Cesium-131 brachytherapy for central nervous system salvage therapy.

PURPOSE: Salvage therapy for metastatic central nervous system (CNS) lesions remains challenging. Repeat stereotactic radiosurgery (SRS) is sometimes feasible, but subject to high radionecrosis rates. Cesium-131 (Cs-131) brachytherapy seeds packaged inside “tiles” of collagen spacer material may offer an alternative approach. We report a single institution’s experience with this modality. METHODS: Patients with metastatic lesions salvaged with Cs-131 brachytherapy were reviewed. Analyses included treatment characteristics and Kaplan–Meier estimates of overall survival (OS) and local control, while primary tumor outcomes were summarized descriptively. RESULTS: Sixteen patients with metastatic lesions (19 post-operative resection cavities, 17 cases) were reviewed. The most common primary histologies were non-small cell lung cancer (8 cavities, 42.1%) and invasive ductal carcinoma of the breast (3 cavities, 15.8%). One year OS was 70.8%. During follow-up, local failure occurred in 2 of 19 cavities (10.5%). Gross-total resection (GTR) was achieved in 15 cavities (78.9%). All demonstrated local control at a median follow-up of 12 months (full range, 2–39 months). Subtotal or near-total resection (STR/NTR) was achieved in 4 cavities (21.1%). Follow-up data were available for 2 of these cavities (both NTR), and both experienced local failure at 5.3 months. Postoperative cerebrospinal fluid (CSF) leak occurred in 2 patients (12.5%). Radionecrosis within the resection cavity was observed in 3 patients (18.8%) with symptomatic grade ≥ 2 radionecrosis occurring in 1 patient (6.3%). CONCLUSIONS: Salvage therapy with Cs-131 brachytherapy offers effective local control and an acceptable safety profile. Its utility may be greatest following GTR.