Gamma knife radiosurgery for acromegaly: Outcomes after failed transsphenoidal surgery

OBJECTIVE: This study evaluates the safety and efficacy of g3mma knife radiosurgery (GKRS) in patients with a growth hormone-secreting aclenorr a. i METHODS: A retrospective review of data collected from a prospective database of GKRS patients between January 1988 and September 2006 6as performed in patients with acromegaly. Successful endocrine outcome was clefine Ji as normalization of the insulin-like growth factor level. Tumor volume was also asses!,ecl. At least 18 months of follow-up was available in 95 patients who received radio I;urgery during the study period. Mean endocrine follow-up was 57 months (range, 1 -l 68 mo). RESULTS: Normal insulin-like growth factor levels were achil'wecl in 50 patients (53%) at an average time of 29.8 months after radiosurgery (median! 23.5 mo). A decrease in tumor volume control was achieved in 83 (92%) of 90 patien I ts. Five patients (6%) had no change in tumor volume, and two patients (2%) had an ir crease in tumor volume. New endocrine deficiencies developed in 32 patients (34%),:lFour patients developed new-onset partial visual acuity deficits; three of these patients h i)d received previous conventional fractionated radiation therapy. CONCLUSION: GKRS is a complementary treatment for rec 'Irrent or residual growth I hormone-secreting pituitary adenomas. Although infrequent,,iumor growth, new-onset pituitary hormone deficiency, recurrence, and neurological lysfunction require careful clinical, radiological, and endocrinological follow-up.