Gamma Knife radiosurgery for medically and surgically refractory prolactinomas: long-term results

Abstract

Introduction: Prolactinomas are the most common functioning pituitary adenomas. Dopamine agonists (DA) are generally very effective in treating prolactinomas by inducing tumor volume regression and endocrine remission. A minority of patients do not respond to DA or are intolerant because of side-effects. Microsurgical resection when possible is the next treatment option, but cavernous sinus, dural, or bone involvement may not allow for complete resection.

Objective: We reviewed the outcome of patients with medically and surgically refractory prolactinomas treated with Gamma Knife radiosurgery (GKRS) during a 22 years follow-up period.

Methods: We reviewed the patient database at the University of Virginia Gamma Knife center during a 25-year period (1989-2014), identifying 38 patients having neurosurgical, radiological and endocrine follow-up.

Results: Median age at GKRS treatment was 43 years. Median follow-up was 42.3 months (range 6-207.9). 55.3 % (n = 21) were taking a dopamine agonist at time of GKRS. 63.2 % (n = 24) had cavernous sinus tumor invasion. Endocrine remission (normal serum prolactin off of a dopamine agonist) was achieved in 50 % (n = 19). GKRS induced hypopituitarism occurred in 30.3 % (n = 10). Cavernous sinus involvement was shown to be a significant negative prognosticator of endocrine remission. Taking a dopamine agonist drug at the time of GKRS showed a tendency to decrease the probability for endocrine remission.

Conclusion: GKRS for refractory prolactinomas can lead to endocrine remission in many patients. Hypopituitarism is the most common side effect of GKRS.

Keywords: Gamma Knife; Pituitary adenoma; Prolactinoma; Radiosurgery.