Stages of breast cancer

Your specialist or breast care nurse may talk to you about the stage ('anatomical stage') of your early breast cancer, metastatic breast cancer, DCIS or LCIS. This is a way of summarising how advanced the cancer is at the time of diagnosis.

Knowing the stage is important because it helps your treating team plan your treatments. 

The stage is described as stage 0, 1, 2, 3, 4 (or stage 0, I, II, III and IV). This number provides information about:

• the size of the cancer or tumour
• whether any lymph nodes are affected (have cancer in them)
• if the cancer has spread to other parts of the body.
• This anatomical stage is based on the TNM system (Tumour, Nodes, Metastasis), which your team may mention.

Doctors identify the stage from imaging reports and pathology reports. If there is anything you do not understand, talk to a member of your treating team.

The pathology report sometimes also shows a 'prognostic' stage, which looks at extra factors:

• tumour grade – how abnormal the cancer cells look under a microscope
• hormone receptor status – is the cancer positive for oestrogen (ER) or progesterone (PR) receptors
• HER2 status – are the cancer cells producing excess HER2 protein, which affects growth. 

This gives a more detailed prediction of how the cancer may respond to treatment, and the overall outcome.

Stage 0 breast cancer

Stage 0 is the earliest stage of breast cancer, when it is 'pre-invasive', such as DCIS and LCIS.

Pre-invasive means the cancer cells are contained in the milk ducts (for DCIS) or lobules (for LCIS). They have not spread to other tissue in the breast or other parts of the body.

Stage 1 breast cancer

Stage 1 refers to invasive breast cancers.

When breast cancers are stage 1:

• they are smaller than 2cm
• they have not spread outside the breast to the lymph nodes in the armpit (axilla) or any other part of the body.

Example: 
A stage 1 early breast cancer could be 15mm in size, with no sign it has spread to the lymph nodes.

Stage 2 breast cancer

Stage 2 breast cancer is divided into two groups: Stage 2A and Stage 2B.

Stage 2A breast cancers can mean any of the following:

• no cancer is seen in the breast, but cancer cells are found in 1 to 3 lymph nodes in the armpit (axilla)
• the cancer in the breast is less than 2cm and has spread to between 1 and 3 lymph nodes in the armpit
• the cancer in the breast is between 2cm and 5cm but has not spread to lymph nodes in the armpit.

Stage 2B breast cancers can mean:

• the cancer in the breast is between 2cm and 5cm and has spread to 1 to 3 lymph nodes in the armpit (axilla)
• the cancer in the breast is larger than 5cm and has not spread to lymph nodes in the armpit.

Example: stage 2 early breast cancer
A stage 2 early breast cancer could be:

• 2A - 15mm tumour with cancer cells found in 1 lymph node
• 2B - 25mm tumour with cancer cells in 1 lymph node

Stage 3 breast cancer

Stage 3 breast cancer is divided into 3 groups: stage 3A, stage 3B and stage 3C. Breast cancers that are stage 3 are also referred to as 'locally advanced breast cancer'.

Locally advanced breast cancer has not spread to other parts of the body, such as the bones or other organs.

Stage 3A can mean:

• no cancer is seen in the breast but cancer is found in 4 to 9 lymph nodes in the armpit or near the breastbone
• the cancer is larger than 5cm and is also found in 1 to 9 lymph nodes in the armpit or near the breastbone
• the cancer is smaller than 5cm and is also found in 4 to 9 lymph nodes in the armpit or near the breastbone.

Stage 3B can mean:

• the cancer in the breast can be of any size
• it has spread into the chest wall or the skin of the breast
• cancer is found in up to 9 lymph nodes under the armpit or near the breastbone.

Stage 3C can mean:

• the cancer in the breast can be of any size
• cancer is found in 10 or more lymph nodes under the armpit or near the breastbone, or nodes above or below the collarbone.

Sometimes cancers that are stage 2B can also be called 'locally advanced'.

Example: Locally advanced breast cancer
A stage 3 breast cancer could:

• be 6cm in size
• have spread to 5 lymph nodes in the armpit
• have spread to the skin of the breast.

Read about Locally advanced breast cancer.

Stage 4 breast cancer

Stage 4 refers to breast cancer that has spread to distant parts of the body, such as the bones, lungs, liver or brain.

The cancer in the breast can be any size and there may be no evidence in the lymph nodes in the armpit, or there may be many affected.

Stage 4 breast cancer is also called metastatic breast cancer, advanced breast cancer or secondary breast cancer.

Currently, metastatic breast cancer is a life-limiting illness that is not curable. With modern medicines, though, metastatic breast cancer is becoming very treatable, and people often live with it for years. Read about Metastatic breast cancer.

Questions to ask your treating team

• Ask your doctor or breast care nurse to write down and explain the stage of your breast cancer.
• Ask your doctor how the stage of the breast cancer will help to determine your treatment.