow-up. Radiation-induced optic neuropathy (RION) was encountered in 9.4%.
Conclusions: Our study demonstrates proton beam therapy as a safe and effective treatment alternative in the therapeutic management of ONSMs. RION represents a rare but dreaded complication after treatment. Future head-to-head comparisons with photon radiotherapy in a prospective setting are required to demonstrate a potential, additional clinical benefit.
Competing Interests: P.H.S. received honoraria from Novocure for participation in the Advisory Board. A.v.D. has licenses and patents for the VE1 (Roche Ventana) and H09 (Dianova) antibodies, and patent pending for the methylation-based tumor classification. F.S. and A.v.D. are the founders and shareholders of Heidelberg Epignostix GmbH. J.D. received honorary from RaySearch Laboratories, Vision RT Limited, Merck Serono, Siemens Healthcare, PTW-Freiburg Dr. Pychlau, and Accuray Incorporated. S.M.K. is a consultant for Brainlab (Munich), Ulrich Medical (Ulm) and Need Inc. (Santa Monica), and shareholder of Need Inc. (Santa Monica), and received travel funding from Nextim Pic (Helsinki). J.D. is the CEO of the Heidelberg Ion Beam Therapy Center (HIT), and a member of the Board of Directors at the Heidelberg University Hospital.
(© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)