VERSECRETION of hormone from pituitary adenomas can result in significant incidences of morbidity and reduced life expectancies for affected patients. 7 Whereas tumor control and preservation of pituitary func- tion is adequate for nonhormone-producing tumors, cor- rection of endocrinopathies is critical to good outcomes for patients with hormone-producing pituitary adenomas. Surgical resection of pituitary adenomas as a primary treat- ment, generally performed through a transsphenoidal ap- proach, is able to normalize hormone levels rapidly for 57 to 91% of patients. 2,8,14,33,41–43 Unfortunately, patients with persistent or recurrent endocrinopathies after surgical resec- tion achieve biochemical remission less frequently after re- peated surgery. 1,9,38 Fractionated external beam radiation therapy results in clinical remission of symptoms for many patients with hormone-secreting tumors. 7,24,29,40 Neverthe- less, radiotherapy frequently causes hypothalamopituitary dysfunction, typically requires several years to correct hor- mone overproduction, and is associated with the risk of radiation-induced neoplasms. 3,5,34 In recent years radiosur- gery has been increasingly used as an alternative to surgery or radiation therapy to manage cases of pituitary adeno- mas. 14,16–18,20,26–28,32,44,46 In this report, we review our experi- ence with radiosurgery in patients harboring hormone-pro- ducing pituitary adenomas and analyze factors associated with biochemical remission. Clinical Material and Methods Patient Population Clinical, radiological, and endocrinological information obtained in 59 patients with hormone-producing pituitary adenomas was retrieved from a prospectively maintained computer database. All patients had undergone radiosur- gery at the Mayo Clinic in Rochester, Minnesota, between January 1990 and November 1999. Twelve patients with ACTH-producing tumors who had undergone adrenalecto- my previously were excluded, and adequate follow up was J. Neurosurg. / Volume 97 / September, 2002 J Neurosurg 97:525–530, 2002 Results of stereotactic radiosurgery in patients with hormone-producing pituitary adenomas: factors associated with endocrine normalization BRUCE E. POLLOCK, M.D., TODD B. NIPPOLDT , M.D., SCOTT L. STAFFORD, M.D., ROBERT L. FOOTE, M.D., AND CHARLES F. ABBOUD, M.D. Department of Neurological Surgery, and the Divisions of Endocrinology, Metabolism, Nutrition, Internal Medicine, and Radiation Oncology, Mayo Clinic and Foundation, Rochester, Minnesota Object. The goal of this study was to determine factors associated with endocrine normalization after radiosurgery is performed in patients with hormone-producing pituitary adenomas. Methods. Between 1990 and 1999, 43 patients with hormone-producing pituitary adenomas underwent radiosur- gery: 26 patients with growth hormone (GH)–producing tumors, nine with adrenocorticotrophic hormone–producing tumors, seven with tumors that produced prolactin (PRL) alone, and one with a tumor that secreted both GH and PRL. The median patient age was 42 years. Thirty-seven patients (86%) had undergone surgery earlier and in 30 (70%) there was tumor extension into the cavernous sinus. The product-limit method was used to calculate endocrine normaliza- tion while patients were not receiving any hormone-suppressive medication. The median follow-up period after radio- surgery was 36 months (range 12–108 months). In 20 patients (47%) there was normalization of hormone secretion at a median of 14 months (range 2–44 months) after radiosurgery; no correlation was found between tumor type and cure. Actuarial cure rates were 20, 32, and 61% at 1, 2, and 4 years posttreatment. Multivariate analysis demonstrated that the absence of hormone-suppressive medi- cations at the time of radiosurgery (relative risk 8.9, 95% confidence interval [CI] 1.2–68.7, p = 0.04) and maximum radiation doses greater than 40 Gy (relative risk 3.9, 95% CI 1.3–11.7, p = 0.02) correlated with an endocrine cure. A new anterior pituitary deficiency developed in seven patients (16%), temporal lobe necrosis was identified in two pa- tients, an asymptomatic internal carotid artery stenosis was detected in two patients, and unilateral blindness occurred in one patient. Conclusions. Radiosurgery provides an endocrine cure for many patients with persistent or recurrent hormone-pro- ducing pituitary adenomas. Further study is needed to determine whether pituitary hormone–suppressive medications have a radioprotective effect. KEY WORDS • acromegaly • Cushing disease • pituitary adenoma • prolactin • radiosurgery O 525 Abbreviations used in this paper: ACTH = adrenocorticotrophic hormone; GH = growth hormone; ICA = internal carotid artery; IGF-I = insulin-like growth factor I; PRL = prolactin; UFC = uri- nary free cortisol.