Our breast cancer doctors need to know the extent (stages) of the cancer in order to plan your breast cancer treatment. Breast cancer stages are based on the size of the tumor and whether the cancer has spread. Staging may include x-rays and lab tests. When breast cancer spreads, cancer cells are often found in lymph nodes under the arm. Sometimes the stage of cancer is not known until after surgery is performed to remove the tumor in your breast and the lymph nodes under your arm.

The stages of breast cancer are:

Stage 0
Stage I
Stage II
Stage III
Stage IV



Stage 0:  carcinoma in situ.

  • Lobular carcinoma in situ (LCIS): Abnormal cells appear in the lining of a lobule. LCIS rarely becomes invasive cancer, but, having LCIS in one breast can increase the risk of cancer for both breasts.
  • Ductal carcinoma in situ (DCIS): Abnormal cells appear in the lining of a duct. DCIS is also called intraductal carcinoma. Abnormal cells have not extended outside the duct. They have not penetrated the nearby breast tissue. If not treated, DCIS can become invasive cancer.
    This pictures shows ductal carcinoma in situ.


Stage I:  an early stage of invasive breast cancer. Cancer cells have not spread beyond the breast. The tumor is no more than 2 centimeters (three-quarters of an inch) across. This picture shows cancer cells spreading outside the duct.  The cancer cells are invading nearby tissue inside the breast.



Stage II:  can be one of the following:

  • The cancer has spread to the lymph nodes under the arm. The tumor is no more than 2 centimeters (three-quarters of an inch) across.
  • The cancer has not spread to the lymph nodes under the arm. The tumor is between 2 and 5 centimeters (three-quarters of an inch to 2 inches).
  • The cancer has spread to the lymph nodes under the arm. The tumor is between 2 and 5 centimeters (three-quarters of an inch to 2 inches).
  • The cancer has not spread to the lymph nodes under the arm. The tumor is larger than 5 centimeters (2 inches).


Stage III:  the cancer is locally advanced and is divided into Stage IIIA, IIIB, and IIIC.

  • Stage IIIA

The cancer has spread to underarm lymph nodes that are attached to each other or to other structures. Or the cancer may have spread to lymph nodes behind the breastbone. The tumor is no more than 5 centimeters (2 inches) across.

The cancer has spread to underarm lymph nodes that are either alone or attached to each other or to other structures. Or the cancer may have spread to lymph nodes behind the breastbone. The tumor is more than 5 centimeters across.

  • Stage IIIB

This stage is a tumor of any size that has grown into the chest wall or the skin of the breast.It may be coupled with swelling of the breast or with lumps in the breast skin.The cancer may have spread to lymph nodes under the arm.The cancer may have spread to underarm lymph nodes that are attached to each other or other structures.

  • Stage IIIC

This stage is a tumor of any size.The cancer has spread to the lymph nodes behind the breastbone and under the arm.The cancer has spread to the lymph nodes above or below the collarbone.



Stage IV:  is distant metastatic cancer. The cancer has spread to other parts of the body.