[RADIOSURGERY FOR PITUITARY ADENOMAS]

Pituitary adenomas represent one of the most common types of intracranial tumors, accounting for 10-20% of intracranial tumors. While their macroscopic appearance and anatomical location are relatively homogeneous, pituitary tumors differ widely, generating a variety of neurological and endocrine clinical sequelae. Treatment options include hormone suppressive medical therapy, microscopic or endoscopic neurosurgical resection, radiosurgery, radiation therapy, or observation depending on the biochemical profile and the clinical status of the patient. Some pituitary adenomas spread locally to invade surrounding meninges (Dura) and cavernous sinus, hampering a complete surgical resection. Radiosurgery is most commonly utilized as adjunctive treatment following incomplete surgical resection leaving residual tumor, tumor recurrence, or failure of medical therapy. We present a comprehensive literature review of the radiosurgery series for treatment of different pituitary adenomas including nonfunctioning adenomas, ACTH- and GH-secreting adenomas, as well as prolactinomas. While post-radiosurgery radiographic tumor control for nonfunctioning adenomas is excellent, typically at 90%, the rates of endocrine biochemical remission for functioning adenomas are lower than the tumor control rates. A higher dose is needed to attain endocrine remission as compared to attaining only tumor control. The highest endocrine remission rates are achieved by patients with Cushing's disease and the lowest in those with prolactinomas. The most common complication of radiosurgery is delayed hypopituitarism followed by cranial neuropathies. The effect of suppressive medications on radiosurgery outcomes remains controversial. Due to the rare but well-documented occurrence of late recurrence following endocrine remission, long-term and rigorous clinical and radiographic follow-up is necessary for all pituitary adenoma patients.