Achieving Complete Pathologic Necrosis in HCC using Y90 Radiation Segmentectomy prior to Liver Transplant: A Comprehensive Authorized User Parameter Analysis

To determine authorized user parameters predictive of complete pathologic necrosis (CPN) in hepatocellular carcinoma (HCC) treated with radiation segmentectomy (RS).

Materials and Methods:

A single institution, retrospective, post-treatment Bremsstrahlung SPECT CT voxel-based dosimetry analysis of 61 tumors treated with RS as a subset from a previously published cohort (1) was performed using Simplicit90Y software (Boston Scientific). Specific activity (SA) was defined per an updated glass microsphere (TheraSphere, Boston Scientific) estimation (2). ROC curves and Mann-Whitney U tests were performed using SPSS v.28 with significance set at < 0.05.

Results: Median SA (1242 vs 867 Bq, p=0.018), tumor dose (1086 vs 738 Gy, p=0.007), angiosome normal parenchyma dose (490 vs 309 Gy, p=0.005), and total angiosome dose (577 vs 352 Gy, p=0.005) were higher in the CPN (n=43) vs non-CPN (n=18) cohort. ROC analysis (AUC, Sensitivity, Specificity) demonstrated that an SA ≥ 570 Bq (0.69, 88%, 50%), tumor dose ≥ 844 Gy (0.72, 76%, 67%), angiosome normal parenchymal dose ≥ 420 Gy (0.73, 60%, 78%), and total angiosome dose ≥ 439 Gy (0.73, 70%, 67%) were predictive of CPN (p< 0.05). No statistical difference was noted between the tumor or angiosome particle densities, tumor volume, or angiosome volumes in the CPN and non-CPN cohort.

Subgroup ROC analysis of tumors that received SA < 570 Bq (n=15), a tumor dose ≥451 Gy (0.83, 100%, 67%), and total angiosome dose ≥ 263 Gy (0.85, 83%, 89%) were predictive of CPN (p< 0.05). An average angiosome particle density ≥ 11.4 k/ml (0.81, 83%, 79%) was 83% sensitive and 79% specific to predict CPN in this subgroup (p< 0.05). There were no statistically significant independent predictors of CPN in patients who were treated with SA≥570 Bq.

Eighty-eight percent of tumors that met all treatment thresholds achieved CPN (n=23/26) vs 0% that did not meet a single threshold (n=0/7).

Conclusion:

Higher specific activity, tumor dose, angiosome normal parenchymal dose, and total angiosome dose were predictive of CPN. Particle density was only predictive of CPN in tumors treated with SA< 570 Bq. There were no independent predictors of CPN in tumors treated using SA≥ 570 Bq. CPN was achieved in 88% of tumors that met all treatment thresholds and in none that did not meet any threshold.