Dose-response Analysis in Hepatic Tumors Treated with 90Y-TARE According to a Personalized Dosimetric Workflow: Preliminary Results

Background: Transarterial Radioembolization (TARE) is a widespread radiation therapy for unresectable hepatic lesions, but a clear understanding of the dose-response link is still missing. The aim of this preliminary study is to investigate the role of both dosimetric and clinical parameters as classifiers or predictors of response and survival for TARE in hepatic tumors and to present possible response cut-off. Methods: 20 patients treated with glass or resin microspheres according to a personalized workflow were included. Dosimetric parameters were extracted from personalized absorbed dose maps obtained from the convolution of 90Y PET images with 90Y voxel S-values. Results: D95 ≥ 104 Gy and tumor mean absorbed dose MADt ≥ 229 Gy were found to be optimal cut-off values for complete response, while D30 ≥ 180 Gy and MADt ≥ 117 Gy were selected as cut-off values for at least partial response and predicted better survival. Clinical parameters Alanine Transaminase (ALT) and Model for End-Stage Liver Disease (MELD) didn’t show sufficient classification capability for response or survival. Concusion: These preliminary results highlight the importance of an accurate dosimetric evaluation and suggest a cautious approach when considering clinical indicators. Dosimetric cut-off values could be a support tool in both planning and post-treatment phases. Larger multi-centric randomized trials, with standardized methods regarding patient selection, response criteria, Regions of Interest definition, dosimetric approach and activity planning are needed to confirm these promising results.