Selective internal radiation therapy of metastatic breast cancer to the liver: A meta-analysis

INTRODUCTION: The aim of this study is to conduct a meta-analysis to assess the efficacy of yttrium-90 selective internal radiation therapy (SIRT) in treating patients with breast cancer with hepatic metastasis. METHOD: PubMed and The Cochrane Library were queried from establishment to January 2021. The following keywords were implemented: “breast”, “yttrium”, and “radioembolization”. The following variables and outcomes were collected: publication year, region, sample size, study design, presence of extrahepatic disease, tumor burden, infused radioactivity, breast cancer subtype, previous treatment, median survival time (MST), length of follow-up, adverse events, and radiographical response such as Response Evaluation Criteria in Solid Tumors (RECIST), modified RECIST (mRECIST), and Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST). RESULTS: A total of 24 studies from 14 institutions were included in the present meta-analysis. On the basis of the data from 412 patients, post-embolization MST was 9.8 [95% confidence interval (CI): 9.0–11.6] months. Patients with additional extrahepatic metastasis had a poorer survival rate compared with those with localized hepatic metastasis only (MST: 5.3 vs. 15 months, p < 0.0001). Patients with <25% liver tumor burden exhibited more promising survival than those with >25% (MST: 10.5 vs. 6.8 months, p < 0.0139). On the basis of RECIST, mRECIST, and PERCIST criteria, tumor response rate was 36% (95% CI: 26%–47%), 49% (95% CI: 34%–65%), and 47% (95% CI: 17%–78%), respectively, whereas tumor control rate was 85% (95% CI: 76%–93%), 73% (95% CI: 59%–85%), and 97% (95% CI: 91%–100%), respectively. CONCLUSION: On the basis of the available published evidence, SIRT is feasible and effective in treating patients with breast cancer with liver metastasis. Patients with lower hepatic tumor burden and without extrahepatic metastasis demonstrated more survival benefit. Future randomized controlled trials are warranted.