Radiosurgery for growth hormone-producing pituitary adenomas

Object. The authors sought to evaluate the effect of gamma knife radiosurge ry (GKS) on growth hormone (GH)-producing pituitary adenoma growth and endo crinological response. Methods. From 1993 to 1997, 79 patients with GH-producing pituitary adenoma s were treated with GKS. Seventy six patients had acromegaly. Sixty-eight p atients were treated with GKS as the primary procedure. The tumor margin wa s covered with a 50 to 90% isodose and the margin dose was 18 to 35 Gy (mea n 31.3 Gy). The dose to the visual pathways was less than 10 Gy except in o ne case. Sixty-eight patients (86%) were followed for 6 to 52 months. Growt h hormone levels declined with improvement in acromegaly in all cases in th e first 6 months after GKS. Normalization of the hormone levels was achieve d in 23 (40%) of 58 patients who had been followed for 12 months and in 96% of cases for more than 24 months (43 of 45), or more than 36 months (25 of 26), respectively. With the reduction of GH hormone levels, 12 of 21 patie nts with hyperglycemia regained a normal blood glucose level (p < 0.001). T he tumor shrank in 30 (52%) of 58 patients who had been followed for 12 mon ths (p < 0.01), 39 (87%) of 45 patients for more than 2 years (p = 0.02), a nd 24 (92%) of 26 patients for more than 36 months. In the remainder of pat ients tumor growth ceased. Conclusions. Gamma knife radiosurgery for GH-producing adenomas showed prom ising results both in hormonal control and tumor shrinkage. A margin dose o f more than 30 Gy would seem to be effective in improving the clinical stat us, reducing high blood glucose levels, and normalizing hypertension.