Ablative Radioembolization Dosing Thresholds for Glass Microspheres Predictive of Complete Imaging Response and Survival in Patients with Hepatocellular Carcinomas Larger than 4 cm: A Multi-institution Retrospective Analysis.

PURPOSE: To evaluate complete imaging response (CR) as a biomarker for survival and compare dosimetry models that predict CR in hepatocellular carcinomas (HCCs) ≥ 4 cm treated with glass microsphere transarterial radioembolization (TARE).

MATERIALS AND METHODS: This retrospective multicenter analysis included 112 consecutive patients who underwent TARE for untreated HCC ≥ 4 cm between June 2018 and June 2024. Imaging response was assessed by modified Response Evaluation Criteria in Solid Tumors. Post-TARE single photon emission computed tomography (SPECT)/computed tomography (CT) were analyzed using voxel-based dosimetry software to estimate dose. Associations between dose, imaging response, and clinical outcomes were evaluated.

RESULTS: Fifty-eight patients (51.8%) had CR 3 months after TARE. CR was associated with improved overall survival (OS). Post hoc estimated doses were significantly higher in patients with CR: 592-Gy versus 316-Gy single-compartment perfused dose, 482-Gy versus 213-Gy D95, and 828-Gy versus 401-Gy D50. Multiple dose thresholds were correlated with CR and OS including D95. Area under the curve by receiver operating characteristic analysis and modeled CR probability did not differ significantly between single-compartment and voxel-based dose estimates.

CONCLUSIONS: For HCC > 4 cm, CR at 3 months was correlated with OS. Higher single-compartment dose thresholds or voxel-based dosimetry thresholds than currently recommended may better predict CR in HCC tumors ≥ 4 cm treated with glass microsphere TARE.