Role of stereotactic radiosurgery in the management of pituitary adenomas

Trans-sphenoidal neurosurgery is the gold standard treatment for pituitary adenomas, but it can be contraindicated or ineffective. Stereotactic radiosurgery is a procedure aimed at controlling hormone hypersecretion and tumor size of pituitary adenomas. This Review discusses the long-term efficacy and adverse effects of stereotactic radiosurgery with the Gamma Knife (R) in secreting and nonsecreting pituitary adenomas. Long-term data confirm the antisecretory efficacy of the procedure (about 50% remission in hypersecreting tumors) but also a previously unknown low risk of recurrence (2-10% of cases). The time to remission is estimated to range from 12 to 60 months. The antitumoral efficacy of this treatment against nonsecreting tumors is observed in about 90% of cases. Hypopituitarism is the main adverse effect, observed in 20-40% of cases. Comparisons with conventional fractionated radiotherapy reveal a lower rate of remission with Gamma Knife (R) radiosurgery, counterbalanced by a more rapid efficacy and a lower rate of hypopituitarism. Short-term follow-up results on stereotactic fractionated radiotherapy suggest a risk of hypopituitarism similar to the one observed with radiosurgery. Therefore, stereotactic radiosurgery is probably still useful to treat some cases of pituitary adenoma, despite the fact that antisecretory drugs, particularly for acromegaly and prolactinomas, are becoming more effective and are well tolerated, thus increasing the probability of success with nonsurgical therapy.