Breast Cancer Stages: What Do They Mean?

After a breast cancer diagnosis, doctors give the cancer a stage from 0 to 4. The stage number describes whether the cancer has spread, and if so, where in the body it has spread.

• The size of the tumor
• Whether the cancer is in lymph nodes, and if so, how many lymph nodes are involved
• Whether the cancer has receptors for the hormones estrogen, progesterone, or both, and if it makes too much of a protein called human epidermal growth factor receptor 2 (HER2)

This information helps your doctor choose the right treatment for you. It can also give you an idea of what outlook to expect.

• Clinical staging is based on the results of a physical exam, imaging tests like mammogram and magnetic resonance imaging (MRI), and biopsy results.
• Pathologic staging is done with tissue removed during surgery. It’s based on the tumor size, features of the cancer, and lymph nodes involved.

The cancer stage starts with a number from 0 to 4. The higher the number, the farther the cancer has spread.

• T refers to the tumor’s size and whether it has grown into the skin or chest wall. It’s followed by a number from 0 to 4. The higher the number, the larger the tumor is and the more it has spread into tissues near the breast.
• N stands for “node.” It’s followed by a number from 0 to 3, which describes whether the cancer has spread to lymph nodes near the breast, and if so, how many nodes are involved. The higher the number, the more lymph nodes contain cancer. Once cancer is in the lymph nodes it can spread to other parts of the body.
• M means “metastasis.” It indicates whether the cancer has spread to distant organs like the bones, liver, brain, or lungs. M is followed by the number 0 or 1, where 0 means the cancer hasn’t spread and 1 means the cancer has reached other parts of the body.

• Grade: How much do the cancer cells look like healthy cells? High-grade cancers look more abnormal and tend to grow more quickly than low-grade ones.
• Estrogen receptor status: Do the cancer cells grow in response to the hormone estrogen?
• Progesterone receptor status: Do the cancer cells grow in response to the hormone progesterone?
• HER2 status: Do the cancer cells have too much of the HER2 protein, which makes them more aggressive?

Stage 0

Stage 0 breast cancer is only in the ducts — the tubes that carry milk to the nipple during breastfeeding. It hasn’t spread to surrounding tissues. Another name for cancer that hasn’t spread beyond the milk ducts is noninvasive breast cancer. Ductal carcinoma in situ (DCIS) is a type of noninvasive breast cancer.

Stage 1

• Stage 1A The cancer is 2 centimeters (cm) across or smaller and it has not spread into the lymph nodes or outside of the breast.
• Stage 1B Small clumps of cancer cells up to 2 millimeters (mm) in size are in the lymph nodes. There may not be a tumor in the breast, but if there is, it’s no bigger than 2 cm.

Stage 2

• Stage 2A There may be no tumor in the breast, or there is a tumor in the breast measuring 2 cm or less, and cancer has spread to up to three lymph nodes. Or, there’s a 2 to 5 cm tumor in the breast with no spread to lymph nodes.
• Stage 2B The tumor measures 2 to 5 cm and cancer has spread to up to three axillary lymph nodes or to lymph nodes near the breastbone. Or the tumor is bigger than 5 cm and it has not spread to the axillary lymph nodes.

Stage 3

• Stage 3A The tumor can be of any size, and the cancer has spread to four to nine axillary lymph nodes or to lymph nodes near the breastbone. Or the tumor is larger than 5 cm and small groups of cancer cells have reached the lymph nodes, or the cancer has spread to up to three axillary lymph nodes or to lymph nodes near the breastbone.
• Stage 3B The tumor can be any size and cancer has reached the skin of the breast or chest wall and caused swelling or a sore there. The cancer may have spread to up to nine axillary lymph nodes or to lymph nodes near the breastbone.
• Stage 3C The cancer may be any size and may have spread to the chest wall or breast skin, as in stage 3B. The cancer has spread to 10 or more axillary lymph nodes, to lymph nodes above or below the collarbone, or to axillary lymph nodes or lymph nodes near the breastbone.

Breast cancer that has not spread beyond the axillary lymph nodes (stages 0 through 2, and sometimes 3A) is also called early breast cancer.

Inflammatory breast cancer is always at least stage 3B. Symptoms of inflammatory breast cancer include breast redness, swelling, and warmth. Cancer cells have spread to the lymph nodes and may also be in the skin of the breast. Inflammatory breast cancer is a clinical diagnosis that starts with a physical exam and imaging tests, followed by a biopsy.

Stage 4

Doctors use imaging tests, biomarker tests, and biopsy results to stage breast cancer.

Imaging Tests

Mammogram The same test you get for breast cancer screening is also part of the diagnosis. A mammogram uses X-rays to take pictures of the inside of the breast. Doctors use mammography to determine how large the cancer is and where in the breast it’s located. This test can also show whether cancer is in lymph nodes near the breast.

Ultrasound This test uses sound waves to see inside your breasts. Your doctor can use ultrasound to confirm the diagnosis and find out where the cancer is in your breast.

Magnetic Resonance Imaging (MRI) An MRI uses powerful magnets and radio waves to create images of your breasts. This test can locate the cancer in the breast and measure the tumor size.

Computerized Tomography (CT) Scan This test takes many X-ray pictures of the breasts from different angles and combines them into a very detailed cross-sectional image. A CT scan is usually used for staging purposes, after a patient has already received a breast cancer diagnosis. For example, it can show whether the cancer has spread into the chest wall.

Positron Emission Tomography (PET) Scan A PET scan uses a radioactive tracer to find areas of cancer throughout the body.

Chest X-Ray This test can show whether the cancer has spread to the lungs.

Bone Scan This test can find breast cancer that has spread to the bones. A radioactive material injected into a vein collects in areas of the bone that contain cancer.

Biomarker Tests

Hormone receptor status: Does the cancer have receptors for the hormones estrogen, progesterone, or both?

HER2 status: Does the cancer make too much of the HER2 protein?

Tests for these biomarkers may sometimes be done to help stage the cancer and find the right treatment:

• Proteins like PD-L1 and Ki-67 that can affect the growth of cancer cells
• Gene mutations like BRCA1 and BRCA2 and PIK3CA
• Carcinoembryonic antigen (CEA), which shows whether the cancer has spread to other parts of the body.

Sentinel Node Biopsy

The breast cancer stage is one factor that goes into determining your prognosis. The lower the stage, the less the cancer has spread and, generally, the better the outlook.

• Localized (no cancer outside the breast): 99 percent
• Regional (the cancer has spread to nearby structures or to lymph nodes): 86 percent
• Distant (the cancer has spread to organs like the bones, liver, or lungs): 31 percent

• Cancer subtype (hormone receptor–positive, HER2-positive, etc.)
• Grade, or how different the cancer cells look from healthy cells
• Whether cancer has spread to the lymph nodes, and if so, how many lymph nodes are involved

The Takeaway

Staging is the way to determine whether breast cancer has spread, and if so, how far it has spread. Breast cancer is staged from 0 to 4. The cancer’s hormone status, genetic makeup, and grade also go into staging the cancer. Knowing the stage helps your doctor find the best treatment for your cancer and predict your outlook.

Early-stage breast cancers are considered very treatable and have high survival rates. At stage 4 the cancer isn’t curable, but it is still treatable. Thanks to treatment advances, people with metastatic breast cancer are living longer and having a higher quality of life.