Abstract No. 336 Radiation Segmentectomy Outcomes of Second-Week Yttrium-90 Glass Microspheres Vials for Treating Hepatocellular Carcinoma

Radioembolization dosimetry is vital to optimizing therapy. The same effective radiation dose can be delivered on different days by altering the microsphere specific activity. First-week glass administrations have a high specific activity and small number of microspheres. Conversely, second-week administrations have a low specific activity and large number of microspheres. Current literature supports treatment in week 1. We evaluated the treatment response and adverse events of radiation segmentectomy for HCC utilizing first- and second-week glass microspheres. A single-institution retrospective review of patients with HCC treated with radiation segmentectomy using Y90 glass microspheres ( ≥ 200 Gy) between January 2019-2023 was performed. 19 patients were treated with first-week vials (Group 1) and 65 patients with second-week vials (Group 2). All patients had compensated liver function at the time of the procedure (total bilirubin < 2.0 mg/dL) and were without extrahepatic disease. Response was determined by cross-sectional imaging at 3, 6, and 12 mo post treatment using LI-RADS criteria. Incidence of acute liver injury and 30-day admission were recorded. One-tail T-test and chi-square analysis was used. Patient age, target volume, and initial tumor size were similar between the two groups, though dose administered was significantly different (Table 336.1). There was a significant difference in tumor viability at the 3 mo follow-up (p = 0.00154) favoring Group 2, with a trend toward better response in Group 2 at 6 and 12 mo (p = 0.0609 and 0.0889, respectively) (Tables 336.2 and 336.3). Acute liver injury and 30-day admission rates were not significantly different between the groups (Table 336.4). Utilizing second-week glass Y90 vials for radiation segmentectomy is safe and effective with comparable outcomes to first-week vials.