Gamma Knife radiosurgery as the initial treatment for elderly patients with nonfunctioning pituitary adenomas.

Purpose: The aim of this study was to investigate the efficacy and safety of initial Gamma Knife radiosurgery (GKRS) for elderly patients with nonfunctioning pituitary adenomas (NFPAs).

Methods: We retrospectively reviewed 45 elderly patients underwent GKRS as the initial treatment for NFPAs at our institution between December 2007 and December 2017. Patients' radiographic and clinical data were collected.

Results: The median age of patients at the time of GKRS was 71 years (range 65-82 years). The median tumor volume was 2.6 cm (range 0.3-21.8 cm). The median marginal dose was 13 Gy (range 6-23 Gy). The median maximum dose to the optic apparatus was 6.5 Gy (range 2.3-10.3 Gy). Thirty-five patients (77.8%) achieved tumor regression, 6 patients (13.3%) had tumor stable and 4 patients (8.9%) occurred tumor progression during a median radiological follow-up time of 51.4 months (range 11.1-158.7 months). The crude tumor control rate was 91.1%. The actuarial tumor control rates were 100%, 95.0%, 87.6%, and 87.6%, at 1, 3, 5, and 10 years after initial GKRS, respectively. New-onset hypopituitarism occurred in 6 patients. Two patients with pre-GKRS visual dysfunction developed further deterioration of visual function. No other radiation-induced complications were noted.

Conclusion: Initial GKRS can provide a high tumor control rate as well as low risk of postradiosurgical complications for elderly patients with NFPAs. Attention should be paid to avoid radiation-related adverse effects including hypopituitarism, optic neuropathy and cranial neuropathy in elderly patients.