Optic gliomas: radiation therapy and prognosis.

A retrospective study was performed of 30 patients with optic gliomas referred to the Royal Marsden Hospital between 1951 and 1981. Twenty-nine of these had progressive disease, and were treated with radiotherapy. At presentation 12 (41%) had visual deficit to the extent of at least one blind eye. Visual acuity improved following treatment in 10 (43%) of 23 evaluable patients, was stable in 11 (48%) and deteriorated in 2 (9%). There was increase in visual fields in 4 (18%) of 22 evaluable patients, and no change in the remaining 18 (82%). Overall 26/29 (90%) of irradiated patients remained free from disease progression at a median follow-up period of 10 years. The probability of survival was 100% at five years following radiotherapy, and 93% at 10 years and also at 15 years. In view of the substantial morbidity and mortality in reported series, and the tendency for referral of more serious cases to a radiotherapy center, we conclude from our results that radiotherapy is effective in preventing progression of optic glioma, and that treatment early in the course of the disease is indicated to minimize the associated visual deficit.