What is mammography?

Mammography is basically an X-ray of the breast.


Mamma is Latin for breast and mammography is a type of breast X-ray that uses only a limited amount of radiation. It can identify breast cancer in its early stages.

What are the benefits of mammography?

Because mammography can identify breast cancer in its early stages, cancers detected in this way are smaller and therefore more likely to be non-invasive than cancers detected by women through self-examination. They are also less likely to have spread to the lymph glands under the arm than cancers that present with symptoms.

Who is given mammography?

Once a woman reaches the age of 50, she will be invited to take part in a breast screening programme. In the UK, this means having a mammogram every three years up to the age of 64.

The aim of screening by mammography is to pick up cancer while it is still small before it has a chance to spread.

If a woman wants to continue to be screened after the age of 64 she will need to make an appointment by phoning the breast screening unit or visiting the screening van when it is in her area.

There are various reasons why women are not normally screened below the age of 50:

breast cancer is less common in younger women.

mammography is less likely to detect breast cancer in young women because the breast tissue is denser, which can make breast cancer much more difficult to detect.

there is no evidence that breast screening below the age of 50 is cost effective.

However, young women who are at very high risk of developing breast cancer because of their family history or because they have had a biopsy that has shown a particular abnormality, are often offered screening at an earlier stage in their lives. This is usually by mammography and it is performed more regularly than in older women. There are studies currently being carried out into the effectiveness of other types of scans such as magnetic resonance imaging (MRI) in young high-risk women.

What do I need to know before the examination?

On the day of the examination patients should not use talcum powder or cream around the area of the breast or armpit.

What happens during the examination?

The patient will be asked to undress to the waist and stand in front of the X-ray machine. The radiographer will then position each breast in turn between two Perspex plates so that it is compressed and flattened. A brief pulse of X-ray is then used to take images of each breast. Normally two images per breast are taken on the first visit and one or two on every subsequent visit.

Some women find the experience uncomfortable and a few say it is painful but for the majority there is no more than minor discomfort. In any case, it is over very quickly.

What happens after the examination?

The X-ray film will be examined and the patient will be told the results by their screening centre in about 10 days. A minority of women will be asked to return for a second mammogram either because something has shown up that requires further investigation, or because there is a technical problem with the first X-ray. Bear in mind that being recalled does not mean the patient has breast cancer.

Of every 10,000 women who have a mammogram, 500 will be recalled for assessment, 80 will need to have an operation and 60 will have cancer. This means that just over 1in 10 of the women who are recalled after the first mammogram for further investigation have cancer.

How accurate is mammography?

Mammographic screening has a high sensitivity, and if a tumour is present in a woman over the age of 50, it is very uncommon for that tumour not to be detected by mammography.

Is mammography safe?

Modern screening equipment emits an extremely low dose of radiation and the chances that a mammogram will cause a cancer to develop is therefore extremely small. The benefits in terms of the number of cancers detected far outweigh the small risks of mammography. Although there is a lot of very negative publicity about screening, repeated studies have shown that the number of deaths from breast cancer in the age group 50 to 64 are reduced by 40 per cent in those who attend for breast screening.

Can mammography show whether a tumour is benign or malignant?

Mammograms are a good way of identifying abnormalities in the breast but they don't always show whether those abnormalities are benign (non-cancerous) or malignant (cancerous). Further tests are sometimes necessary.

What further investigation may be necessary?

If a patient is recalled, then as well as further mammograms she may require an ultrasound scan or a fine needle aspiration cytology (FNAC).

Ultrasound, which is familiar to many women because it is used to look at babies during pregnancy, can also be used in the breast to tell whether a lump is fluid or solid. If an abnormal shadow is seen on the mammogram, ultrasound is an accurate way of judging whether any abnormality is benign and straight forward or whether it is more likely to be serious.

Inserting a needle into the lump will show whether it is full of fluid (a cyst) or solid. The needle can allow a sample of cells to be removed for examination under the microscope and this is a very accurate method of finding out whether the lump is benign or malignant.

Because any abnormality in the breast may be so small that it is impalpable, meaning that the doctor cannot feel it (impalpable), there are techniques for allowing samples of such lesions to be removed either using the mammogram machine or the ultrasound to guide a needle into the area of abnormality. If there is an abnormality on the mammogram but no lump to feel, then by using either the X-ray machine or the ultrasound machine it is possible to guide the needle into the area of abnormality and to obtain enough cells or tissue to obtain a definite diagnosis.

Sometimes these impalpable lesions need to be removed. This is achieved by placing a hooked wire using the X-rays or ultrasound to guide the wire into the tissue. The surgeon then follows the wire to the end and removes the abnormal area.