The Role of Gamma Knife Radiosurgery for the Treatment of Pituitary Adenomas

ABSTRACT

The treatment of choice for symptomatic pituitary adenomas varies according to the hormone secreting types of the adenoma and can include pharmacology, surgery, or radiotherapy. The recent development of radiological imaging and microsurgery has made surgery the treatment of choice for most pituitary tumors. However, the long-term tumor control rate after microsurgery varies from 50% to as high as 80%. During the last 38 months(1990. 5-1990. 9., 1991. 5-1994. 2), 34 cases of pituitary adenomas were treated by gamma knife at Asan Medical Center. There were 11 cases of prolactinomas, 9 cases of acromegaly, 8 cases of ACTH-secreting tumors and 6 cases of non-functioning tumors. Seventeen patients underwent gamma knife radiosurgery for recurrent or remaining tumors after resective surgery. Another 17 patients were treated primarily with gamma knife. In microadenomas, the mean tumor volume was 221 cumm and the mean marginal dose was 33.1 Gy. In microadenomas, the mean tumor volume was 2690 cumm and the mean marginal dose was 2.6 Gy. Twenty-seven patients have had an average follow-up period of 26 months with a range from 3 to 48 months. As a result, five out of eight prolactinoma patients had normalization of prolactin hypersecretion and seven patients showed clinical cure. On follow-up imaging studies, five out of seven tumors showed no changes in their size, while two showed marked reduction. Two out of four ACTH-producing tumor patients showed normalization of 24 hour urine cortisol levels. On follow-up imaging studies of the two cases, the tumor of one patient disappeared and the other one showed no change. Three out of six acromegalic patients showed clinical responses. Two out of five non-functiong tumors showed reduction in size and three showed no changes. In conclusion, gamma knife radiosurgery seems to be effective as adjuvant therapy for the treatment of remaining or recurrent pituitary adenomas after surgery and primary treatment modality in selective patients.