Same-Day Radioembolization for Large Hepatocellular Carcinoma (≥ 5 cm) Using Yttrium-90 Resin Microspheres: Protocol for a Multicenter Prospective Registry Study (ISTAR-01)

Abstract Purpose This study aims to evaluate the technical feasibility of same-day yttrium-90 (Y-90) radioembolization in patients with large hepatocellular carcinoma (HCC) (≥ 5 cm) who are predicted to have a low lung shunt fraction (LSF) based on imaging features. Materials and methods This prospective, multicenter, open-label, single-arm registry study will enroll patients with large HCC without imaging features suggestive of high LSF. Eligible patients will undergo same-day planning angiography, technetium-99 m macroaggregated albumin ( 99m Tc-MAA) scintigraphy, and Y-90 radioembolization using resin microspheres. Key eligibility criteria include tumor size ≥ 5 cm, Child–Pugh class A liver function, and absence of imaging findings associated with elevated LSF. Imaging indicators of high LSF include hepatic vein invasion, early hepatic vein enhancement, transjugular intrahepatic portosystemic shunt, and dysmorphic intratumoral vessels ≥ 3 mm. The primary endpoint is the proportion of patients successfully undergoing same-day treatment among those scheduled. Secondary endpoints include objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and treatment-related toxicity. Statistics A total of 139 patients will be enrolled to estimate feasibility, assuming a success rate of 90% with a 5% margin of error at a 95% confidence level. ORR will be compared using the chi-square test, while PFS and OS will be evaluated using the Kaplan–Meier method and compared using the log-rank test. Expected Gain of Knowledge This study will provide prospective evidence regarding the feasibility and clinical outcomes of same-day radioembolization in large HCC. ClinicalTrials.gov identifier NCT06944483