Determination of Tumor Dose Response Thresholds in Patients with Chemorefractory Intrahepatic Cholangiocarcinoma Treated with Resin and Glass-based Y90 Radioembolization.

Abstract

To compare the efficacies of glass and resin-based Yttrium-90 microspheres by comparing absorbed tumor dose (TD) with both tumor response (TR) and overall survival (OS) in patients with chemorefractory intrahepatic cholangiocarcinoma (ICC). Post-Y90 treatment bremsstrahlung SPECT/CT of 38 consecutive patients receiving 45 treatments (21 resin microspheres, 24 glass microspheres) were analyzed retrospectively. MIM software v6.9.4 (MIM Software Inc, Cleveland, OH) was used to calculate targeted tumors' dose volume histogram. Modified Response Evaluation Criteria in Solid Tumors was used to evaluate tumor response 3months post-treatment. Kaplan Meier estimation was used for survival analysis. T-test was used to compare the devices on various dosimetric parameters. Thresholds for TD to predict TR with ≥ 80% specificity were as follows: mean TD (Resin: 78.9Gy; Glass: 254.7Gy), maximum TD (Resin: 162.9Gy; Glass: 591Gy), minimum TD (Resin: 53.7Gy; Glass: 149.1Gy). Microsphere type had no effect on survival from first Y90 (Resin: 11.2 mo; Glass 10.9 mo [p = 0.548]). In patients receiving resin microspheres, mean TD ≥ 75Gy or maximum TD ≥ 150Gy was associated with median OS of 20.2 mo compared to 6.5 mo for those receiving less (p = 0.001, 0.002, respectively). For patients treated with glass microspheres, those receiving a mean TD ≥ 150Gy had a median OS of 14.6 mo vs. 2.6 mo for those receiving less (p = 0.031). TD thresholds predictive of TR and OS differ significantly between glass and resin microspheres. However, microsphere type has no impact on survival in patients with chemorefractory ICC. Level 3, Retrospective Study.