Important Stages and Prognosis of Breast Cancer

The stages of breast cancer are defined by the size of the tumor and whether or not cancer has spread or “metastasized”. The stage is determined through testing done on the tumor and lymph nodes after they are removed or during imaging tests performed prior to surgery. You can learn more about each stage below.

Stage 0

Also called carcinoma in situ, the cancerous cells are confined to the ducts, lobes, or nipples. No cancerous cells are present in the fatty tissue or the lymph nodes. This stage is also sometimes referred to as “pre-cancer”.

Stage 1A

Cancer has formed a tumor that is 2 centimeters or less in size. The cancer has not spread outside of the breast.

Stage 1B

Small clusters of breast cancer cells are found in the lymph nodes. In some cases, there is a small tumor. In other cases, there is no tumor in the breast.

Stage 2A

There are two different kinds of cases that may be classified as stage 2A. In one case, there is no tumor in the breast or the tumor is 2 centimeters or less in size, as it is in stage 1A, but cancerous cells have been found in at least 1, but not more than three of the lymph nodes. In the other case, the tumor is between 2 and 5 centimeters in size, but cancer has not spread to the lymph nodes.

Stage 2B

2B of the breast cancer stages is when the tumor is between 2 and 5 centimeters in size and it has spread to the lymph nodes, although only small clusters of cancerous cells, less than 2 millimeters in size are found in the lymph nodes. This classification is also used for tumors larger than 5 centimeters when cancer has not spread to the lymph nodes.

Stage 3A

This is one of the breast cancer stages in which cancerous cells are found in the lymph nodes. The tumor may be of any size. When the lymph nodes are involved, there is a greater risk that cancer will metastasize or spread to other parts of the body.

Stage 3B

In this stage, the lymph nodes are usually involved and cancer has spread to the chest wall and/or to the skin to cause an ulcer. If the skin is involved, it may be inflammatory breast cancer, a type in which the entire breast is painful, red, and enlarged.

Stage 3C

In this stage, cancer has spread even further, often involving the lymph nodes above or below the collarbone, as well as those under the arm and near the breastbone. The skin or chest wall may also be involved. Some stage IIIC cancers are inoperable, while others can still be treated with surgery.

Stage 4

Cancer has spread to other parts of the body via the lymph nodes and the bloodstream. The brain, lungs, liver and bones are most often affected. The prognosis is very poor at this stage.
What you should remember about these breast cancer stages is that any stage can progress to stage 4 without treatment. This is why early detection and early treatment are so important.

Each of the above stages has various sub-classifications that allow the treating surgeons and physicians to stage their patients more accurately. Recently, the staging system has been updated to include hormone receptors, HER 2 status, cancer grade, and genomic scores like Oncotype Dx.


A prognosis is an estimate of the likely outcome of a disease, based on the stages. It is just an estimate, and not an invariable truth. For cancer, the prognosis is expressed as a 5 or 10-year survival rate. This gives an idea of how many people are likely to be alive at 5 or 10 years after their diagnosis. In breast cancers localized to the breast, the 5-year relative survival rates can be as high as 95% or above. In women with locoregional disease, the 5-year survival rate drops to approximately 85%. In women with metastasis to distant organs, the 5-year survival rate is around 30%.

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