Long-Term Results of Stereotactic Radiosurgery in Secretory Pituitary Adenomas

Abstract

Context: To date, no study reported long-term follow-up results of gamma knife stereotactic radiosurgery (SR). Objective: The aim of the study was to determine long-term efficacy and adverse effects of SR in secreting pituitary adenomas. Design: We conducted a retrospective study of patients treated by SR in the center of Marseille, France, with a follow-up of at least 60 months. Patients: A total of 76 patients were treated by SR for acromegaly (n = 43), Cushing’s disease (CD; n = 18), or prolactinoma (n = 15) as a primary (n = 27) or adjunctive postsurgical treatment (n = 49). Main Outcome Measures: After withdrawal of antisecretory drugs, patients were considered in remission if they had mean GH levels below 2 ng/ml and normal IGF-I (acromegaly), normal 24-h urinary free cortisol, and cortisol less than 50 nmol/liter after low-dose dexamethasone test (CD) or two consecutive normal samplings of prolactin levels (prolactinoma). Results: After a mean follow-up of 96 months, 44.7% of the patients were in remission. Mean time to remission was 42.6 months. Twelve patients presented late remission at least 48 months after SR. Two patients with CD presented late recurrence 72 and 96 months after SR. Forty percent of patients treated primarily with SR were in remission. Target volume and initial hormone levels were significant predictive factors of remission in univariate analysis. Radiation-induced hypopituitarism was observed in 23% patients; in half of them, hypopituitarism was observed after a mean time of 48 to 96 months. Twenty-four patients were followed for more than 120 months; rates of remission and hypopituitarism were similar to the whole cohort. Conclusions: SR is an effective and safe primary or adjunctive treatment in selected patients with secreting pituitary adenomas. Long-term results of Gamma Knife radiosurgery draw attention to the possibility of late recurrence, late remission, and low risk of hypopituitarism.