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.