Staging and grading of breast cancer

The stage of a cancer describes its size and whether it has spread from where it started. There are different ways to describe the stage of a cancer. The most commonly used ones are the TNM staging system and the number staging system.

The TNM staging system gives the complete stage of the cancer:

• T describes the size of the tumour.
• N describes whether the cancer has spread to the lymph nodes and which nodes are affected. For example, N0 means no lymph nodes are affected. N1 means there are cancer cells in 1 to 3 of the lymph nodes.
• M describes whether the cancer has spread to another part of the body (metastasised). For example, M0 means the cancer has not spread to other parts of the body.

Sometimes the final TNM staging may not be certain until after surgery to remove the cancer.

Breast cancer can also be divided into 4 number stages under the TNM system. 

This information is about stage 1 to 3 breast cancer.

Stage 1 or 2 breast cancer is usually called early breast cancer.

Stage 1

Stage 1 is divided into 2 stages:

• Stage 1A
  The cancer is 2cm or smaller. It has not spread outside the breast.
• Stage 1B
  The cancer is not found in the breast tissue or is 2cm or smaller. Tiny numbers of cancer cells have spread to lymph nodes in the armpit. These cells are called micrometastases.

Stage 2

Stage 2 is divided into 2 stages:

• Stage 2A
  The cancer cannot be found in the breast tissue. Or it is 2cm or smaller. It has also spread to 1 to 3 lymph nodes in the armpit or near the breastbone.
  Or
  The cancer is between 2 and 5cm. And it has not spread to the lymph nodes in the armpit or near the breastbone.
• Stage 2B
  The cancer is between 2 and 5cm. It has spread to 1 to 3 lymph nodes in the armpit.
  Or
  The cancer is bigger than 5cm but has not spread to the lymph nodes.

Stage 3

Stage 3 breast cancer is sometimes called locally advanced breast cancer. The cancer has spread to the lymph nodes, the skin of the breast or the chest muscle. The skin may be red, swollen or have broken down, causing an ulcer. Some breast cancers that have spread to the skin may be inflammatory breast cancer.

Stage 3 is divided into 3 stages:

• Stage 3A
  The cancer cannot be found in the breast. Or it is 5cm or smaller. It has spread to 4 to 9 lymph nodes in the armpit.
  Or
  The cancer is bigger than 5cm. It has spread to up to 3 lymph nodes in the armpit or near the breastbone.
• Stage 3B
  The cancer has spread into tissue nearby, such as the skin of the breast and the chest muscle underneath. It may have spread to 1 to 9 lymph nodes in the armpit.
• Stage 3C
• The cancer may be any size. Or it cannot be found in the breast. It has spread into tissue nearby, such as the skin of the breast and the chest muscle underneath. It has spread to 10 or more lymph nodes in the armpit.The cancer has spread to lymph nodes below the breastbone and above or below the collarbone. It has spread to 4 or more lymph nodes in the armpit.

Stage 4

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

• Stage 4
  The cancer has spread to other parts of the body, such as the bones, liver or lungs.

This information is about stage 1 to 3 breast cancer. If you have stage 4 breast cancer, you may find our information about secondary breast cancer helpful.

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

• use plain English
• explain medical words
• use short sentences
• use illustrations to explain text
• structure the information clearly
• make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.