OBJECTIVE: Stereotactic radiosurgery (SRS) offers excellent tumor control for pituitary adenoma (PA)
however, treatment failure occasionally necessitates salvage surgery. Comprehensive studies on salvage surgical outcomes for recurrent PA after SRS remain scarce. This study aimed to elucidate the outcomes of salvage endonasal transsphenoidal surgery (sETS) for progressive PA failing SRS. METHODS: This retrospective, two institution-based cohort study analyzed data from patients who underwent sETS for progressive PA failing SRS. Progression-free survival (PFS), disease-specific survival (DSS), and neurological and endocrinological outcomes in the sETS group were analyzed and compared with those in the primary ETS (pETS) group after propensity score matching using the following variables: age at surgery, maximum tumor diameter, highest Knosp-Steiner classification, and tumor type. RESULTS: Thirteen sETS patients (8 males [62%], median age at surgery of 56 years) with 5 nonfunctioning (39%), 6 corticotropic (46%), and 2 other functioning (15%) PAs who received median (range) follow-up of 125 ( 23-169) months were included. None of the patients experienced new neurological deficits or death after sETS. The median (range) tumor resection rate was 90% (80%-100%). The 5-year PFS and DSS rates were 55% and 77%, respectively. All 4 patients (31%) who experienced recurrence after sETS had corticotropic tumors. In the matched cohort analysis between the sETS group with 12 patients and the pETS group with 12 patients, no significant differences were observed in surgical outcomes. PFS rates were marginally higher in the sETS group than in the pETS group (80% vs 49% at 3 years, p = 0.216, log-rank test), and DSS was similar between the two groups (p = 0.543, log-rank test). CONCLUSIONS: The authors' results indicate that ETS can be safely performed as a salvage treatment after failed SRS with low complication rates and satisfactory tumor control in treatment-resistant PA.