Stage 4 cancer, also known as metastatic or advanced cancer, is the most severe stage of cancer. It means that the cancer has spread beyond its original location to other organs or distant parts of the body through the bloodstream or lymphatic system

. For example, breast cancer that spreads to the bones, lungs, liver, or brain is still considered breast cancer but at stage 4 due to metastasis

. Stage 4 cancer is typically not curable, but it is often treatable. Treatments aim to control the cancer's growth, relieve symptoms, and improve quality of life. Common treatments include systemic therapies such as chemotherapy, targeted therapy, immunotherapy, and sometimes surgery or radiation to manage symptoms

. Stage 4 cancer may have subcategories (like 4A, 4B, 4C) depending on how many distant sites are involved and whether certain areas, such as the lining of the abdomen, are affected

. In summary, stage 4 cancer indicates advanced disease with metastasis to other body parts, requiring systemic treatment approaches focused on prolonging life and managing symptoms rather than cure