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Stage 1

Find out about stage 1 breast cancer and the treatments used.

Stage 1 breast cancer means that the cancer is small and only in the breast tissue or it might be found in lymph nodes close to the breast.

It is an early stage breast cancer. 

Stage 1 breast cancer has 2 groups.

Stage 1A

Stage 1A means that the tumour is 2 centimetres (cm) or smaller and has not spread outside the breast

Diagram showing stage 1A breast cancer

Stage 1B

Stage 1B means that small areas of breast cancer cells are found in the lymph nodes close to the breast and that:

  • no tumour is found in the breast or
  • the breast tumour is 2cm or smaller
Diagram showing stage 1B breast cancer

TNM stages

The TNM staging system stands for Tumour, Node, Metastasis.

  • T describes the size of the tumour
  • N describes whether there are any cancer cells in the lymph nodes
  • M describes whether the cancer has spread to a different part of the body

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


The usual treatment is surgery to remove the cancer. There are different types of surgery.

You might have just the cancerous area removed with a border of normal breast tissue. This is called a wide local excision or lumpectomy. After this you usually have several weeks of radiotherapy to the rest of the breast.

Or you might have the whole breast removed (mastectomy). You can choose to have a new breast made (a breast reconstruction). You don't usually need radiotherapy after this kind of surgery but some women do need it.

Your doctor will also check the lymph nodes close to the breast to see if they contain cancer cells. You either have a test called a sentinel lymph node biopsy (SLNB) or surgery to remove some of the lymph nodes under the arm.

You usually have other treatments after surgery.

Some cancer cells have hormone receptors for the female hormones oestrogen or progesterone. You usually have hormone therapy for at least 5 years if your cancer cells have hormone receptors.

You might have chemotherapy if your cancer is larger than 1cm, or the cells look very abnormal (a high grade tumour). 

You might have a targeted cancer drug called trastuzumab (Herceptin) as well as chemotherapy if your cancer cells have receptors for a protein called Her2 (known as Her2 positive cancer). You usually have this for a year. 

Other stages

Last reviewed: 
03 Oct 2017
  • TNM Classification of Malignant Tumours (7th edition)
    International Union Against Cancer   
    LH Sobin, MK Gospodarowicz, CH Wittekind
    John Wiley and Sons, 2009

  • AJCC Cancer Staging Manual (7th edition)
    American Joint Committee on Cancer
    Springer, 2010

  • Early and locally advanced breast cancer: diagnosis and treatment
    National Institute for Health and Care Excellence, 2009 (updated March 2017)

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