Single Versus Fractionated Gamma Knife Radiosurgery for Nonfunctioning Pituitary Adenomas Close to the Optic Pathway: A Multicenter Propensity Score Matched Study

BACKGROUND AND OBJECTIVES: Gamma Knife radiosurgery (GKRS), typically administered in a single session (S-GKRS), is an effective treatment for nonfunctioning pituitary adenoma (NFPA). For lesions close to the optic pathway, the use of hypofractionated radiosurgery is growing. This study seeks to compare the results of S-GKRS vs fractionated-GKRS (F-GKRS) for NFPAs adjacent to the optic pathway. METHODS: Two cohorts of patients with residual or recurrent NFPAs in contact to the optic pathway were retrospectively included in this study: (1) a group of patients who underwent a 3-day course of F-GKRS in Europe and (2) a group of patients treated with S-GKRS in the United States. A propensity score matching (ratio 1:1) was carried out to obtain and compare 2 homogeneous groups of patients with NFPA. RESULTS: A total of 84 patients were included for analysis (42 in the S-GKRS cohort and 42 in the F-GKRS group). The 2 cohorts did not differ for age, sex, number of previous surgical procedure, tumor volume, and follow-up. The mean follow-up was 60.2 ± 37.0 months and 62.4 ± 37.4 months for F-GKRS and S-GKRS cohort, respectively ( P = .38). The overall tumor control at last follow-up was achieved in 95.2% and 92.9% of patients in F-GKRS and S-GKRS, respectively ( P = .64). The 1-year, 3-year, 5-year, and 7-year progression-free survival rate after F-GKRS was 100%, 97.1%, 97.1%, and 91%, respectively. In the S-GKRS sample, progression-free survival rates were 100%, 100%, 92.5%, and 92.5% at 1, 3, 5, and 7 years after treatment, respectively. Two patients (4.7%) from the F-GKRS cohort and 2 (4.7%) from the S-GKRS cohort sustained visual worsening after radiosurgery ( P = 1.0). CONCLUSION: In the management of NFPAs adjacent to the optic pathway both F-GKRS and S-GKRS had comparable outcomes and risks at 7 years. Future prospective studies including larger cohorts with longer follow-up are needed to confirm our results.