Stereotactic radiosurgery for patients with ACTH-producing pituitary adenomas after prior adrenalectomy

PURPOSE: To review the results of stereotactic radiosurgery for patients with adrenocorticotropic hormone (ACTH)-producing pituitary adenomas after bilateral adrenalectomy. METHODS AND MATERIALS: Eleven patients with ACTH-producing pituitary adenomas after bilateral adrenalectomy underwent radiosurgery between 1990 and 1999. Nine patients had documented tumor growth, hyperpigmentation, and elevated ACTH levels (median 920 ng/mL) at the time of radiosurgery. Five of these patients had tumor enlargement despite prior fractionated radiotherapy (median dose 50 Gy). Two patients were treated prophylactically within 1 month of their adrenalectomies to prevent future tumor growth. The median follow-up was 37 months (range 22-74). RESULTS: Tumor growth control was achieved in 9 patients (82%); 2 patients had had continued tumor growth after radiosurgery. The ACTH levels decreased a median of 66% (range -99% to +27%); 4 patients had normal ACTH levels. Three patients had radiation-related complications, including diplopia (n = 2), ipsilateral blindness (n = 1), testosterone/growth hormone deficiency (n = 1), and asymptomatic temporal lobe radiation necrosis (n = 1): all had received prior radiotherapy. One patient who had undergone three prior resections and radiotherapy died 59 months after radiosurgery despite two additional attempts at tumor resection. CONCLUSION: Although our experience is limited, it appears that radiosurgery provides tumor control for most patients with ACTH-producing pituitary adenomas who have undergone bilateral adrenalectomy.