Stage 1

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.

Staging for breast cancer is very complex. Below is a simplified description. Many different factors are considered before doctors can plan your treatment. 
For example, they also use a sample of your cancer to test for:

  • receptors for the female hormones (oestrogen and pogesterone)
  • HER2 status (human epidermal growth factor receptor 2)
  • the grade of your cancer

Do speak to your breast doctor or nurse if you have any questions about your staging.

Stage 1 breast cancer has 2 groups.

Stage 1A

Stage 1A means that the cancer 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 breast conserving surgery or a wide local excision. After this you usually have 3 weeks of radiotherapy to the rest of the breast. In some hospitals, you may have this over a shorter time. 

Or you might have the whole breast removed (mastectomy). You can choose to have a new breast made (a breast reconstruction).

Checking the lymph nodes

The usual treatment is surgery to remove the cancer. Before your surgery you have an ultrasound scan to check the lymph nodes in the armpit (axilla) close to the breast. This is to see if they contain cancer cells. If breast cancer spreads, it usually first spreads to the lymph nodes close to the breast.

Depending on the results of your scan you might have:

  • a sentinel lymph node biopsy during your breast cancer operation
  • surgery to remove your lymph nodes

You may have other treatments after surgery.

Hormone therapy

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 there are features of the cancer that show you may benefit from having it. This can include cancers that are larger than 1cm, or if the cells look very abnormal (a high grade tumour).

Your doctor will discuss this with you and explain both the risks and benefits.

Targeted cancer therapy

Your cancer cells are tested to see if they have receptors for a protein called HER2 (known as HER2 positive cancer). You have a targeted cancer drug called trastuzumab (Herceptin) as well as chemotherapy if you have HER2 positive cancer. You usually have this treatment for a year.

Bone strengthening treatment 

You may also have treatment with a group of drugs that strengthen the bones. These are called bisphosphonates. For some people, this treatment can help reduce the risk of their breast cancer spreading to the bones. You may have this if you have early stage breast cancer and no longer have periods (post menopausal).

Other stages

Last reviewed: 
10 Jul 2020
Next review due: 
10 Jul 2023
  • TNM Classification of Malignant Tumours (8th edition)
    Union for International Cancer Control
    J Brierley, M Gospodarowicz and C Wittekind   
    Wiley Blackwell 2017

  • AJCC Cancer Staging Manual (8th edition)
    American Joint Committee on Cancer
    Springer, 2017

  • Early and locally advanced breast cancer: diagnosis and treatment
    National Institute for Health and Care Excellence (NICE) June 2018

  • Early Breast Cancer: ESMO Clinical Practice Guidelines 2019
    F Cardoso and others
    Annals of Oncology, 2019. Volume 30, Issue 8, Pages 1194–1220