The liver represents the third most common site of breast cancer (BC) metastases behind the lymphatics and bone. The primary treatment for BCLM remains chemo-therapy and, more recently, targeted immunotherapy. The role of liver resection in BCLM remains controversial. The primary aim of the study is to compare the efficacy of liver resection vs. medical therapy alone in Breast Cancer Liver Metastasis (BCLM) patients.

In this multicenter observational ambispective study, will be enrolled all patients with BCLM underwent liver resection or medical treatment alone afferent to the Fondazione Policlinico Gemelli IRCSS of Rome (Italy), and other 8 International centers

The study foresees two distinct phases:

• I phase (only retrospective phase): it will cover all patients underwent to either medical treatment or surgery for which all data are available, with a follow up of 5 years at March 31, 2023. All patients data will be recovered from January 1994 till March 31, 2018. At the end of "phase I", is provided an "ad interim" analysis.
• II phase (ambispective): All patients retrieved from the archives between April 1, 2018 and the April 30, 2023 will be included, as well as all prospectively enrolled patients till December 31 2023, so that the last patient enrolled will end the 5-years follow-up phase within December 31, 2028.

The primary endpoint is to analyze the efficacy of liver surgery as compared to medical therapy alone in terms of 5-years overall survival in patients with breast cancer who underwent to liver resection or medical therapy alone.

The secondary endpoints are: recurrence rate; post-operative mortality (in patients who underwent to surgical treatment), post-operative complication (in patients who underwent to surgical treatment). And also: to assess potential predictive factors of 5-years overall survival in patients with breast cancer who underwent to either liver resection or medical therapy alone, to assess recurrence free survival (RFS) of liver surgery as compared to medical therapy alone in terms of 5-years overall survival in patients with breast cancer who underwent to liver resection or medical therapy alone and to assess potential predictive factors of 5-years RFS in patients with breast cancer who underwent to either liver resection or medical therapy alone.

Inclusion Criteria:

• > 18 years old
• BCLM
• BCLM and extra-hepatic disease
• Any treatment
• Ability to understand and sign the informed consent

Exclusion Criteria:

• Inability to provide the informed consent
• Patient who underwent Best Supportive Care or Palliation

All patient with BCLM underwent liver resection or medical treatment alone.