RecruitingFeasibility of Serial Multisite Image-guided Biopsy to Study Breast Cancer EvolutionFORTITUDE is a translational research study that aims to collect serial multi-site needle biopsy samples of tumour tissue and blood from metastatic breast cancer patients. Cancer biopsies are generally performed when cancer is diagnosed and are sometimes repeated when the cancer is suspected to have spread but this is not mandatory. However, studies have shown that cancers change with time and evolve to become resistant to therapy. The purpose of this study is to assess the feasibility of biopsies of multiple cancer sites across different time points during treatment and understand how cancers evolve and change throughout treatment. The findings of this study could pave the way for using cancer biopsies more frequently in the clinic to pick up changes in cancer behaviour that could influence treatment choice. The samples collected from this study will be used for molecular and genetic research to increase our understanding of how metastatic breast cancer changes during treatment and will enable us to develop new cancer treatments and new ways of monitoring response to cancer therapies.