Fractionated conformal radiotherapy for management of optic nerve sheath meningiomas: Long-term outcomes of tumor control and visual function at a single institution

Purpose: To provide the long-term outcomes of patients treated with fractionated conformal radiotherapy (FCRT) for presumed optic nerve sheath meningiomas (ONSMs). Patients and Methods: Between 1995 and 2002, 9 patients with a presumed ONSM were treated with FCRT at our institution. The indications for FCRT were significant visual dysfunction at presentation, progression of visual dysfunction during a period of observation, tumor growth documented by sequential imaging, or a combination of these findings. In 2 patients, FCRT was performed as adjuvant therapy, and in 7, it was the initial and primary treatment. Results: Of the 9 patients, 6 were women and 3 were men, with a mean age of 47 years. All 9 patients had evidence of optic nerve dysfunction in the affected eye, characterized by reduced visual acuity, a visual field defect, and a relative afferent pupillary defect. In addition, 2 patients had proptosis and 1 had diplopia. The mean follow-up period was 98 ± 31.7 months (median, 90; range, 61-151). After FCRT, the visual function improved in the 7 patients who had undergone FCRT as the primary treatment. However, 2 patients who were blind in their affected eye at FCRT remained blind. In 4 of the 7 patients with improvement, the improvement was documented within 1-3 months after FCRT. The tumor control rate was 100%. Proptosis and diplopia also regressed in 100% of patients. At 2 years after FCRT, 1 patient had developed radiation retinopathy. Conclusion: The results of our study have shown that FCRT is a safe and effective treatment of ONSMs, affording satisfactory long-term tumor control, good functional outcome, and low treatment morbidity. FCRT should be considered the treatment of choice for patients with presumed ONSMs for whom the treatment has been deemed appropriate.