Stereotactic radiosurgery for pituitary adenoma invading the cavernous sinus

Object. The purpose of this study is to determine the efficacy of gamma kni fe radiosurgery (GKS) treatment of pituitary adenomas that have invaded the cavernous sinus. Methods. Sixteen patients were treated with GKS: three with nonfunctional a denomas and 13 with hormone-secreting (seven growth hormone [GH] and six ad renocorticotropic hormone [ACTH]) adenomas. More than 16 Gy and 30 Gy were delivered to the tumor margin for nonfunctioning tumors and functioning tum ors, respectively, keeping the dose to the optic pathways below 10 Guy. The median follow up was 3 years. Tumor growth control was achieved in all cases. In GH-producing tumors, fou r 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-fr ee cortisol < 90 mg/day), two were unchanged, and one showed hormonal recur rence 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 thera py for invading pituitary adenomas, with effectiveness equivalent to conven tional radiation therapy but with less risk of causing radiation-induced in jury to the surrounding structures.