Stereotactic radiosurgery for pituitary adenoma invading the cavernous sinus

Abstract

Object. The purpose of this study is to determine the efficacy of gamma knife radiosurgery (GKS) treatment of pituitary adenomas that have invaded the cavernous sinus. Methods. Sixteen patients were treated with GKS: three with nonfunctional adenomas and 13 with hormone-secreting (seven growth hormone [GH] and six adrenocorticotropic hormone [ACTH]) adenomas. More than 16 Gy and 30 Gy were delivered to the tumor margin for nonfunctioning tumors and functioning tumors, respectively, keeping the dose to the optic pathways below 10 Gy. The median follow up was 3 years. Tumor growth control was achieved in all cases. In GH-producing tumors, four of six cases evaluated were endocrinologically normalized (serum GH < 10 mIU/L, somatomedin C < 450 ng/ml), and the remaining two cases also showed a steady decrease in the GH and somatomedin level. In ACTH-producing tumors, three of six cases were endocrinologically normalized (24-hour urinary-free cortisol < 90 mg/day), two were unchanged, and one showed hormonal recurrence 3 years after radiosurgery. Notably, there were no cases of permanent hypopituitarism or visual symptoms caused by radiosurgery. Conclusions. The authors data indicate that GKS can be a safe salvage therapy for invading pituitary adenomas, with effectiveness equivalent to conventional radiation therapy but with less risk of causing radiation-induced injury to the surrounding structures.