Stages and grading

When breast cancer is diagnosed, it is important to know the stage and grade of the cancer. This helps your doctors decide on the best treatment for you. The stage of a cancer describes its size and whether it has spread from where it started. The grade of a cancer describes how the cancer cells look compared to normal cells and how quickly they grow.

The most common systems to describe the stage of a cancer are number staging and TNM staging:

  • Number staging describes breast cancer in stages. These go from stage 0 (the cancer cells are in the ducts of the breast) through to stage 4 (the cancer has spread to other parts of the body).
  • TNM staging looks at the size of the cancer, whether it has spread to the lymph nodes or to other parts of the body.

To grade a breast cancer, a doctor examines a sample of the cancer cells under a microscope. They grade the cells from grades 1–3, or from low-grade to high-grade.

Staging and grading for breast cancer

Your breast specialist needs certain information about the cancer to help plan the best treatment for you. This includes the stage of the cancer, its grade and whether it has receptors for hormones, proteins or both. Your specialist doctor and nurse will talk this over with you.


Staging

The stage of a cancer describes its size and if it has spread from where it started. This information affects the decisions you and your doctor make about your treatment. They won’t know the exact stage of the cancer until after your operation.


TNM staging

In the TNM staging system, TNM stands for Tumour, Nodes and Metastases:

T describes the size of the tumour.

N describes whether the cancer has spread to the lymph nodes and which nodes are involved. For example, N0 means no lymph nodes are affected, while N1 means there are cancer cells in 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.


The number stage

Breast cancer can also be divided into four number stages:

Stage 0

This describes non-invasive breast cancers. Ductal carcinoma in situ (DCIS) is sometimes described as stage 0.

The following four stages are known as invasive breast cancer:

Stage 1

Stage 1 is divided into two stages:

  • Stage 1A – The cancer (lump) is 2cm or smaller and has not spread outside the breast tissue.
  • Stage 1B – The cancer is not found in the breast tissue (or is less than 2cm) and there are a few cancer cells in the lymph nodes under the arm. 

Stage 2

Stage 2 is divided into two stages:

  • Stage 2A – The cancer is not found in the breast tissue or is smaller than 2cm and has spread to lymph nodes. Or the cancer is bigger than 2cm (but under 5cm) and hasn’t spread to the lymph nodes.
  • Stage 2B – The cancer is bigger than 2cm but not bigger than 5cm and has spread to the lymph nodes in the armpit. Or the cancer is bigger than 5cm but has not spread to the lymph nodes.

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

Stage 3

Stage 3 is divided into three stages:

  • Stage 3A – The cancer is not found in the breast or is any size and has spread to four to nine lymph nodes in the armpit. Or the cancer is bigger than 5cm and has spread to a few lymph nodes.
  • Stage 3B – The cancer has spread to tissue near the breast and may be attached to skin or muscle (causing ulcers). There are usually cancer cells in the lymph nodes.
  • Stage 3C – The cancer has spread to 10 or more lymph nodes in the armpit, below the breastbone, near the neck or under the collarbone.

Sometimes stage 3 breast cancer is called locally advanced breast cancer. Cancer that has spread to the skin may be inflammatory breast cancer.

Stage 4

This is when the cancer has spread to other parts of the body such as the bones, liver or lungs. This is called secondary or metastatic breast cancer.


Grading

Grading is about how the cancer cells look under the microscope compared with normal cells. The grade helps your doctor to decide if you need further treatment after surgery.

  • Grade 1 or low-grade or well differentiated - the cancer cells look similar to normal cells and usually grow slowly and are less likely to spread.
  • Grade 2 or moderate-or intermediate-grade - the cancer cells look more abnormal and are slightly faster growing.
  • Grade 3 or high-grade or poorly differentiated - the cancer cells look very different from normal cells and may grow more quickly.

Back to Understanding your diagnosis

Treatment overview

The treatment you have will depend on the stage of the cancer. Surgery is usually the main treatment for early breast cancer in men.