People with breast cancer are usually given a stage along with their diagnosis. The stage is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body.
Doctors use diagnostic tests to find out a cancer stage so information about staging may not be available until all the tests are finished. Knowing the stage will help your doctor decide which treatment plan will be most effective and help predict your prognosis.
Doctors assign the stage of breast cancer using a number zero (0) through 4 (Roman numerals I through IV). Doctors may refer to stage I and stage IIA cancer stage (early stage) and to stage IIB and stage III as “locally advanced.” Stage IV is called “metastatic breast cancer.”
Stage 0
The disease is only in the ducts and/or lobules of the breast and has not spread to the surrounding breast tissue. It is also called in situ or noninvasive cancer.
Stage IA
The tumor is small and invasive, but it has not spread to the lymph nodes.
Stage IB
A small number of cancer cells have spread to the axillary lymph nodes under the arm and formed tiny clusters larger than 0.2 mm but smaller than 2 mm in size. There is either no evidence of a tumor in the breast, or the tumor in the breast is 20 mm or smaller.
Stage IIA
This cancer stage has any of the following characteristics:
• There is no evidence of a tumor in the breast, but there is cancer in the axillary lymph nodes.
• The tumor is 20 mm or smaller and has spread to the axillary lymph nodes.
• The tumor is between 20 mm and 50 mm and has not spread to the axillary lymph nodes.
Stage IIB
The cancer has either of the following characteristics:
• The tumor is between 20 mm and 50 mm and has spread to 1 to 3 axillary lymph nodes.
• The tumor is larger than 50 mm but has not spread to the axillary lymph nodes.
Stage IIIA
The tumor may be any size, but it has spread to 4 to 9 axillary lymph nodes or to internal mammary lymph nodes. It has not spread to other parts of the body. Stage IIIA may also describe a tumor larger than 50 mm that has spread to small areas of cancer in the lymph nodes.
Stage IIIB
The tumor has spread to the chest wall, caused swelling or ulceration of the breast, or is diagnosed as inflammatory breast cancer. It may or may not have spread to the axillary or internal mammary lymph nodes under the arm. It has not spread to other parts of the body.
Stage IIIC
The tumor can be any size, but it has spread to 10 or more axillary lymph nodes, the internal mammary lymph nodes, and/or other lymph nodes under the collarbone. The cancer has not spread to other parts of the body.
Stage IV
The tumor can be any size, but the distinguishing characteristic is that it has spread to other distant sites in the body.
Recurrent
The breast cancer has come back after treatment.
