Yttrium-90 Radiation Segmentectomy of Hepatocellular Carcinoma: A Comparative Study of the Effectiveness, Safety, and Dosimetry of Glass-Based versus Resin-Based Microspheres.

Purpose: To evaluate the differences in safety, effectiveness, and dosimetry between glass-based and resin-based ablative yttrium-90 (Y) transarterial radioembolization (TARE) of hepatocellular carcinoma (HCC).

Materials And Methods: Using the modified Response Evaluation Criteria in Solid Tumors and Common Terminology Criteria for Adverse Events, both tumor response and adverse events (AEs) were assessed at 3 months after Y-TARE. Post procedure Y-bremsstrahlung single-photon emission computed tomography/computed tomography voxel-based dosimetry analysis was used to create tumor dose (TD) and normal tissue dose (NTD) volume histograms, and to calculate tumor particle loading and specific activity. The TD and NTD receiver operating characteristic curves evaluated the dose threshold able to predict objective (partial or complete) and complete tumor responses in addition to any-grade and grade ≥3 AE incidences. The chi-square test and Student t-test were used to assess variable differences where appropriate.

Results: Between 2019 and 2020, 81 patients with HCC (20 in the resin-based cohort and 61 in the glass-based cohort) underwent ablative Y-TARE. The resin-based cohort had more males (89% vs 65%, P = .03), lower tumor-to-normal ratio (1.81 ± 0.39 vs 2.22 ± 0.94, P = .03), higher tumor particle loading (40,172 particles/mL ± 28,039 vs 17,081 particles/mL ± 12,555, P = .0001), lower specific activity (158 Bq/particle ± 3 vs 1,058 Bq/particle ± 331, P = .001), and lower mean TD (308 Gy ± 210 vs 794 Gy ± 523, P = .0002) than the glass-based cohort. No significant differences in baseline characteristics or posttreatment AEs were noted. The overall objective and complete response rates were 85% (95% resin-based vs 82% glass-based; P = .1) and 65% (95% resin-based vs 56% glass-based; P = .003), respectively. The mean TD thresholds able to predict the objective and complete responses were 176 Gy and 247 Gy for resin-based radioembolization and 290 Gy and 481 Gy for glass-based radioembolization, respectively. A maximum NTD of 999 Gy predicted any-grade AEs in glass-based ablative Y-TARE.

Conclusions: Compared with glass-based ablative Y-TARE, resin-based ablative Y-TARE can offer comparable safety and effectiveness profiles for patients with HCC. The impact of the significantly different tumor particle loading, particle specific activities, and delivered TDs on tumor response outcomes merits further investigation.