QOL-32. Minimally Invasive Resection with Cesium-131 Brachytherapy: A Cost-Conscious Alternative to Surgery and SRS for Brain Metastases

Abstract INTRODUCTION Surgical resection followed by stereotactic radiosurgery (S+SRS) is standard for brain metastases but may delay radiation and risk loss to follow-up, especially at tertiary centers. Minimally invasive keyhole craniotomy (MIKC) with intraoperative Cesium-131 brachytherapy (Cs-131BT) delivers immediate, cavity-directed radiation while sparing healthy tissue. A prospective study at Ochsner Medical Center (2019–2022) showed favorable local control and low toxicity with MIKC + Cs-131BT. Given rising healthcare costs, we performed a matched cohort study to compare its cost-effectiveness to S+SRS. METHODS Patients treated from 2019–2025 with S+SRS were 1:1 matched to MIKC + Cs-131BT patients by tumor type, age (±10 years), and tumor volume (±30%). Quality-adjusted life years (QALY)-B was calculated as survival (≤2 years) × KPS-derived utilities. QALY-A used post-op ECOG (brachytherapy) and AMPAC (SRS) scores mapped to utilities: 24 = 1.0, 20–23 = 0.8, 15–19 = 0.5, <15 = 0.3. Direct hospital costs included index admission + first SRS or full brachytherapy episode. Incremental Cost-Effectiveness Ratios (ICERs) were calculated per pair as dominant (lower cost, higher QALY), cost-effective (<$50,000/QALY), or dominated (higher cost, lower benefit). RESULTS Among 20 patients treated with brachytherapy, the median direct hospital cost was $14,816, and median QALY-B was 0.50, yielding a median cost per QALY-B of $30,935. In a matched cohort analysis of 13 pairs, median cost was significantly lower in the brachytherapy group ($14,328 vs $25,567, p = 0.0134) with similar QALY-A (0.38 vs. 0.41) across groups. Median total hospital charge was significantly lower for brachytherapy ($93,597 vs. $177,340, p = 0.0006), while net revenue ($40,643 vs. $37,702) and contribution to indirect (CTI) margin ($11,261 vs. $23,554) were comparable. ICER analysis showed 5 dominant, 1 cost-effective, 6 dominated, and 1 excluded pair (ΔQALY ≈ 0). Median ICER was –$9,470.2 (IQR: –$21,397 - $18,686). CONCLUSION MIKC + Cs-131BT was associated with significantly lower hospital costs and improved cost-effectiveness for quality-adjusted survival. These findings support its further evaluation as a cost-conscious alternative to SRS.