Number stages of breast cancer

There are 4 number stages of breast cancer. Staging takes into account various factors, such as the size of the tumour, whether cancer cells have spread into the nearby lymph glands (lymph nodes), and whether the tumour has spread to any other part of the body. The word tumour means either a breast lump or the area of cancer cells found on a scan or mammogram.

The tests and scans you have when diagnosing your cancer give some information about the stage. The stage is important because it helps your breast cancer specialist to decide on the best treatment for you. Doctors usually make decisions about treatment for breast cancer according to the TNM stage, the grade of the cancer, and whether the cancer cells have receptors for hormones or biological therapy drugs. 

Doctors sometimes use a formula called the Nottingham Prognostic Indicator (NPI) to give some idea of how well treatment may work for an individual person with breast cancer and how long the person may live. You can read more about the Nottingham Prognostic Index (NPI) in this section. Doctors often also use computer programs such as Adjuvant Online, which use staging information as well as combined results of clinical trials, to help them decide which treatments may work best for individual people.

Below is a description of the breast cancer number staging system.

• The tumour is no more than 2 centimetres (cm) across (T1)
• There are no cancer cells in the lymph nodes in the armpit
• The cancer has not spread anywhere else

This is divided into two groups

Stage 2A means

• The tumour is less than 2 cm, the lymph nodes under the arm contain cancer but are not stuck to each other and the cancer has not spread or
• The tumour is less than 5 cm, there are no cancer cells in the lymph nodes in the armpit and the cancer has not spread or
• Although no tumour is seen in the breast, the lymph nodes under the arm contain cancer cells but are not stuck together or to other structures, and there is no sign of spread to other parts of the body

Stage 2B means

• The tumour is less than 5 cm and the lymph nodes under the arm contain cancer cells but are not stuck to each other, and the cancer has not spread or
• The tumour is bigger than 5 cm across, there are no cancer cells in the lymph nodes in the armpit and the cancer has not spread

Stage 3 breast cancer is divided into 3 groups

Stage 3A means

• Although no tumour is seen in the breast, the lymph nodes under the arm contain cancer cells and are stuck together or to other structures, but there is no sign of cancer spread or
• The tumour is 5 cm or less, the lymph nodes in the armpit contain cancer cells and are stuck to each other, but the cancer has not spread elsewhere or
• The tumour is more than 5 cm, the lymph nodes in the armpit contain cancer cells and may be stuck together, but there is no further spread

Stage 3B means

• The tumour is fixed to the skin or chest wall, the lymph nodes may or may not contain cancer cells, but there is no further spread

Stage 3C means

• The tumour can be any size and has spread to lymph nodes in the armpit and under the breast bone, or to nodes above or below the collarbone, but there is no further spread

In stage 4 breast cancer

• The tumour can be any size
• The lymph nodes may or may not contain cancer cells
• The cancer has spread (metastasised) to other parts of the body such as the lungs, liver or bones

If you have cancer cells in the breast and the lymph nodes in your armpit on the same side of the body, you do not have stage 4 breast cancer. Stage 4 only applies if the cancer has spread to other body organs.

If you would like more information about anything to do with the stages of breast cancer, you can contact one of the breast cancer organisations. You can find information about the TNM staging of breast cancer in this CancerHelp UK section. And general information about staging cancers in our about cancer section. You can also contact our cancer information nurses for more help.