A mammogram is a low-dose X-ray of the breast that can be performed to help with the detection and diagnosis of breast cancer.

Screening mammograms

Screening mammograms are performed on women without any symptoms of breast cancer as a way of detecting breast cancer in its early stages, when treatment is most likely to be successful. Screening mammograms can detect breast cancers that are too small to be felt as lumps in the breast.

Recommendations for screening mammography

The national breast cancer screening program, BreastScreen Australia, offers free mammograms to women throughout Australia. BreastScreen Australia is targeted specifically at women without symptoms aged 50 to 74 years.

Women aged between 50 and 74 years are encouraged to have 2-yearly screening mammograms. This is because increasing age is the biggest risk factor for breast cancer, and 75 per cent of all breast cancers affect women aged over 50 years.

Women aged 40 to 49 years and women older than 75 years are also eligible to have free screening mammograms if they choose to, but should discuss it with their GP first.

Regular screening mammograms are not recommended for women younger than 40. Screening mammograms are less reliable in women who are younger than 40 years because the density of their breast tissue makes it difficult to be able to detect breast cancers. Also, there is a lower risk of breast cancer in women this age compared with older women.

Other screening tests

Breast Magnetic Resonance Imaging (MRI) is also used to screen some women, particularly those aged less than 50 years who have a high genetic risk of breast cancer.

Changes in your breasts
Of course, women of any age who notice changes in their breasts should see their doctor. Changes include:

  • change in breast size;
  • change in breast shape or appearance;
  • skin changes on the breast;
  • change in the appearance of the nipple;
  • nipple discharge;
  • a breast lump; and
  • pain in the breast.

Also see your doctor if you are concerned about your individual risk of breast cancer.

Diagnostic mammograms

Diagnostic mammograms are a more complex X-ray of the breast, performed as part of the investigation of a breast problem, such as a breast lump, pain, skin change or nipple discharge.

Diagnostic mammograms are also performed to further evaluate any abnormalities that may have been detected during a screening mammogram.


The risks associated with having a mammogram include:

  • exposure to low-level radiation; and
  • getting a false-positive result (when the mammogram result indicates possible breast cancer, but further investigation reveals no cancer).

However, for most women, the benefits of regular mammograms outweigh the risks.

Modern mammography machines use the smallest amount of radiation possible, meaning there is minimal exposure to radiation.

While false-positive results are associated with stress and anxiety and the need for further testing, it’s important to remember that most abnormal findings seen on mammograms are not cancer.

Abnormal mammogram results

Having an abnormal mammogram is understandably a worrying experience. But it is important to remember that most abnormal mammograms do not mean breast cancer.

A number of things other than cancer can produce an abnormality on your mammogram.

  • Shadows — these can due to increased density of breast tissue or harmless (benign) cysts.
  • Calcium deposits (calcification) — although large numbers of tiny calcium deposits may be associated with cancer, calcification can also be caused by ageing, injury or a benign lump such as a fibroadenoma.
  • Scarring — this might be due to a previous breast surgery or biopsy.

Tests after an abnormal mammogram

If your mammogram is abnormal, further tests will be necessary to determine the exact cause of the abnormality.

You may need to have further mammograms, looking more closely at the site of the abnormality. Sometimes an ultrasound of the breast is needed. This painless test can help tell if cysts are present.

Samples of breast tissue may be needed for examination under the microscope. These samples are obtained in a variety of ways.

  • Fine needle aspiration — cells are obtained through a narrow needle attached to a syringe.
  • Core biopsy — a small sample of tissue is removed with a needle, usually under local anaesthetic. The biopsy may be guided by an X-ray or ultrasound.
  • Surgical biopsy — the suspicious area is sampled or removed in an operation. This is usually under general anaesthetic. A thin wire may be inserted under X-ray control immediately before the biopsy to indicate the abnormal area. The surgeon will then be able to locate the wire and be sure of sampling the correct area.

All these procedures are relatively painless and are aimed at eliminating the possibility of breast cancer. If you are found to have breast cancer, early detection and removal greatly increase your chance of a complete recovery.