Improved survival in patients with isolated liver metastasis at initial diagnosis with surgery at primary and metastatic sites: A population‐based study in patients with breast cancer

BACKGROUND: The aim of this study was to investigate epidemiological characteristics, risk factors, optimal treatment options, and survival outcomes of breast cancer patients with isolated liver metastasis (BCILM). METHODS: Patients with breast cancer (BC) were selected from Incidence‐Surveillance, Epidemiology, and End Results (SEER) Research Plus Data, 17 registries between 2010 and 2019. The Kaplan–Meier method and log‐rank test were used to compare survival rates between patients who received or did not receive surgery for the primary and liver metastatic sites. Univariate and multivariate analyses were conducted using Cox regression analysis. RESULTS: This study included 17 743 stage IV BC patients, with 3604 (20.3%) patients experiencing liver metastasis at initial diagnosis. Of 3604 liver metastasis patients, 951 were diagnosed with BCILM. The median survival time of patients with BCILM who underwent surgery at the primary site (52.0 months) or distant sites (85.0 months) was significantly longer than that of patients who did not undergo surgery at the primary site (23.0 months) or distant sites (32.0 months). Univariate analysis indicated that age, race, histological grade, molecular subtype, T stage, N stage, surgery of the primary site, surgery to other regional/distant sites, radiotherapy, and chemotherapy were prognostic factors affecting the overall survival (OS) and cancer‐specific survival (CSS) of patients with BCILM (p < 0.05). Multivariate analysis suggested that age, race, molecular subtype, T stage, surgery of the primary site, radiotherapy, and chemotherapy were independent prognostic factors. In the BCILM cohort, HR(+)/HER2(+) patients exhibited the best OS and CSS, followed by HR(−)/HER2(+), HR(+)/HER2(−), and HR(−)/HER2(−) patients (p < 0.0001; p < 0.0001). CONCLUSION: Surgery at the primary and metastatic sites was associated with better survival in patients with BCILM. HER2(+) patients with BCILM had a significantly better prognosis than HER2(−) patients.