Potential Limitations of Mammograms

View facts and figures about breast screening, including information on overdiagnosis and breast density, from BreastScreen NSW.

What Do I Need to Be Aware Of?

Woman Reading Breast Screen NSW Booklet

In order to make an informed decision about breast screening, it’s handy to have an accurate understanding of its possible limitations, in addition to the benefits.

To assist you, we’ve outlined some of the concerns you may have heard about screening mammograms, along with more information to help you better understand these aspects.

You should also read about the benefits of breast screening here

Addressing Your Concerns About Breast Screening


What you may have heard: "Screening mammograms aren't always accurate"

The explanation: Screening mammograms are the most effective method of detecting breast cancer early. However, they aren’t 100% accurate; in a small number of cases, a screening mammogram will look normal even if breast cancer is present.


What you may have heard: “You’ll have to go back for more tests after your screening mammogram”

The explanation: In most cases, screening mammograms are found to be normal and no breast cancer is detected. If your mammogram shows an abnormality that requires further investigation, you will be called back for more tests.


What you may have heard: “If your screening mammogram detects a cancer, it may not be life-threatening”

The explanation: If left untreated, most breast cancers found by screening mammograms would grow and become life-threatening. However, not all those that are detected would progress to become life-threatening.

Currently, it’s not possible to tell exactly which breast cancers may become life-threatening and which may not.

Find out more about overdiagnosis


What you may have heard: “Breast density can affect the accuracy of your mammogram”

The explanation: Breasts are made up of a mixture of fat and fibroglandular (dense) tissue. Each woman’s breasts contain different amounts of these fatty and dense tissues.

In a screening mammogram, dense breast tissue appears white and so does breast cancer, which can make the cancer harder to see. There is currently no consensus about the most effective way to measure or manage breast density.

Find out more about breast density


What you may have heard: “Screening mammograms expose you to radiation”

The explanation: During your screening mammogram, your breasts are exposed to a very small amount of radiation, which is about the same amount as you get from walking around outside.

Modern mammography machines use the smallest amount of radiation possible while still obtaining high-quality x-ray pictures.


What you may have heard: “Screening mammograms are uncomfortable”

The explanation: In order to take the best image, the screening machine needs to press firmly on your breasts – without this compression, your x-ray picture would appear blurry.

Some women find this pressing uncomfortable, but it usually only lasts a few seconds.

Your female radiographer will work with you to make you feel as comfortable as possible; if you feel any discomfort, you can ask for the procedure to stop at any time.

Click here to find out more about the mammogram process

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