The TNM staging system

The TNM staging system

The TNM system considers the tumour (T), the lymph nodes (N) and the presence of any distant spread (or metastases, M).

See also the Cancer Research UK Staging System

Tumour (T)

• T1 - The tumour is no more than 2 cm across T1 is further divided into 3 groups
  • 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 is fixed to the chest wall
  • T4b - The tumour is fixed to the skin
  • T4c - The tumour is fixed 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

Nodes (N)

• N0 - No cancer cells found in any nodes
• N1 cancer in nodes in the armpit but nodes not stuck to other structures

• 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 under the breast bone (the internal mammary nodes). These 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 is cancer in lymph nodes below the collarbone
  • N3b - There is cancer in lymph nodes in the armpit and under the breast bone
  • N3c - There is cancer in lymph nodes above the collarbone

Metastases (M)

• M0 - No sign of cancer spread
• M1 - Cancer has spread to another part of the body, apart from the breast and lymph nodes under the arm

Although summarising the information about a cancer as a stage can sometimes be useful, we will always give you more detailed information about your cancer.

This will include the size, the type, the grade (an indication of how quickly it has grown), the presence of any involved lymph glands, as well as other factors such as the hormone receptor status and the sensitivity to other drugs, such as Herceptin.

All of this information allows a detailed assessment of what extra treatment may be required.