2693 - Long-Term Outcomes Following Radiation Therapy for Optic Nerve Sheath Meningioma: A Single-Center Experience

08:00am - 09:00am PT

Hall F

Screen: 3

POSTER

Presenter(s)

Tugba Yilmaz, MD - Recep tayyip erdogan Universitesi, Rize, Rize

T. Yilmaz^1,2, M. Marsiglia^3,4, F. Wu^4,5, A. Niemierko^1,4, A. E. Marciscano^1,4, M. R. Bussiere¹, K. S. Oh^1,4, and H. A. Shih^4,6; ¹Department of Radiation Oncology, Mass General Brigham/ Massachusetts General Hospital, Boston, MA, ²Department of Radiation Oncology, Recep Tayyip Erdogan Research and Training Hospital, Rize, Turkey, ³Department of Radiology, Mass General Brigham/ Brigham and Women's Hospital, Boston, MA, ⁴Harvard Medical School, Boston, MA, ⁵Department of Ophthalmology, Mass General Brigham/ Massachusetts Eye and Ear, Boston, MA, ⁶Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA

Purpose/Objective(s):

Optic nerve sheath meningioma (ONSM) accounts for approximately 1-2% of all meningiomas. Treatment of ONSM with radiation therapy (RT) carries potential morbidity, including risk of vision loss. We evaluated our long-term experience of treating ONSM with RT with attention to long-term visual acuity (VA) and other toxicity outcomes.

Materials/Methods:

A single institutional retrospective review was performed identifying all patients with ONSM, treated with RT between January 2004 - January 2024 and at least one year of follow-up. Local tumor control was assessed by imaging (MRI and/or CT) and potential toxicity was assessed by patient reported and objective eye examination data. Radiation-induced optic neuropathy (RION) was defined by any combination of loss of VA, visual field, color vision, optic pathway enhancement on MRI and/or optic disc pallor on fundoscopy.

Results:

A total of 42 patients with either histologically (14) or radiologically (28) confirmed disease were treated with fractionated RT with either protons (32) or photons (10). RT was administered in three different settings: definitive (16; median time between diagnosis to RT initiation was 2 months),salvage after surgery (6; median time between biopsy and RT initiation was 80.5 months), adjuvant after surgery (8; median time between biopsy and RT initiation was 5 months) or following progression while on surveillance (12; median time to RT initiation 44.5 months).The median follow-up was 118 months for patients receiving protons and 65 months for patients receiving photons. 83% of patients were female. The median age at diagnosis was 42 years. Common presenting symptoms were orbital pain, exophthalmos, headache, and diplopia. Duration of symptoms before diagnosis was 6.5 months (range 0- 72 months). Six patients had bilateral tumors and unilateral in the remainder. Median RT dose was 45 Gy (range 45-52.7Gy).Tumor control was 97.6% for the entire cohort and overall survival was 100%. At the first follow up (median of 13 months), VA was stable or improved in 95% of patients. At last follow-up (median of 102 months), stable or improved VA was present in 79.5% of patients. RION was diagnosed in 4 patients at a median time of 29.5 months (range 15- 113 months). Radiation-induced unilateral cataract developed in three patients. All other potentially related long-term toxicities occurred once in the cohort, including persistent eye pain, permanent alopecia, brainstem necrosis, otorrhea, dry eye, seizure, stroke, esotropia and retinal detachment. Further analyses will be presented.

Conclusion:

Patients with ONSM treated with definitive fractionated RT achieve a high local control of tumors with relatively high rate of preserved vision and low rate of optic neuropathy.