Number stages of breast cancer

There are 4 number stages of breast cancer. Staging takes into account various factors, including

• The size of the tumour (tumour means either a breast lump or the area of cancer cells found on a scan or mammogram)
• Whether cancer cells have spread into the nearby lymph glands (lymph nodes)
• Whether the tumour has spread to any other part of the body (metastasised)

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.

Stage 1 breast cancer is split into 2 stages

Stage 1A means that the tumour is 2cm or smaller and has not spread outside the breast

Stage 1B means that small areas of breast cancer cells are found in the lymph nodes close to the breast and either

• No tumour is found in the breast or
• The tumour is 2cm or smaller

This is divided into two groups

Stage 2A means

• There is no tumour or a tumour 2cm or smaller in the breast and cancer cells are found in 1 to 3 lymph nodes in the armpit or in the lymph nodes near the breastbone or
• The tumour is larger than 2cm but not larger than 5cm and there is no cancer in the lymph nodes

Stage 2B means

• The tumour is larger than 2cm but not larger than 5cm and small areas of cancer cells are in the lymph nodes or
• The tumour is larger than 2cm but not larger than 5cm and the cancer has spread to 1 to 3 lymph nodes in the armpit or to the lymph nodes near the breastbone or
• The tumour is larger than 5cm and has not spread to the lymph nodes

Stage 3 breast cancer is divided into 3 groups

Stage 3A means

• No tumour is seen in the breast or the tumour may be any size and cancer is found in 4 to 9 lymph glands under the arm or in the lymph glands near the breastbone or
• The tumour is larger than 5cm and small clusters of breast cancer cells are in the lymph nodes or
• The tumour is more than 5cm and has spread into up to 3 lymph nodes in the armpit or to the lymph nodes near the breastbone

Stage 3B means

The tumour has spread to the skin of the breast or to the chest wall, and made the skin break down (an ulcer) or caused swelling – the cancer may have spread to up to 9 lymph nodes in the armpit or to the lymph glands near the breastbone

Cancer that has spread to the skin of the breast may also be inflammatory breast cancer.

Stage 3C means

The tumour can be any size, or there may be no tumour, but there is cancer in the skin of the breast causing swelling or an ulcer and it has spread to the chest wall. It has also spread to 

• 10 or more lymph nodes in the armpit
• Lymph nodes above or below the collar bone
• Lymph nodes in the armpit and near the breastbone

For treatment, doctors divide stage 3C breast cancer into cancers that can be operated on (operable breast cancers) and those that can't (inoperable cancer).

Cancer that has spread to the skin of the breast may also be inflammatory breast cancer.

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 bones, lungs, liver orbrain

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