Efficacy and Safety of Proton Beam Therapy for Primary Optic Nerve Sheath Meningioma

Abstract

Purpose Management of optic nerve sheath meningiomas (ONSM) remains challenging. Photon radiation therapy (PhRT) is the most common treatment for sight-threatening ONSM. Proton beam therapy (PBT) is less commonly used because it is more expensive and because there are questions about its efficacy specifically in relation to ONSM. PBT has the theoretical advantage of reducing radiation exposure to adjacent structures. We report the visual outcome of patients with primary ONSM managed at the Fondation Ophtalmologique Adolphe de Rothschild, Paris, France, and treated with PBT at the Centre de Protonthérapie, Institut Curie, Orsay, France. Methods We conducted a retrospective review of all patients with primary ONSM who received PBT (either by itself or following surgery) between January 2006 and January 2019. Neuro-ophthalmic examinations were performed at presentation and after radiotherapy, and, when applicable, after surgery. Meningiomas were measured at the time of diagnosis and at each follow-up MRI examination. Results Sixty patients (50 women, 10 men; mean age, 45.2±11.1y) were included, of whom 29 underwent surgery. At presentation, 52 (87%) of them had decreased vision (average visual acuity: 0.6 logMAR). Fundus examination showed optic disc swelling (n=27; 46.5%), optic disc pallor (n=22; 37.9%), optic disc cupping (n=2; 3.4%), opto-ciliary shunt (n=8; 13.8%), or choroidal folds (n=5; 8.6%). Otherwise, it was unremarkable (n=7; 12.1%). After treatment, visual function was stable overall. Fundus examination showed pallor (n=47; 83.9%), swelling (n=3; 5.4%), or cupping (n=2; 3.4%) of the optic disc, or was unremarkable (n=5; 8.9%). The visual field of 8 patients worsened, while 3 developed asymptomatic retinal hemorrhages. Tumor shrunk significantly in 8 patients at 1 year after PBT and remained stable in size in all others. Patients with opto-ciliary shunts had significantly worse visual outcome than other patients. Retinal abnormalities were observed in 11 patients during follow-up. Conclusion PBT alone or in association with surgery appears to be a safe and efficient treatment for ONSM, reducing the tumor size and stabilizing visual function. The risk of developing radiation retinopathy seems to be higher when patients had upfront surgery.

Radiation-Induced Retinopathy and Optic Neuropathy after Radiation Therapy for Brain, Head, and Neck Tumors: A Systematic Review

“…No significant association was found between the tumor’s prescribed dose and radiation retinopathy prevalence ( p = 0.714). Of these 29 studies, 4 studies reported the prescribed dose to the retina [ 1 , 26 , 33 , 39 ], 6 studies reported the prescribed dose to the optic nerve [ 27 , 33 , 44 , 45 , 46 ], and 5 studies reported the prescribed dose to the chiasm [ 27 , 28 , 33 , 38 ]. No significant association was found between retinopathy prevalence and the dose received by the retina ( p = 0.798) and optic nerve ( p = 0.366).…”

“…Optic neuropathy was observed in 319 patients (prevalence = 2.0% [CI 95% = 0.028–0.034]). The diagnosis time of optic neuropathy was reported in 35 studies, with a mean of 36 months following irradiation (range, 3–108 months) [ 1 , 19 , 22 , 26 , 28 , 35 , 39 , 40 , 41 , 42 , 43 , 45 , 49 , 51 , 52 , 54 , 55 , 59 , 60 , 61 , 62 , 65 , 71 , 73 , 75 , 77 , 79 , 81 , 85 , 87 , 89 ]. Optic neuropathy prevalence was observed at prescribed doses of >50 Gy and <50 Gy at 4.5% and 1.7%, respectively.…”

“… Forest plot of studies that reported radiation-induced retinopathy events [ 1 , 7 , 21 , 23 , 24 , 25 , 26 , 27 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 42 , 44 , 45 , 46 , 47 , 48 , 49 ]. …”

“… Forest plot of the studies that reported radiation-induced optic neuropathy events [ 1 , 15 , 19 , 20 , 21 , 22 , 26 , 28 , 31 , 32 , 33 , 35 , 36 , 38 , 39 , 40 , 42 , 43 , 44 , 45 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , ...…”

Bilateral paediatric optic nerve sheath meningioma

“…Proton beams achieve this through a finite range and narrow beam. A retrospective study by Hage et al 21 looked at 60 patients who underwent PBT for primary ONSMs and found that 85% had either improvement or stability in their visual field examination. Among the 31 patients who underwent PBT alone without surgery in their cohort, 4 developed radiation retinopathy, of which 2 were mild with no change to visual acuity, and no patients developed a definitive radiation optic neuropathy.…”