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

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). 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 cm3 (range, 0.1–31.3 cm3), and the median tumor margin dose was 13.0 Gy (range, 8–22 Gy). 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 cm3) 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 cm3) 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. 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.