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Diagnosis - Breast cancer in women

You may be diagnosed with breast cancer after breast screening, or after a visit to your GP with symptoms.

A specialist can diagnose breast cancer using tests such as:

  • a mammogram (x-ray of your breast)
  • biopsy (when a sample of tissue cells are tested for cancer)

Contact your GP if you have symptoms

Urgent advice: Contact your GP as soon as possible if:

you notice any symptoms of breast cancer such as:

  • an unusual lump in your breast
  • any change in the appearance, feel or shape of your breasts

Symptoms of breast cancer in women

Your GP will examine you. If you need tests, they'll refer you to a specialist breast cancer clinic.

Tests for breast cancer

Tests for breast cancer are usually done in:

  • a specialist breast cancer clinic after a referral from your GP
  • a BreastCheck assessment clinic after breast screening

Mammogram and breast ultrasound

If you have symptoms and have been referred to a specialist breast clinic by your GP, you'll probably have a mammogram if you are over age 35.

A mammogram is an x-ray of the breast. It is used to find breast cancer when it's too small to see or feel.

You may also need an ultrasound scan.

Ultrasound uses high-frequency sound waves to produce an image of the inside of your breasts. It shows lumps or abnormalities. It may be used to find out if a lump in your breast is solid or contains liquid.

If your cancer was detected through the BreastCheck screening programme, you may need another mammogram or ultrasound scan.

Mammograms and dense breast tissue

Younger women usually have denser breasts. This is why you might not have a mammogram if you are under age 35.

Your breasts are made up of thousands of tiny glands (lobules) that produce milk. This glandular tissue (non-fatty tissue) contains a higher concentration of breast cells than other breast tissue (fatty tissue), making it denser.

Dense breast tissue (non-fatty tissue) looks solid and white on a mammogram. You cannot see through it. This makes the mammogram more difficult to read.

It means lumps or areas of abnormal tissue are harder to spot. This is why mammograms may be less effective for women with dense breasts.

As you get older, the amount of glandular tissue in your breasts decreases and is replaced by fat. This means your breasts become less dense.

Dense breasts and cancer risk


A biopsy is where a sample of tissue cells is taken from your breast and tested to see if it's cancerous.

You may also need a scan and a biopsy on lymph nodes in your armpit (axilla) to see if these are also affected.

Biopsies can be taken in different ways. The type you have will depend on your mammogram or ultrasound results.

You have a local anaesthetic for the biopsy. You will be awake but you will not feel anything.

Needle biopsy

A needle biopsy is the most common type of biopsy.

A sample of tissue is taken from a lump in your breast using a large needle.

You may have a local anaesthetic, which means you'll be awake during the procedure, but your breast will be numb.

Your doctor may suggest that you have a guided needle biopsy to get a more precise and reliable diagnosis.

This is when they are guided by one of these:

  • ultrasound
  • x-ray
  • MRI

Fine needle aspiration

Needle aspiration may be used to test a sample of your breast cells for cancer or drain a small fluid-filled lump (benign cyst).

Your doctor will use a small needle to take a sample of cells, without removing any tissue.

Further tests for breast cancer

If a diagnosis of breast cancer is confirmed, sometimes more tests will be needed to determine the stage and grade of the cancer and treatment.

Tests to find out the stage

You may have more tests to determine the stage of the cancer and check if the cancer has spread. Your doctor will discuss with you if these are needed.

The tests may include:

  • CT scan
  • chest x-ray
  • ultrasound scan of your abdomen (tummy)
  • bone scan

You may need an MRI scan of your breast. This can be used to may be needed to clarify the results and the extent of the cancer in your breast.

Stage and grade of breast cancer

When your breast cancer is diagnosed, the doctors will give it a stage.

The stage describes:

  • the size of the cancer
  • how far it has spread

This helps them decide what treatment to use.

Stage of breast cancer

Stage 0 is sometimes called ductal carcinoma in situ (DCIS). The tumour is 'in situ' and it is pre-invasive.

Other stages of breast cancer describe invasive breast cancer:

Stage 1

The tumour measures less than 2cm and the lymph nodes in the armpit are not affected. There are no signs that the cancer has spread elsewhere in the body.

Stage 2

The tumour measures 2cm to 5cm. The lymph nodes in the armpit may be affected. There are no signs that the cancer has spread elsewhere in the body.

Stage 3

The tumour measures 2cm to 5cm and may be attached to skin, chest wall or surrounding tissue in your breast. The lymph nodes in the armpit are affected, there are no signs that the cancer has spread elsewhere in the body.

Stage 4

The tumour is of any size and the cancer has spread to other parts of the body (metastasis).

TNM staging system

The TNM staging system may also be used to describe breast cancer, as it can provide accurate information about the diagnosis:

  • T - the size of the tumour
  • N - if the cancer has spread to the lymph nodes
  • M - if the cancer has spread to other parts of the body

Grades of breast cancer

The grade describes the appearance of the cancer cells.

  • low grade (G1) - the cells, although abnormal, appear to be growing slowly
  • medium grade (G2) - the cells look more abnormal than low-grade cells
  • high grade (G3) - the cells look even more abnormal and are more likely to grow quickly

Content supplied by the NHS and adapted for Ireland by the HSE

Page last reviewed: 11 October 2023
Next review due: 11 October 2026

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.