Long-term efficacy of fractionated conformal radiotherapy for the management of primary optic nerve sheath meningioma.

Background/aim: Fractionated conformal radiotherapy (FCRT) is now used to treat vision-threatening optic nerve sheath meningioma (ONSM), but long-term efficacy and safety data are lacking; the purpose of this study was to assess these key data.
Methods: This is a retrospective chart review with prospective follow-up of adult patients treated with FCRT for primary ONSM at four academic medical centres between 1995 and 2007 with ≥10 years of follow-up after treatment.
Results: 16 patients were identified with a mean post-treatment follow-up of 14.6 years (range: 10.5-20.7 years). The mean age at symptom onset was 47.6 years (range: 36-60 years). FCRT was performed at a mean of 2.3 years after symptom onset (range: 0.2-14.0 years). At last follow-up, visual acuity had improved or stabilised in 14 of the 16 (88%) patients, and 11 (69%) had retained or achieved ≥20/40. The mean deviation on automated perimetry remained stable (-14.5 dB pretreatment vs -12.2 dB at last follow-up; p=0.68, n=10). Two (11%) patients had persistent pain, proptosis or diplopia, compared with six (38%) pretreatment (p=0.11). Two (13%) patients developed radiation retinopathy more than 6 months after completion of therapy, one (50%) of whom had worse visual acuity compared with pretreatment. No patient developed tumour involvement or radiation damage in the fellow eye.
Conclusion: FCRT stabilises or improves visual function in patients with primary ONSM and is associated with a low risk of significant ocular sequelae. This treatment should be considered instead of surgery in patients with primary ONSM who require intervention due to loss of visual sensory and/or ocular motor function.
Competing Interests: Competing interests: None declared.
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