Patient acquisition and data collection All patient should be female. All following demographic, clinical and tumour specific data will be collected: patient age, performance status according to the WHO classification at the time of first presentation to the hospital, stage, type and receptor status (ER, PR, HER-2) of the primary tumour, tumor load in the lung and/or liver (uni-or bilateral affection, number of metastases, diameter of the largest tumour size), chronology of the metastases (metachronous or synchronous), presence of further metastatic (synchronous metastases) or recurrent (metachronous) extrahepatic tumour growth and lymph node involvement in the mediastinal region or hepatoduodenal ligament. In addition, treatment-related and follow-up data will be documented: Intervention method (surgical resection, cryosurgery, laser-induced thermotherapy, radio-frequency ablation, ethanol injection, cyber-knife), median follow-up, incidence of tumour recurrence, time to recurrence, overall survival, and the administration of chemotherapy. Survival will be calculated from the date of diagnosis of the lung and/or liver metastases.