How DCIS is diagnosed
You'll usually be diagnosed with DCIS after having a mammogram (breast x-ray) as part of the NHS Breast Screening Programme.
Mammograms can detect changes in the breast tissue before they develop into a lump large enough to be felt. DCIS usually shows up as an area of tiny specks of calcium that collect in the milk ducts, known as micro-calcifications.
Not all micro-calcifications are due to cancer, so if any are found, you’ll have further tests to check them.
Occasionally, women go to their GP with breast symptoms and are diagnosed after being referred to a breast clinic for tests. A mammogram is normally one of the first tests used to check the breasts.
NHS breast screening programme
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The NHS breast screening programmes aim to find breast cancer very early so women have the best chance of the cancer being cured. In the UK, women aged 50–70 are invited to attend breast screening every three years as part of the NHS Breast Screening Programme. In England, the age range is gradually being extended to include women aged 47–73. At the moment Scotland, Wales and Northern Ireland continue to screen women aged 50–70.
When you go for breast screening, you have a mammogram taken of each breast.
Mammogram (breast x-ray)
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A mammogram is a low-dose x-ray of the breast. You’ll need to take off your top and bra for the mammogram. A radiographer will position you so that your breast is against the x-ray machine and is gently but firmly compressed with a flat, clear, plastic plate. Two mammograms are taken of each breast from different angles.
The breast tissue needs to be squashed to keep the breast still and to get a clear picture. Most women find this uncomfortable, and for some women it’s painful for a short time.
In younger women, the breast tissue is more dense (has less fat), which makes it difficult to detect any changes on the mammogram. For this reason, mammograms are usually only used for women over the age of 35-40. If screening is recommended for a younger woman, another method may be used, such as a digital mammogram that uses computer imaging rather than x-rays.
Breast calcifications are small areas where calcium has built up in the breast. They can’t be felt and can only be detected on a mammogram. Calcifications are very common, and in most cases are harmless. There are two types: micro-calcifications and macro-calcifications.
Micro-calcifications show up as fine white specks on a mammogram. They’re common as women get older and aren’t usually due to cancer. But in a small number of cases, a group of micro calcifications seen in one area (a cluster) may be a sign of DCIS or early breast cancer.
Macro-calcifications are seen as larger white dots or dashes on a mammogram. They’re a natural result of breast ageing and are common in women over 50. Macro-calcifications are harmless and don’t need any treatment or monitoring.
If you have any calcifications, a radiologist will look at the size, shape and pattern of them. If micro-calcifications are found, you’ll usually have a magnified mammogram to examine the area of calcification more closely.
We have more detailed information on breast calcifications that you might find helpful.
If the doctor thinks your mammograms show possible signs of DCIS, you’ll have further tests to find out more.