TNM breast cancer staging
This page tells you about the staging of breast cancer, including TNM staging. You can find information about
What staging is
Staging describes the size of the cancer and whether it has spread to lymph nodes or other parts of the body. Finding the stage is important because it helps your breast cancer specialist to decide on the best treatment for you.
The staging system normally used in breast cancer is called TNM, which stands for tumour, node, and metastasis. TNM staging takes into account the size of the tumour, whether the cancer has spread to nearby lymph nodes, and whether it has spread to other parts of the body (metastasis).
The TNM stages of breast cancer
The T stages are numbered 1 to 4 and describe the size of the tumour. The N stages are numbered 0 to 3. They describe which lymph nodes contain cancer cells, if any.
There are 3 M stages – M0 means no sign of cancer spread, cMo(i+) means that cancer cells are present in blood, bone marrow, or far away lymph nodes but there is no sign on physical examination, scans or X-rays, and M1 means that the cancer has spread to another part of the body.
How TNM fits together
Your doctor will put these 3 TNM results together to give you your overall stage. So, for example, you might see a tumour described as T2 N0 M0. This would be a single tumour 2 to 5 cm across, with no evidence of spread to any lymph nodes and no evidence of spread outside the breast.
Staging and treatment
Doctors sometimes put staging information into a formula called the Nottingham Prognostic Indicator (NPI), or computer programmes such as Adjuvant! Online, to give some idea of how well treatment may work for an individual person with cancer.
You can view and print the quick guides for all the pages in the Treating breast cancer section.
Early breast cancer means the cancer has not spread beyond the breast or the lymph nodes in the armpit on the same side of the body. So, the cancer has not spread to any other part of the body.
Local recurrence means cancer that has come back in the area of the breast after treatment.
Locally advanced breast cancer means the cancer has not spread to another part of the body but may be
- Bigger than 5 cm across
- Growing into the skin or muscle of the chest
- Present in the lymph nodes in the armpit, and these lymph nodes are either stuck to each other, or to other structures
Secondary breast cancer is also called metastatic breast cancer or stage 4 breast cancer. It means that the cancer has spread to other parts of the body, such as the liver or bones.
The stage of a cancer looks at how big the cancer is and whether it has spread. 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. Specialists usually make decisions about treatment for breast cancer according to the TNM stage and the grade of the cancer.
TMN staging takes into account the size of the tumour (T), whether the cancer has spread to the lymph glands (lymph nodes) (N), and whether the tumour has spread anywhere else in the body (M – for metastases).
Doctors also sometimes use the number system of staging.
Below is a slightly simplified description of the TNM staging system for breast cancer.
TX means that the tumour size cannot be assessed
Tis means DCIS
T1 – The tumour is 2 centimetres (cm) across or less
T1 is further divided into 4 groups
- T1mi – the tumour is 0.1cm across or less
- T1a – the tumour is more than 0.1 cm but not more than 0.5 cm
- T1b – the tumour is more than 0.5 cm but not more than 1 cm
- T1c – the tumour is more than 1 cm but not more than 2 cm
T2 – The tumour is more than 2 centimetres, but no more than 5 centimetres across
T3 – The tumour is bigger than 5 centimetres across
T4 is divided into 4 groups
- T4a – The tumour has spread into the chest wall
- T4b – The tumour has spread into the skin and the breast may be swollen
- T4c – The tumour has spread to both the skin and the chest wall
- T4d – Inflammatory carcinoma – this is a cancer in which the overlying skin is red, swollen and painful to the touch
NX means that the lymph nodes cannot be assessed (for example, if they were previously removed)
N0 – No cancer cells found in any nearby nodes
Isolated tumour cells (ITCs) are small clusters of cancer cells less than 0.2 mm across, or a single tumour cell, or a cluster of fewer than 200 cells in one area of a lymph node. Lymph nodes containing only isolated tumour cells are not counted as positive lymph nodes
N1 – Cancer cells are in the upper levels of lymph nodes in the armpit but the nodes are not stuck to surrounding tissues
pN1mi – One or more lymph nodes contain areas of cancer cells called micrometastases that are larger than 0.2mm or contain more than 200 cancer cells but are less than 2mm
N2 is divided into 2 groups
- N2a – there are cancer cells in the lymph nodes in the armpit, which are stuck to each other and to other structures
- N2b – there are cancer cells in the lymph nodes behind the breast bone (the internal mammary nodes), which have either been seen on a scan or felt by the doctor. There is no evidence of cancer in lymph nodes in the armpit
N3 is divided into 3 groups
- N3a – there are cancer cells in lymph nodes below the collarbone
- N3b – there are cancer cells in lymph nodes in the armpit and behind the breast bone
- N3c – there are cancer cells in lymph nodes above the collarbone
M0 means that there is no sign of cancer spread
cMo(i+) means there is no sign of the cancer on physical examination, scans or X-rays but cancer cells are present in blood, bone marrow, or lymph nodes far away from the breast cancer – the cells are found by laboratory tests
M1 – means the cancer has spread to another part of the body
Your doctor puts the TNM results together to give you your overall stage. This is usually what the doctor writes on your test forms. So, for example, you might see a tumour described as T2 N0 M0. This would be
- A single tumour 2.1 to 5 cm across
- No evidence of spread to any lymph nodes
- No evidence of spread outside the breast
Putting the staging information into a formula called the Nottingham Prognostic Indicator (NPI) can give some idea of how well treatment may work for an individual person with breast cancer. The NPI can also give some idea of how long a 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.
If you would like more information about anything to do with breast cancer stages, you can contact the Cancer Research UK information nurses. They will be happy to help. You can find detailed information about the number system of breast cancer staging in this section. And there is more about staging cancers generally in our cancers in general section.
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