What are the stages of breast cancer?

There are several stages of breast cancer, depending on the severity of a diagnosis, but what does each one mean for those affected?

Here’s an overview of numbers and specifics for each stage of breast cancer, according to cancer.net.

Stage 0

This describes disease that is only in the ducts of the breast tissue and has not spread to the surrounding tissue of the breast. It is also called non-invasive cancer.

Stage IA

The tumor is small, invasive and has not spread to the lymph nodes.

Stage IB

Cancer has spread to the lymph nodes and the cancer in the lymph node is larger than 0.2 millimeters, but less than 2 millimeters in size. There is either no evidence of a tumor in the breast or the tumor in the breast is 20 millimeters or smaller.

Stage IIA

• There is no evidence of a tumor in the breast, but the cancer has spread to one to three auxiliary lymph nodes. It has not spread to distant parts of the body.
• The tumor is 20 millimeters or smaller and has spread to the auxiliary lymph nodes.
• The tumor is larger than 20 millimeters but not larger than 50 millimeters and has not spread to the auxiliary lymph nodes.

Stage IIB

This stage has one of two conditions:

• The tumor is larger than 20 millimeters but not larger than 50 millimeters and has spread to one to three auxiliary lymph nodes.
• The tumor is larger than 50 millimeters but has not spread to the auxiliary lymph nodes.

Stage IIIA

The cancer of any size has spread to four to nine auxiliary lymph nodes or to internal mammary lymph nodes. It has not spread to other parts of the body. There also might be a tumor larger than 50 millimeters that has spread to one to three auxiliary lymph nodes.

Stage IIIB

The tumor has spread to the chest wall or caused swelling or ulceration of the breast or is diagnosed as inflammatory breast cancer. It may or may not have spread to up to nine auxiliary or internal mammary lymph nodes. It has not spread to other parts of the body.

Stage IIIC

A tumor of any size that has spread to 10 or more auxiliary lymph nodes, the internal mammary lymph nodes and/or the lymph nodes under the collarbone. It has not spread to other parts of the body.

Stage IV (metastatic)

The tumor can be any size and has spread to other organs, such as the bones, lungs, brain, liver, distant lymph nodes or chest wall. Metastatic cancer found when the cancer is first diagnosed occurs about 6% of the time. This may be called de novo metastatic breast cancer. Most commonly, metastatic breast cancer is found after a previous diagnosis of early breast cancer.

This story was first published in 2019. It has since been updated.