Breast cancer begins when abnormal cancerous cells in the breast grow and multiply without stopping, creating a tumor. Breast cancer usually starts in the ducts or lobules of the breast.
"Advanced breast cancer" usually refers to metastatic breast cancer, also called Stage IV breast cancer. Breast cancer that has spread locally in the area of the breast, but not to distant organs and tissues, is often referred to as "locally advanced breast cancer," or Stage III breast cancer. Given these various and sometimes inconsistent terms, if you or a loved one is diagnosed with advanced breast cancer, it's important to discuss with your doctor specifically what stage it is and its other characteristics (eg, hormone receptor status and where the cancer has spread). Knowing these details of a diagnosis can help you make important treatment decisions.
Although this website refers to the two stages collectively as "advanced breast cancer," it is important to note that not all health professionals use the term consistently. "Advanced cancer" in general often means that the cancer is "metastatic" ie, has spread from where it started to distant parts of the body.
Advanced breast cancer is usually treated with systemic therapy (drugs that travel through the bloodstream, reaching and affecting cells in the body). Systemic therapy includes hormonal treatment, chemotherapy, and targeted therapy. You can learn more about treatment here.
Breast cancer is divided into five main stages, 0 through IV. The stages are based on the size of the tumor, the number of lymph nodes involved, and how much the cancer has spread. When breast cancer spreads or becomes worse, this is known as progression. In early stages of breast cancer, patients may receive surgery, radiation, or adjuvant treatment. By definition, adjuvant therapy is any treatment that follows primary treatment. For example, chemotherapy used to kill cancer cells that may be left behind after surgery and/or radiation is considered an adjuvant treatment.
The American Joint Committee on Cancer (AJCC) has developed a widely used system to stage breast cancer. Using this system, Stages 0, I, and II are early forms of the disease.
Advanced breast cancer includes the most serious of the five possible stages, Stages III and IV. Stage III is locally advanced breast cancer, which means the cancer has either extensively spread to lymph nodes and/or other tissue in the area of the breast, but not to distant sites in the body. Stage IV is metastatic breast cancer. At this stage, the cancer has spread to distant sites of the body, such as the liver, lungs, bones, brain, and/or other sites.
Metastasis means the spread of cancer to other parts of the body. Cancer cells can break away from a primary tumor and enter the bloodstream or lymphatic system (the system that produces, stores, and carries the cells that fight infections). This is how cancer cells spread to other parts of the body.
When cancer cells spread and form a new tumor in a different organ, the new tumor is a metastatic tumor. The cells in the metastatic tumor come from the original tumor. This means, for example, that if breast cancer spreads to the lungs, the metastatic tumor in the lung is made up of cancerous breast cells (not lung cells). In this case, the disease in the lungs is metastatic breast cancer (not lung cancer).
The most common sites of metastasis from solid breast cancer tumors are the lungs, bones, and liver. However, cancer can spread to other parts of the body as well.
Under a microscope, metastatic breast cancer cells generally look the same as the cancer cells in the breast, so you should consult an oncologist who specializes in the treatment of breast cancer regardless of where the cancer has spread.
To determine whether a tumor is primary or metastatic, a pathologist (a doctor who identifies diseases by studying cells and tissues under a microscope) examines a sample of the tumor. In general, cancer cells look like abnormal versions of cells in the tissue where the cancer first appeared. Using specialized diagnostic tests, a pathologist is often able to tell where the cancer cells came from.
Doctors may determine the primary site of cancer in a few ways. They may look for markers, which are a diagnostic indication that disease may develop. They may also look for antigens, a substance that causes the immune system to have a specific immune response.
Metastatic cancer may be found before or at the same time as the primary tumor, or months or years later. When a new tumor is found in a patient who has been treated for cancer in the past, it is often a metastasis versus another primary tumor.
Some people with metastatic cancer do not have symptoms. Their metastases may be found by X-rays and other tests. These tests include magnetic resonance imaging (MRI), computed tomography (CT scan), and positron emission tomography (PET scan), which may be performed for other reasons.
When symptoms of metastatic cancer occur, the type and frequency of the symptoms will depend on the size and location of the metastasis. For example, cancer that spreads to the bones is likely to cause pain and can lead to bone fractures. Shortness of breath may be a sign of lung involvement. Abdominal swelling or jaundice (yellowing of the skin) can indicate that cancer has spread to the liver.
Sometimes a person's primary cancer is discovered only after the metastatic tumor causes symptoms.
For additional information on breast cancer terminology, please visit Cancer.org glossary.
Almost everyone who has had cancer fears that one day the cancer will come back, or recur. The following sites help explain what is happening when someone has a recurrence, how you are likely to feel about it, and how you might approach the challenge ahead.