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.