Long-Term Outcomes After Cyberknife Radiosurgery for Nonfunctioning Pituitary Adenomas.

BACKGROUND AND OBJECTIVES Stereotactic radiosurgery (SRS) has been widely adopted as an important adjunctive treatment modality for managing nonfunctioning pituitary adenomas (NFPAs). However, current studies on the long-term effects of SRS on pituitary adenomas have been largely limited by small sample sizes and short follow-up periods. The aim of this study was to evaluate the long-term outcomes of SRS for NFPAs. METHODS We conducted a retrospective review of 178 patients with NFPAs who received Cyberknife radiosurgery at a single institution between February 2008 and July 2021. Long-term outcomes of tumor control, new-onset hypopituitarism, and new visual disorders were assessed. RESULTS During a median radiological follow-up of 49.7 months (range, 2.5-158.1 months), only 11 (7.0%) patients experienced tumor progression. The progression-free survival at 3, 5, and 10 years was 97.47%, 95.57%, and 93.04%, respectively. New-onset hypopituitarism was diagnosed in 27 (16.9%) patients with a median clinical follow-up duration of 71.2 months (range, 11.5-175.4 months). The median time from SRS to new-onset hypopituitarism was 28.3 months (range, 2.8-101.7 months). The cumulative incidence of new-onset hypopituitarism at 3, 5, and 10 years was 8.47%, 12.43%, and 15.25%, respectively. Biological effective dose >140 Gy and single fraction equivalent dose >16.0 Gy were significant risk factors for new-onset hypopituitarism (P = .046). Other adverse events were experienced by 15 (8.4%) patients, 9 (5.1%) of whom presented with new visual disorders. Development of new visual disorders was associated with a pretreatment tumor volume of >2.5 mL (P = .044). CONCLUSION SRS is an effective and relatively safe means of managing both primary and residual/recurrent NFPAs.