Breast cancer stages reflect the size of the tumor, whether or not it is invasive (meaning it has "invaded" nearby breast tissue), whether it has reached the lymph nodes (glands that are part of the body's immune system), and whether it has spread to other parts of the body.
All breast cancers are assigned a stage based on biopsy results, as well as other findings from blood tests and imaging scans. Knowing the stage of breast cancer helps a patient and her (or his!) medical team make decisions about appropriate treatment. Breast cancer stages also help patients understand their chances of survival.
Here are the five breast cancer stages and the typical treatments for each.
At stage 4, breast cancer has spread, or metastasized, to distant sites in the body, often the bones, liver, brain, or lungs. This is called metastatic breast cancer. Although stage 4 breast cancer is considered incurable, new treatments are enabling patients to live longer with advanced-stage disease.
Drugs are the main treatment for stage 4 breast cancer. Chemotherapy is typically recommended. Women whose breast cancers are hormone receptor-positive, meaning they're fueled by female hormones, may take hormone therapy like Tamoxifen or an aromatase inhibitor to prevent their cancers from continuing to grow. Drugs that target specific characteristics of cancer cells, called targeted therapy, may block the effects of enzymes or proteins that promote cancer cell growth. Less often, surgery and radiation are used to alleviate symptoms, like if a breast cancer tumor is causing pain.
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Stage 3 breast cancer
Stage 3 breast cancer is an advanced cancer. It has spread to the lymph nodes but not to other organs. This stage is divided into three categories–3A, 3B, and 3C–based on tumor size and lymph node involvement.
Any of the following can qualify as a stage 3A cancer, according to the National Cancer Institute:
Either no tumor or a tumor of any size and cancer in four to nine nearby lymph nodes
A tumor larger than 5 centimeters across (about 2 inches) and small clusters of breast cancer cells in the lymph nodes
A tumor larger than 5 centimeters and cancer in one to three lymph nodes near the breastbone.
A stage 3B cancer can be any size. The cancer is in the chest wall or the skin of the breast, which can cause swelling. It has spread to up to nine nearby lymph nodes.
At stage 3C, there may be a tumor of any size, or no tumor, and either:
Cancer in 10 or more lymph nodes under the arm
Cancer in the lymph nodes near the collarbone
Cancer in the lymph nodes under the arm and near the breastbone
Stage 3 treatments vary widely. Some people require surgery–either the removal of the entire breast, called a mastectomy, or a breast-conserving surgery called a lumpectomy–and radiation, plus chemotherapy and lymph node removal. Patients may have hormone treatment or targeted cancer therapy.
Other patients may undergo chemo first to shrink the tumor, followed by mastectomy and radiation. Hormone therapy and targeted cancer therapies may be used when appropriate. People with stage 3 breast cancer will usually have surgery to remove at least some of the lymph nodes under the arm and may have radiation to treat lymph nodes near the collarbone and breastbone.
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Stage 2 breast cancer
At stage 2, breast cancer is growing but still in an early stage. This stage has two categories. At stage 2A, there may be one of the following:
No tumor and fewer than four lymph nodes with cancer under the arm
A small tumor (no more than 2 centimeters, or roughly 3/4 of an inch), with cancer in fewer than four underarm lymph nodes
A tumor of 2 to 5 centimeters but no lymph node involvement
Stage 2B breast cancer can involve:
A tumor of 2 to 5 centimeters and small clusters of breast cancer cells in the lymph nodes
A tumor between 2 and 5 centimeters and cancer in fewer than four lymph nodes under the arm
A tumor larger than 5 centimeters and no lymph node involvement
Although stage 2 breast cancers are larger than stage 1 tumors and may involve lymph nodes, they're still highly treatable. Options include mastectomy or lumpectomy (sometimes called a partial mastectomy), plus radiation and chemo. Hormonal treatments and targeted cancer therapies may be given if applicable. Lymph nodes will likely be biopsied or removed.
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Stage 1 breast cancer
Stage 1 breast cancer is invasive, meaning it has started spreading to healthy breast tissue. At stage 1A, the tumor is smaller than 2 centimeters across. It has not spread outside the breast, and no lymph nodes are involved.
At stage 1B, there's either no tumor, or the tumor is less than 2 centimeters, and small clusters of breast cancer cells are found in the lymph nodes.
At this stage, treatment usually involves a breast-conserving lumpectomy, followed by radiation. Chemotherapy may be recommended for stage 1 tumors bigger than 1 centimeter. A biopsy is generally done to look for cancer in nearby lymph nodes.
Also called pre-cancer, this is the earliest stage of breast cancer. The most common stage 0 cancer is ductal carcinoma in situ or DCIS, meaning the abnormal cell growth begins in the milk ducts of the breast.
Stage 0 breast cancer is not invasive, meaning it hasn't spread to other tissue in the breast. It could become invasive cancer in the future. Stage 0 cancer also has not spread to the lymph nodes or other parts of the body.
These cancers are usually treated with surgery alone or with radiation. Chemotherapy usually isn't required. People with DCIS fueled by estrogen or progesterone may receive hormone therapy after surgery to lower their risk of developing invasive breast cancer in the future. Some people with DCIS may not need any treatment.