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Staging is a way to describe the size of the cancer and whether it has spread. Your breast cancer's stage helps your healthcare team understand your prognosis. It also helps your team create a treatment plan that fits your cancer.

Breast cancer stages range from 0 to 4. A lower number means the cancer is less advanced and more likely to be cured. As the cancer grows and gets more advanced, the stages get higher. A stage 4 breast cancer means that the cancer has spread to other parts of the body.

Staging information

To stage the breast cancer, the healthcare team collects as much information about the cancer as possible. The information comes from the exams and imaging tests you've had, as well as the biopsy report from the pathologist.

Information used in staging includes:

• The size of the cancer in the breast.
• Whether cancer cells have spread to the lymph nodes or other parts of the body.
• The cancer's grade.
• The cancer's hormone receptor status.
• The cancer's HER2 status.
• The presence of certain genes that might impact treatment options.
• Other pieces of information that may become available after the cancer is removed during surgery.

Types of staging

The process of breast cancer staging can take place at different times after diagnosis and around treatment. Your stage may change as your care team gets more information about your cancer.

Healthcare professionals use different types of stages at different times.

• Anatomic staging happens after a breast biopsy confirms cancer. It tells your care team about the size of the cancer and whether it has spread. It does not take cancer grade, hormone receptor status or HER2 status into account.
• Clinical prognostic staging happens after all tests on your biopsy sample are complete and your care team knows your cancer grade, hormone receptor status and HER2 status. The prognostic staging process tells your care team more about how well medical treatment works against the cancer. It helps the team choose the first treatment.
• Pathological prognostic staging is used after surgery once the cancer is removed. This kind of staging looks at factors such as the size of the cancer removed during surgery and the number of lymph nodes removed that contain cancer.
• Postneoadjuvant therapy prognostic staging is used when you receive medicine as your first treatment for breast cancer. This staging process considers the status of the cancer after the medicine is given. It can help your care team decide what to do next.

Because there are several types of stages that consider different factors, the stages of breast cancer can be confusing and complicated. Ask your healthcare team to explain your stage and what it means for your treatment.

Anatomic stages

Anatomic staging is the simplest form of breast cancer staging. To decide on the anatomic stage, the healthcare team uses the size of the cancer and whether it has spread. Using this type of staging, the stages go from 0 to 4.

• Stage 0. Cancer cells have not grown beyond the ducts. This cancer does not spread. Ductal carcinoma in situ is a stage 0 noninvasive cancer.
• Stage 1. The cancer in the breast is less than 1 inch (2 centimeters) in diameter. Cancer cells have spread beyond the ducts into the breast tissue. There is little or no evidence of cancer in the lymph nodes. Cancer has not spread elsewhere in the body.
• Stage 2. The cancer in the breast is less than 2 inches (5 centimeters) in diameter and has spread to some underarm lymph nodes. Or the cancer is larger than 2 centimeters in diameter and has not spread to the underarm lymph nodes.
• Stage 3. The cancer in the breast is any size and has spread to many underarm lymph nodes. Or the cancer is larger than 2 inches (5 centimeters) in diameter and has spread to some underarm lymph nodes. This stage also includes cancers that spread to the skin, the chest beyond the muscle, or the lymph nodes inside the chest wall. Inflammatory breast cancer is considered a stage 3 cancer.
• Stage 4. The cancer in the breast is any size and cancer cells have spread to sites away from the breast and nearby lymph nodes. These sites may include the brain, bones, lungs or liver.

The anatomic stage may be the first stage your healthcare team talks about after your diagnosis. The stage may change as your team gets more information about your cancer, such as the hormone receptor status.

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