MBC stands for Metastatic Breast Cancer, which is also known as stage IV or advanced breast cancer. It is a type of cancer that starts in the breast tissue and then spreads to other parts of the body, such as the bones, lungs, liver, or brain. When cancer is metastatic, it has traveled away from the breast and lymph nodes to other parts of the body. MBC is the most advanced stage of breast cancer, and the risk of MBC varies from person to person. Treatment decisions for MBC are based on specific disease characteristics, including MBC subtypes, which have specific receptors that can tell the cancer to grow, such as the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu)