Relationship of Radiation Dose to Efficacy of Radioembolization of Liver Metastasis from Breast Cancer

PURPOSE: To determine the relationship of tumoral and nontumoral radiation dose to response and toxicity after transarterial radioembolization (TARE) of breast cancer liver metastasis. METHODS: This retrospective study evaluated all patients with breast cancer liver metastases treated with TARE (2/2011—6/2019). Extent of disease was measured as unilobar or bilobar on baseline PET/CT prior to TARE. Response was assessed for targeted regions with modified PERCIST criteria on first follow-up PET/CT. Tumoral and nontumoral liver dosimetry was evaluated by performing volumetric segmentation on post-TARE Bremsstrahlung SPECT/CT. ≥Grade 3 hepatotoxicity was defined as ≥grade 3 bilirubin/AST/ALT elevation or ascites requiring intervention. Fisher’s exact tests, Wilcoxon rank sum tests, and Kaplan-Meier survival analysis were performed. RESULTS: Among 64 women, 60 patients had pre- and post-TARE PET/CT, of whom 46/60 (77%) achieved objective response (OR). Responders received higher tumoral dose with a median (interquartile range) of 167 (96(—)217) vs. 54 (45(—)62) Gy (p79.5 Gy) was associated with OR, which was associated with longer survival. Pre-existing liver dysfunction was associated with hepatotoxicity, which was associated with decreased survival.