Metastatic Breast Cancer patients for Breast Cancer

Tissue biopsy is a procedure to remove a piece of tissue (sample of cells) from the body to be analyzed in a laboratory, and it is commonly performed to confirm diagnosis of a patient with symptoms of breast cancer recurrence. It may also provide information on tumor markers (hormone receptors, HER2) that can guide treatment decisions. The goal of this study is to determine whether blood tests (which require less-invasive procedures) can be used to confirm diagnosis of suspected recurrent breast cancer (as compared to tissue biopsy). Investigators plan to investigate blood factors which include circulating tumor cells (CTCs - i.e., cancer cells that can be detected in the blood), circulating tumor DNA (ctDNA - i.e., pieces of DNA from cancer cells that can be found in the blood), as well as other biomarkers. Investigators will conduct this study in 120 participants who present with suspected breast cancer recurrence and symptoms of cancer that has spread to other areas in the body. Participants will be asked for blood collection within 30 days before tissue biopsy. The tissue will be analysed locally to determine the presence of cancer and the tumor markers listed above. The blood will be processed and stored for analysis of CTCs and ctDNA. If these blood tests show concordance with tissue based tests (presence of cancer cells, hormone receptors \& HER2 status), these tests could be used in future studies to confirm diagnosis using a non-invasive procedure. Also, investigators believe that the results of this study can influence other research of early-stage recurrent breast cancer.