Your doctor can give a detailed description of the state of your breast cancer by determining its stage. Staging summarizes important information also referenced in your pathology report, including tumor size, lymph-node status and cancer spread. Your doctor will use the stage of your cancer to choose the best treatment options for you.

The State of Your Cancer: Staging

There are five main stages of breast cancer:

• Stage 0: This cancer has not spread outside of the breast ducts or lobes where it started—it is non-invasive or “in situ.” Learn more about these terms in Breast Cancer Types.
• Stage 1 or I:  This cancer has a 2 cm or smaller tumor and has not spread to the lymph nodes.
• Stage 2a or IIa: Three different conditions can qualify as this type of cancer:
• No cancer exists in the breast, but it has reached the axillary lymph nodes (those under the arm).
• OR the tumor measures 2 cm or less, and cancer also exists in the axillary lymph nodes.
• OR the tumor measures 2-5 cm, but cancer cells have not entered the lymph nodes.
• Stage 2b or IIb: Two conditions qualify as this type of cancer:
• The tumor measures 2–5 cm and has spread to the axillary lymph nodes.
• OR the tumor measures more than 5 cm but has not spread to the lymph nodes.
• Stage 3a or IIIa: Two conditions qualify as this type of cancer:
• No tumor exists in the breast; cancer is found in lymph nodes near the breastbone or in axillary lymph nodes that are sticking together or to other structures.
• OR the tumor is any size. Cancer has spread to the lymph nodes near the breastbone or the axillary lymph nodes, which are sticking together or to other structures.
• Stage 3b or IIIb: This type of cancer has two features:
• A tumor of any size has spread to the chest wall or skin of the breast.
• AND cancer cells may have spread to lymph nodes near the breastbone or to axillary lymph nodes that are clumped together or sticking to other structures.
• Stage 3c or IIIc: This type of cancer has two features:
• No sign of cancer in the breast or a tumor of any size that has spread to the chest wall or the skin of the breast.
• AND the cancer has spread to lymph nodes either above or below the collarbone; the cancer may also have spread to axillary lymph nodes or to lymph nodes near the breastbone.
• Stage 4 or IV: The cancer has spread to other parts of the body, becoming metastatic. Learn more about this and other Breast Cancer Types.

More Information

Breastcancer.org

National Cancer Institute

General Staging Information (American Cancer Society)