Cesium-131 collagen tile brachytherapy for salvage of recurrent intracranial metastases.

Purpose: Management of brain metastases (BM) that recur after stereotactic radiosurgery (SRS) (rBM) is challenging. We reviewed our experience with resection with Cs-131 collagen tile brachytherapy for rBM.

Methods: Patients with rBM after SRS salvaged with resection and Cs-131 brachytherapy were reviewed. Analyses included descriptive statistics, Kaplan-Meier for overall survival (OS), Fine and Gray modeling for subgroup comparisons, and cumulative incidence of LF (CILF).

Results: Thirty-one patients (38 surgical cavities) were reviewed; primaries were most commonly breast (37%) or non-small cell lung cancer (26%). All BMs had received prior SRS to a median 20 Gy in 1 fraction at a median 12.3 months before tile implantation; disease in 32 cavities (84%) was gross totally resected. At a median patient follow-up time of 11.8 months, LF developed in 6 of 38 cavities (16%); with CILF 7.9% at 6 months and 13% at 1 year. Risk factors for LF included > 1 prior radiation courses (HR 2.44; p = 0.001), subtotal resection (HR 6.99; p = 0.015), tumor volume (HR 1.04; p = 0.006), and degree of dural contact (p < 0.001). One-year OS rate was 65.8%. Three cavities (8%) among two patients (6%) developed grade 2 + radionecrosis. Two patients developed classical leptomeningeal disease (LMD) and two patients had nodular dural seeding for an overall incidence of LMD of 12.9%.

Conclusions: Salvage resection with Cs-131 collagen tile brachytherapy for rBM after SRS provides favorable local control with minimal toxicity. Lesion characteristics may help to identify patients at increased risk for LF.