Results of radiotherapy in the treatment of acromegaly: lack of ophthalmologic complications.

Between 1956 and 1988, 25 patients were treated with radiotherapy for acromegaly. Acromegalic features were present in 24 (96%), visual field deficits in 4 (16%), and suprasellar extension was present in 7 patients (28%). The median growth hormone level was 40.2 ng/ml (range: 13.8-105) in 15 patients. Initial therapy consisted of radiotherapy alone (19 patients) or surgery followed at some interval by radiation (6 patients). The radiation therapy was administered with megavoltage equipment in 23 (92%) patients and orthovoltage equipment in 2 patients. The median total dose was 46 Gy (range: 24-53.44 Gy) with 21 patients receiving at least 45 Gy. With a median follow-up of 53 months (range: 18-205), 2 of the 19 patients treated with radiotherapy alone have required surgery for symptomatic recurrences. Both are alive and in remission at 69 and 158 months following craniotomy. Thus, the success of radiotherapy as a primary modality in this series is 17/19 (89%). None of the six patients treated postoperatively have recurred. At the time of last follow-up the visual fields remained normal and visual acuity stable in the 21 patients with no pre-existing visual deficits. The four patients with prior visual field deficits improved with therapy. There were no cases of radiation optic neuropathy, brain necrosis or second intracranial malignancies. Seven patients (28%) had evidence of hypopituitarism attributed to the radiotherapy. Growth hormone levels after radiotherapy showed a median of 5.4 ng/ml (range: 3.2-40.0) in 15 patients. Eleven of 15 patients (73%) had growth hormone levels less than 10 ng/ml. Radiation use in acromegaly remains a safe and effective modality assuming careful attention is paid to technique, total dose, and fraction size.