Long-term results of stereotactic radiosurgery to the pituitary gland in Cushing's disease.

Gamma radiation from 60Co delivered with stereotactic technique was given to the pituitary gland in 35 patients, aged 18-65 years, with Cushing's disease. The doses were 70-100 Gy in each single irradiation. The size of the sella turcica was normal in the majority of the patients. The observation time was 3-9 years in 29 patients. Out of them, 14 (48%) obtained clinical remission and normal urinary cortisol after one irradiation. Eight achieved remission after two to four irradiations. In total, 22 out of 29 patients (76%) obtained remission. In 12 of them remission was obtained in 1 year and in another 10 within 3 years. No recurrences were observed. Improvement was seen in 2 patients after one and three irradiations. Bilateral adrenalectomy was performed in 5 patients owing to unsatisfactory effect of irradiation. Pituitary insufficiency with gonadotropin, thyrotropin or corticotropin failure was demonstrated in 12 of 22 patients in remission. This occurred 4 months to 7 years after the first irradiation. Another 6 patients were followed less than 3 years after the first irradiation. Two obtained remission after the first treatment, whereas the other 4 improved. Stereotactic pituitary irradiation is suggested as a non-invasive therapeutic alternative in Cushing's disease for example in patients with considerable surgical risk or as a supplement to pituitary microsurgery.