⁹⁰Y Radioembolization of Metastatic Breast Cancer to the Liver: Toxicity, Imaging Response, Survival

Purpose: To present data from patients with breast cancer liver metastases who underwent radioembolization with yttrium (⁹⁰Y) microspheres. Materials and Methods: Using standard ⁹⁰Y lobar treatment protocol, 27 female patients with progressing liver metastases on standard of care polychemotherapy were treated under an open-label phase 2 protocol. After treatment, we assessed (a) tumor response using computed tomography and/or positron emission tomography, (b) biochemical toxicity, and (c) survival. Results: The mean age of the patients was 52. Seventeen (63%) patients received 20 left lobe treatments (median radiation dose, 123 Gy; mean, 119 Gy), and 20 (74%) patients received 22 right lobe treatments (median radiation dose, 121 Gy; mean, 109 Gy) to the treatment site. No significant dose-difference was noted between the two lobes (P = .69). Tumor response on 90-day follow-up computed tomography showed (a) complete and partial response in nine (39.1%) patients, (b) stable disease in 12 (52.1%) patients, and (c) progressive disease in 2 (8.8%) patients. Positive tumor response on positron emission tomography was noted in 17 (63%) patients. Three of 27 (11%) patients (Eastern Cooperation Oncology Group 1, 2, or 3) showed bilirubin toxicity of grade 3, all of which were attributed to disease progression. Median survival for Eastern Cooperation Oncology Group 0 versus 1, 2, or 3 patients was 6.8 months and 2.6 months, respectively (P = .24) and for patients with tumor burden <25% versus >25% was 9.4 and 2.0 months, respectively (P = .46). Conclusions: Radioembolization with ⁹⁰Y brachytherapy device may be a viable therapeutic option for the treatment of breast cancer liver metastases in patients who have progressed or failed on standard of care polychemotherapy.