Stage 1 breast cancer

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.

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. There are different systems used in the UK to stage breast cancer. Stage 1 is part of the number staging system. Doctors may also use the TNM staging system.  

Staging for breast cancer is very complex. Many different factors are considered before doctors can confirm your final stage. Speak to your doctor or breast cancer nurse specialist if you have any questions about your staging.

Stage 1 can be divided into 1A and 1B. Below is a simplified description of stage 1A and 1B breast cancer. 

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 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
Diagram showing stage 1B breast cancer

TNM stages

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

  • T describes the size of the tumour (cancer)
  • 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 number staging helps your doctor decide which treatment you need. Treatment also depends on:

  • the type of cells the cancer started in
  • whether your cancer cells have receptors for particular cancer drugs
  • the grade of the cancer 
  • whether you have had the menopause Open a glossary item 
  • other health conditions you may have

Your doctor will take many different factors into account when deciding which treatment is best for you.

Surgery is the usual treatment for stage 1 breast cancer. There are different types of surgery you might have:

  • surgery to remove just the cancer a border of normal breast tissue around it. This is called breast conserving surgery or a wide local excision. 
  • surgery to remove the whole breast (mastectomy). You can then choose to have a new breast made (a breast reconstruction).

Treatments you might have after surgery

You may have other treatments after surgery. They include:

  • radiotherapy 
  • chemotherapy 
  • hormone therapy
  • targeted cancer drugs
  • drugs that strengthen the bones called bisphosphonates 

Checking the lymph nodes

Before your surgery, you have an ultrasound scan to check the lymph nodes in the armpit (axilla). 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 Open a glossary item biopsy during your breast cancer operation
  • surgery to remove the lymph nodes under your arm

Other stages of breast cancer

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

  • TNM Classification of Malignant Tumours (8th edition)
    Union for International Cancer Control
    J Brierley, M Gospodarowicz and C Wittekind   
    Wiley Blackwell 2017

  • Early and locally advanced breast cancer: diagnosis and management
    National Institute for Health and Care Excellence (NICE), 2018. Last updated April 2023

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

  • Cancer: Principles and Practice of Oncology (12th edition)
    VT DeVita, TS Lawrence, SA Rosenberg
    Wolters Kluwer, 2023

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
31 May 2023
Next review due: 
31 May 2026

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