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Breast Density

BreastScreen NSW uses software to report breast (mammographic) density to clients and their nominated GP.

What is breast density?

Breasts are made up of fatty tissue and fibroglandular (dense) tissue, which includes milk ducts, milk glands and supportive tissue. Breast density is the ratio of dense tissue to fatty tissue. It cannot be felt or assessed by a physical examination and isn't related to breast size or shape.

Breast density is only reported on a mammogram and is commonly referred to as mammographic density. For most women, breast density changes over time and decreases as you get older.

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All women, including those with dense and extremely dense breasts, are recommended to have their regular breast screens (mammograms).

Why breast density matters

Breast density can mask or hide cancers because dense tissue and breast cancers both appear white on a breast screen (mammogram). This can make it more difficult to see a cancer in the breast when you have your breast screen.

Higher breast density is linked with a higher risk of developing breast cancer and the size of this risk increases with increasing density.

Your breast density report

BreastScreen NSW uses software to report breast density. Our clients and their nominated GP are provided with a density report in their screening result letter, which is accompanied by a breast density factsheet.

The Breast Imaging Reporting and Data System (BI-RADS) is a classification system used to describe four categories of breast density. Clients will receive one of the categories below:

Category A

(least dense)

category a least dense mammogram

BI-RADS category A:

The breast tissue is almost entirely fatty and not dense.

Category B

category b mammogram

BI-RADS category B:

The breast tissue is mostly fatty tissue with some scattered areas of
fibroglandular density. The breast tissue is not dense.

Category C

category c mammogram

BI-RADS category C:

The breast tissue is mostly fibroglandular tissue with some areas of fatty tissue. The breast tissue is dense.

Category D

(most dense)

category d most dense mammogram

BI-RADS category D:

The breast tissue is almost all fibroglandular tissue and is extremely dense.

No breast density category determined: In a small number of cases a density category cannot be determined due to technical reasons. This does not affect the breast screen result.

Breast density of clients who have attended BreastScreen NSW⁵⁶³⁴

15% of women are Category A
45% of women are Category B
35% of women are Category C
5% of women are Category D

Pie chart distribution of breast density categories

What action should I take if I have dense breasts?

We encourage women who have questions or concerns about their breast density or breast cancer risk to speak with their GP.

Have regular mammograms

Routine mammography is recommended for women aged 50 – 74 years (40 – 74 years for Aboriginal and Torres Strait Islander women), including those with dense breasts.
High breast density alone does not categorise patients as at high risk of breast cancer, as other factors must be considered.

Learn more about your breast cancer risks

risk icon

Having dense breasts is common and normal and just one risk factor for breast cancer. It’s important to consider all of the risk factors such as age, family history, and genetic variants; and modifiable risk factors such as diet, weight, alcohol intake, menopausal therapy, and exercise.
Click to find more information on modifiable risk factors (things you can change) and non-modifiable risk factors (things you can't change).
You can also learn more about your individual breast cancer risk by completing a risk assessment which will give you a report that can provide the basis for discussions between you and your doctor about your individual breast cancer risk, prevention and management.

The need for additional tests (supplemental screening)

Everyone’s circumstances are unique. For most women, having additional tests won’t be necessary however we recommend having a discussion with your doctor, especially if you have other risk factors. Additional tests may include:

Magnetic Resonance Imaging (MRI) - a scan that uses strong magnetic fields and computer generated radio waves to produce detailed pictures of the inside of the body.
Breast Ultrasound - a scan that creates a real-time picture of the inside of the body using sound waves.
Digital Breast Tomosynthesis (DBT) - uses x-rays the same as 2D mammograms. The x-rays are used at multiple angles to provide a series of pictures of the breast and can create a 3D image of the breast.
Contrast-enhanced mammography (CEM) - combines breast x-rays (mammograms) with intravenous contrast (x-ray dye the same as the dye used for CT scans) to produce pictures of the breasts.

Additional tests are not currently provided as part of the BreastScreen NSW program, require a referral from a GP and come at a cost with limited Medicare rebate. Presently, there is no agreement in Australia or internationally on the optimal pathway for those with increased breast density, in part because what is appropriate for any individual woman will depend on other risk factors, as well as personal circumstances and preferences. There is currently no clear evidence to prove additional tests are beneficial or essential for women with dense breasts. In some cases, they can lead to false positives (increase in breast biopsies with benign outcomes) and the need for more tests.

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Breast density FAQs

Breast density is not related to the look, feel or size of the breast. It cannot be felt or assessed by a physical examination. Some women experience heavy and lumpy breasts and this can be normal for them.

BreastScreen NSW encourages all women to be breast aware. Any new or concerning breast changes such as a lump, dimpling, nipple discharge or breast pain should be reported to a doctor as soon as possible for appropriate investigation.

Yes. Younger women generally have more dense breasts compared to older women. Breast density usually reduces with age, particularly after menopause.

Breast density is also influenced by other factors including genetics, Body Mass Index (a lower BMI is associated with higher breast density), having had children (may decrease breast density), hormone replacement therapy (may increase breast density), and anti-estrogen therapy (may decrease breast density).

If you are concerned about a change in your breast density report, please speak to your GP.

Breast density can be familial (run in the family) however the only way to really know your breast density is to have a mammogram.

In a small number of cases software used to report breast density cannot determine a reading due to technical reasons. Unless the issue persists, your breast density will be measured at your next BreastScreen NSW appointment. We won’t repeat your breast screen if the software can’t report your breast density as it may unnecessarily expose you to additional radiation. Speak to your doctor if you have any questions or concerns about this.

It can, depending on the type of implant you have. Please tell our staff when you book if you have implants or have had breast enhancement injections, and our radiographer will discuss this with you at your appointment.

It can, depending on the type of device you have. Please tell our staff when you book if you have a medical device in your chest and our radiographer will discuss this with you at your appointment.

Breast density can be influenced by hormone treatment.
Reading of mammograms can be impacted by surgical procedures due to the presence of scar tissue.

BreastScreen NSW recommends clients speak with their specialist or doctor if they have questions about their breast density.

BreastScreen NSW commenced recording breast density on 7 April 2025. Clients who screened prior to this date will receive a breast density report at their next breast screen. If you have any questions or concerns, please speak with one of our staff.