Initial Gamma Knife radiosurgery for nonfunctioning pituitary adenomas: results from a 26-year experience.

Objective: The aim of this study was to evaluate the long-term outcomes of initial Gamma Knife radiosurgery (GKRS) for patients with nonfunctioning pituitary adenomas (NFPAs).

Design And Methods: This was a single-center retrospective study. Eighty-one patients with NFPAs undergoing initial GKRS were enrolled. The median age was 44.9 years (range, 7.2-75.5 years). The median tumor volume was 2.3 cm (range, 0.1-31.3 cm), and the median tumor margin dose was 13.0 Gy (range, 8-22 Gy).

Results: Tumor shrunk in 63 patients (77.8%), remained stable in 9 (11.1%), treatment failure in 9 (11.1%) during a median follow-up of 67.1 months (range, 11.5-263.9 months). The tumor control rates were 100%, 99%, 95%, and 84%, at 1, 3, 5, and 10 years, respectively. In multivariate analysis, tumor volume (≥4 cm) and margin dose (<12 Gy) were associated with treatment failure (hazard ratio (HR) = 7.093, 95% confidence interval (CI) = 1.098-45.083, p = 0.040, and HR = 9.643, 95% CI = 1.108-83.927, p = 0.040, respectively). New apoplexy occurred in seven patients (8.6%) after GKRS with a median time of 39.9 months (range, 11.9-166.8 months). In multivariate analysis, tumor volume (≥10 cm) was a significant risk factor (HR = 10.642, 95% CI = 2.121-53.398, p = 0.004). New hypopituitarism occurred in 14 patients (17.3%). No factors were associated with new hypopituitarism. Four patients (4.9%) developed new or worsening visual dysfunction. No new cranial neuropathy was noted.

Conclusions: In this study, initial GKRS can provide a high tumor control rate, as well as a low incidence rate of complications in NFPAs. GKRS may be an alternative initial treatment for selected NFPAs.