Breast cancer stages

Breast cancer stages indicate how far cancer has spread within the breast, to nearby tissues, and to other organs. This information is obtained from the lymph node biopsy and other tests such as blood tests, bone scans, and X-rays. The stage of the cancer is a measurement of the extent of the disease when it is first diagnosed.¹

The stage of a cancer is one of the most important factors in selecting treatment options. It is the most significant, but not the only, factor in predicting your chances of being a long-term cancer survivor (prognosis). Each person's outlook differs depending on the stage of the cancer, the particular treatment, and the person's general state of health. Talk to your health professional about your own prognosis.²

Stage 0 (Tis)

Early cancer is confined to the breast (noninvasive or in situ breast cancer), such as:

• Ductal carcinoma in situ (DCIS). Cancer cells are located within a duct but are not found in surrounding fatty breast tissue.
• A form of DCIS that only involves the nipple (Paget's disease of the breast).
• Lobular carcinoma in situ (LCIS). Abnormal cells grow within the lobules (milk-producing glands) but do not penetrate through the lobule walls. Most breast specialists do not consider LCIS a true breast cancer. LCIS is also called lobular neoplasia.

Stage I

Tumor measures 2cm or smaller in diameter and has not spread to lymph nodes in the armpit.

Stage II

Stage II is divided into substages known as IIA and IIB.

• Stage IIA: Either of the following characteristics is true of this stage of breast cancer:
  • The tumor is smaller than 2cm in diameter and has spread to 1 to 3 lymph nodes under the arm on the same side as the breast cancer. Lymph nodes are not stuck to one another or to the surrounding tissues.
  • The tumor is larger than 2cm but smaller than 5cm in diameter and has not spread to the lymph nodes under the arm.
• Stage IIB: Either of the following characteristics is true of this stage of breast cancer:
  • The tumor is larger than 2cm but smaller than 5cm in diameter and has spread to 1 to 3 lymph nodes under the arm on the same side as the breast cancer. Lymph nodes are not stuck to one another or to the surrounding tissues.
  • The tumor is larger than 5cm in diameter but has not spread to the lymph nodes under the arm.

Stage III

Stage III is divided into substages known as IIIA, IIIB, and IIIC.

• Stage IIIA: Either the tumor or tumors measure larger than 5cm in diameter with any spread to lymph nodes; it is smaller than 5cm but the lymph nodes are stuck to one another or surrounding tissue; or it has spread to 4 to 9 lymph nodes.
• Stage IIIB: Breast cancers of any size have spread to the skin or chest wall.
• Stage IIIC: Breast cancers of any size have one of the following characteristics:
  • Breast cancer cells have spread to 10 or more lymph nodes under the arm.
  • Breast cancer cells are found in the lymph nodes under the arm and beneath the breast bone (internal mammary nodes).
  • Breast cancer cells are found in the lymph nodes above the collarbone (supraclavicular) or below the collarbone (infraclavicular).

Stage IV

Cancer of any size has spread (metastasized) to distant sites, such as the bones or lungs, or to lymph nodes not near the breast.

Citations

1. Singletary SE, et al. (2002). Revision of the American Joint Committee on Cancer Staging System for Breast Cancer. Journal of Clinical Oncology, 20(17): 3628–3636.

2. Bunnell CA, et al. (2003). Breast cancer: Staging and prognosis. In B Furie et al., eds., Clinical Hematology and Oncology, pp. 715-725. Philadelphia: Churchill Livingstone.

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