Stages and grades of breast cancer
The stage of a cancer tells you how big it is and how far it has spread. It helps your doctor decide the best treatment for you. Doctors use different systems to stage breast cancer in the UK.
This page is about the number staging system. The number staging system divides breast cancer into 4 stages. These are numbered from 1 to 4.
Doctors may also use the TNM staging system. The TNM system is the most common way to stage breast cancer in the UK.
On this page we describe each number stage. And we explain what each number stage means using the TNM system.
TNM stands for Tumour (T), Node (N) and Metastasis (M).
T describes the size of the tumour (cancer)
N describes whether there are any cancer cells in the nearby lymph nodes
M describes whether the cancer has spread to parts of the body further away from where the cancer started
The doctor gives each factor (T, N and M) a number depending on how far the cancer has grown or spread.
For example, a very small cancer which hasn't spread to the lymph nodes or elsewhere in the body may be T1 N0 M0.
A larger cancer that has spread into the nearby lymph nodes and to another part of the body may be T3 N1 M1.
Read about the TNM staging system for breast cancer
You may hear about stage 0 breast cancer. Stage 0 is used to describe ductal carcinoma in situ (DCIS). This means that the cancer cells are in the breast ducts and have not spread into the surrounding breast tissue. It is different to invasive breast cancer.
In the TNM staging system, DCIS is the same as Tis N0 M0.
Read about ductal carcinoma in situ
Stage 1A means that the cancer is 2 centimetres (cm) or smaller and has not spread outside the breast.
Stage 1B means that a few breast cancer cells are found in the lymph nodes close to the breast and that:
no cancer is found in the breast or
the breast cancer is 2 cm or smaller
In the TNM staging system, stage 1A breast cancer is the same as T1 N0 M0.
Stage 1B is the same as:
T0 N1mi M0
T1 N1mi M0
Stage 2A means one of the following:
no cancer is found in the breast or the breast cancer is 2 centimetres (cm) or less, and cancer cells are found in 1 to 3 in the armpit or in the lymph nodes near the breastbone
the cancer is larger than 2 cm but not larger than 5 cm and there is no cancer in the lymph nodes
Stage 2B means one of the following:
the cancer is larger than 2 cm but not larger than 5 cm and there are small areas of cancer cells in the lymph nodes
the cancer is larger than 2 cm but not larger than 5 cm and the cancer has spread to 1 to 3 lymph nodes in the armpit or to the lymph nodes near the breastbone
the cancer is larger than 5cm and hasn't spread to the lymph nodes
In the TNM staging system, stage 2A breast cancer is the same as:
T0 N1 M0
T1 N1 M0
T2 N0 M0
Stage 2B is the same as:
T2 N1 M0
T3 N0 M0
Stage 3A means one of the following:
no cancer is seen in the breast or the cancer is of any size within the breast. And there is cancer in 4 to 9 lymph nodes under the arm or in lymph nodes near the breastbone
the cancer is larger than 5 cm and has spread to 1 to 3 lymph nodes under the arm or to the lymph nodes near the breastbone
Stage 3B means the cancer has spread to the skin of the breast or the chest wall. The chest wall means the structures surrounding and protecting the lungs, such as the ribs, muscles, skin or connective tissues.
The cancer may have 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 nodes near the breastbone.
Cancer that has spread to the skin of the breast might be an inflammatory breast cancer.
Find out about inflammatory breast cancer
Stage 3C means the cancer can be any size, or there may be no cancer seen in the breast. The cancer may have grown into the chest wall or skin of the breast. The cancer has spread to one of the following:
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
In the TNM staging system, stage 3A breast cancer is the same as:
T0 N2 M0
T1 N2 M0
T2 N2 M0
T3 N1 M0
T3 N2 M0
Stage 3B is the same as:
T4 N0 M0
T4 N1 M0
T4 N2 M0
Stage 3C is the same as:
Any T N3 M0
In stage 4 breast cancer:
the cancer 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 or brain
In the TNM staging system, stage 4 breast cancer is the same as:
Any T Any N M1
Your cancer stage helps your doctor decide which treatment you need. Your doctor will take many other factors into account when deciding which treatment is best for you. These include:
the type of cells the cancer started in
whether your cancer cells have for particular cancer drugs
the of the cancer
whether you have had the
other health conditions you have
Last reviewed: 05 Jun 2026
Next review due: 05 Jun 2029
The TNM system is a way of staging breast cancer. TNM stands for Tumour, Node, Metastasis. It is the most common way to stage breast cancer in the UK.
The stage tells you how big your cancer is and whether it has spread. The grade means how abnormal the cells look under a microscope.
You have a number of tests to check for breast cancer. This includes a breast examination, a mammogram, a biopsy and scans.
Treatment for breast cancer depends on a number of factors. The main treatments are surgery, chemotherapy, radiotherapy, hormone therapy, and targeted and immunotherapy drugs.
Breast cancer is cancer that starts in the breast tissue. It’s the most common cancer in the UK. It mainly affects women, but men can get it too.
Find out about breast cancer, including symptoms, diagnosis, treatment, survival, and how to cope with the effects on your life and relationships.
