Metastatic breast cancer (stage 4 breast cancer) is when breast cancer has spread from the breasts or lymph nodes under the arms to other parts of the body, most often the bones, lungs and liver. It is not curable, but treatment may ease your symptoms and help you live longer. It can start months or even years after you finish treatment for an earlier-stage breast cancer that did not spread. This is also called a distant recurrence.
It’s not clear what causes breast cancer to spread to other areas of the body, but it probably happens when cancer cells break away from the original tumor and travel through the bloodstream or lymphatic system (a network of channels, nodes and glands that help your body fight disease). This enables them to reach other organs where they grow and form new tumors.
Most metastatic breast cancer spreads to the bones, lungs, liver or brain. If cancer has spread to the bones, you may have a pain in the bone that gets worse when you move or get up from bed. In some cases, this type of breast cancer can cause a fracture of the bone. Cancer that spreads to the lungs can lead to shortness of breath and coughing that won’t go away. A chest x-ray can show if cancer has spread to the lungs. In addition to a blood test, your doctor can use a special imaging test, such as a bone scan or a CT scan, to find out where the cancer is located. These tests look for “hot spots” that may indicate cancer, and they use a low dose of radiation to protect the surrounding healthy tissue.
If breast cancer spreads to the liver, you may have weight loss, fatigue or a swollen abdomen (ascites). Liver metastases can also lead to jaundice, itching or vomiting and a swollen belly (ascites). If cancer spreads to the brain, you may experience headaches, balance problems, weakness, numbness or vision changes.
Your doctor will ask you about your past health, symptoms and family history. He or she will do a physical exam and order lab tests to see how your liver, lungs and heart are working. Your doctor may also do a CT or an MRI to see if there is any damage in the lungs or liver and to check for any brain abnormalities. In some cases, your doctor may also do a “tap” — such as a pleural or spinal tap — to remove fluid from an area where you have symptoms. This allows your doctor to look at the fluid under a microscope and take a small sample of tissue for biopsy. Your doctor will explain the results of all these tests. He or she will discuss your options for treatment.
