CLINICAL-RESULTS OF 24 PITUITARY MACROADENOMAS WITH LINAC-BASED STEREOTACTIC RADIOSURGERY

Purpose: To determine the impact of stereotactic radiosurgery (SRS) on the clinical course, hormonal status, and follow-up CT/MRI scan of pi tuitary macroadenomas. Methods and Materials: From July 1988 to March 1996, W pituitary macroadenomas had been treated using 6 MV linear acc elerator based SRS. They consisted of II (45.8%) prolactinomas, 2 (8.3 %) growth hormone (GH)-secreting tumors, 1 (4.2%) Gushing's disease, 8 (33.3%) nonsecreting (nonfunctioning: NF) tumors, and 2 (8.3%) mixed prolactin-growth hormone (PRL-GH)-secreting tumors (M:F = 12:12; aged 21-61 years). Postoperative irradiation was performed in all cases exc ept for the instance of Gushing's disease. The prescribed dose to tumo r center varied from 10 to 27 Gy (mean 21.1 Gy) using a collimator siz e of 0.5 to 2.5 cm. The follow-up duration ranged from 13 to 89 months (mean 49.2 months). Results from these patients mere compared to our results using conventional radiation. Results: Visual acuity and field defect were improved or became normal in 19 (79.2%) cases. Four (16.7 %) remained unchanged after the treatment. One (4.1%) progressed 6 yea rs after SRS and subsequently had repeat surgery with conventional boo st irradiation. Of the 13 (46.4%) prolactinomas, including two mixed P RL-GH secreting tumors, 11 (84.1%) revealed normal hormonal levels wit hin 1 year after SRS. In contrast, it took 2 years to become normal af ter conventional radiation therapy. In four GH-secreting tumors includ ing two mixed PRL-GH secreting tumors, SRS and conventional methods sh owed similar responses. On follow-up imagings of the 21 patients, the mass was completely resolved in 4 (16.7%), including 3 PRLs and one NF , decreased in 11 (45.8%), and unchanged in 5 (16.7%) with central nec rosis or cysts. One (4.2%) progressed and was reoperated 6 years after treatment. The complications related to SRS were comparable to those from conventional method. Conclusion: Radiosurgery can be used effecti vely in patients with pituitary adenoma. In this study, a more rapid h ormonal and clinical response was achieved with radiosurgery than with conventional pituitary irradiation treatment. (C) 1998 Elsevier Scien ce Inc.