Long-term safety and efficacy of staged stereotactic radiosurgery with Ommaya reservoir aspiration for large cystic brain metastases.

purposeManaging large cystic brain metastases (CBMs) presents significant challenges. This study evaluated the feasibility of cyst aspiration via Ommaya reservoir (OR), followed by staged stereotactic radiosurgery (S-SRS) for large CBMs.

methodsA retrospective review of patients with large CBMs (> 10 mL post-aspiration and/or located in the primary motor cortex) who underwent S-SRS was conducted. The radiosurgical protocol involved delivering 24–30 Gy in two fractions, separated by 3–4 weeks. Outcome measures included overall survival (OS), local control, and leptomeningeal metastases (LMs), with competing-risk analyses used as appropriate.

resultsThirty-two consecutive patients with 34 large CBMs were included. The median age was 71 years. Primary malignancies included lung (20), breast (5), genitourinary (4), gastrointestinal (2), and melanoma (1). Median intact CBMs volume was 34.1 mL (IQR 22.9–53.8). Median volume reduction at each S-SRS session relative to intact CBMs was 62% (IQR 42–73) and 82% (IQR 66–87). One- and 2-year OS rates after S-SRS were 50% and 33%, with a median survival of 10.2 months. Concurrent targeted therapy (TT)/immunotherapy (IT) was the only independent factor associated with improved OS (HR 0.31, 95% CI 0.11–0.86). Cumulative 1- and 2-year local failure rates were 23% and 36%, respectively, while LM rates were 13% and 26%. One serious adverse event occurred due to ventricular perforation caused by the catheter tip.

conclusionOR aspiration, followed by S-SRS, is an effective, minimally invasive option for large CBMs. Concurrent TT/IT was associated with improved survival, but long-term disease control remains challenging.