Radiosurgery for growth hormone-producing pituitary adenomas

The authors sought to evaluate the effect of gamma knife radiosurgery (GKS) on growth hormone (GH)-producing pituitary adenoma growth and endocrinological response.

From 1993 to 1997, 79 patients with GH-producing pituitary adenomas were treated with GKS. Seventy-six patients had acromegaly. Sixty-eight patients were treated with GKS as the primary procedure. The tumor margin was covered with a 50 to 90% isodose and the margin dose was 18 to 35 Gy (mean 31.3 Gy). The dose to the visual pathways was less than 10 Gy except in one case. Sixty-eight patients (86%) were followed for 6 to 52 months. Growth hormone levels declined with improvement in acromegaly in all cases in the first 6 months after GKS. Normalization of the hormone levels was achieved 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 patients with hyperglycemia regained a normal blood glucose level (p < 0.001). The tumor shrank in 30 (52%) of 58 patients who had been followed for 12 months (p < 0.01), 39 (87%) of 45 patients for more than 2 years (p = 0.02), and 24 (92%) of 26 patients for more than 36 months. In the remainder of patients tumor growth ceased.

Gamma knife radiosurgery for GH-producing adenomas showed promising results both in hormonal control and tumor shrinkage. A margin dose of more than 30 Gy would seem to be effective in improving the clinical status, reducing high blood glucose levels, and normalizing hypertension.