Merck Manual

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Stages of Breast Cancer

Stages of Breast Cancer

Stage

Description

In situ carcinoma

0

The tumor is confined, usually to a milk duct or milk-producing gland, and has not invaded surrounding breast tissue, or Paget disease of the nipple with no lump is present.

Localized and regional invasive cancer

IA

The tumor is 2 centimeters (about 3/4 inch) or less in diameter and cancer cells have not spread beyond the breast.

IB

Lymph nodes near the breast contain microscopic amounts* of cancer cells plus one of the following:

  • The tumor is 2 centimeters or less in diameter.

  • There is no tumor in the breast.

IIA

The tumor is 2 centimeters or less in diameter or there is no tumor in the breast, and cancer cells have spread to one to three lymph nodes in the armpit or to the lymph nodes near the breastbone.

or

The tumor is larger than 2 centimeters but no larger than 5 centimeters (about 2 inches) in diameter, but cancer cells have not spread beyond the breast.

IIB

The tumor is larger than 2 centimeters but no larger than 5 centimeters in diameter, and cancer cells have spread to one to three lymph nodes in the armpit or to the lymph nodes near the breastbone.

or

The tumor is larger than 5 centimeters in diameter but has not spread beyond the breast.

IIIA

The tumor can be any size or there is no tumor, and cancer cells have spread to four to nine lymph nodes in the armpit, which are matted together or stuck to the skin or chest wall, or spread to lymph nodes near the breastbone on the same side as the tumor but not to those in the armpit.

or

The tumor is larger than 5 centimeters in diameter, and lymph nodes near the breast contain microscopic amounts* of cancer cells.

or

The tumor is larger than 5 centimeters in diameter and cancer cells have spread to one to three lymph nodes in the armpit or to the lymph nodes near the breastbone.

IIIB

The tumor can be any size, and cancer cells have spread to the chest wall and/or skin, and the breast is swollen or sores have formed on the breast. Also, cancer cells may have spread to up to nine lymph nodes in the armpit or to lymph nodes near the breastbone.

or

Inflammatory breast cancer is present.

IIIC

The tumor can be any size or there is no tumor plus at least one of the following:

  • It has spread to 10 or more lymph nodes in the armpit.

  • It has spread to lymph nodes in the armpit and near the breastbone.

  • It has spread to lymph nodes under or above the collar bone.

Cancer cells may have spread to the chest wall and/or skin or caused swelling or sores, or inflammatory breast cancer may be present.

Metastatic cancer

IV

The tumor, regardless of size, has spread to distant organs or tissues, such as the lungs or bones, or to lymph nodes distant from the breast.

*Microscopic amounts of cancer cells in lymph nodes are called micrometastases.