Long-term results of Gamma Knife Radiosurgery for Postsurgical residual or recurrent nonfunctioning Pituitary Adenomas

Introduction: The aim of this retrospective study was to analyze the long-term outcomes and factors associated with treatment failure of Gamma Knife radiosurgery (GKRS) for postsurgical residual or recurrent nonfunctioning pituitary adenomas (NFPAs). Design and Methods: A total of 148 cases of postsurgical residual or recurrent NFPA patients were enrolled in the study. There were 111 cases with residual tumor and 37 cases with recurrent tumor. The median age was 46.0 years (Range: 10.9-75.8 years). The median tumor volume at GKRS was 3.6 cm(3) (Range: 0.3-74.5 cm(3)), and the median tumor margin dose was 14.0 Gy (Range: 9-20 Gy). Results: Tumor shrunk in 111 patients (75%), remained stable in 17 patients (11.5%), and progressed in 20 patients (13.5%) during a median of 64.5 months (Range: 14.5-236.0 months) of imaging follow-up. The progression-free survival rates were 99%, 91%, 88% and 74% at 1, 3, 5 and 10 years after GKRS, respectively. In a multivariate analysis, tumor margin dose (<13 Gy) was significantly associated with tumor progression (hazard ratio=3.526, 95% confidence interval=1.400-8.877, p=0.007). New hypopituitarism occurred in 22 out of 80 patients (27.5%), including hypogonadism (n=7), hypothyroidism (n=9), hypocortisolism (n=15) and growth hormone deficiency (n=1). In univariate and multivariate analysis, there were no factors significantly associated with new hypopituitarism. Six patients (4.1%) developed new or worsening visual dysfunction. Four patients (2.7%) developed new cranial neuropathy. Conclusion: In this study, GKRS can offer a high tumor control rate as well as a low rate of complications in postsurgical residual or recurrent NFPA patients.