What are dense breasts?
Breasts are made up of a mixture of glandular breast tissue, connective tissue, and fat. High breast density means there is a greater amount of glandular and connective tissue compared to fat. Breast density is not a measure of how the breasts feel, but rather how the breasts look on a mammogram. Dense tissue can show up as white areas on the x-ray. Breast cancers also show up as white areas on x-rays. This makes breast cancer more difficult to detect in dense breasts.
Image courtesy of BreastScreen WA.
Breast density is rated on a scale from very to low to extremely dense. About 1/3 of women undergoing breast screening have dense breasts.
It's not clear why some women have dense breast tissue and others do not. You may be more likely to have dense breasts if you are younger, pre-menopausal, or taking Hormone Replacement Therapy (HRT) . As you age, the amount of glandular breast tissue in your breasts decreases and is replaced by fat. Your breasts may become less dense as you age though some women continue to have dense breast tissue throughout their life.
Dense breast tissue makes breast cancer screening less accurate, and it may increase the risk of breast cancer. Women with dense breasts should have regular breast screens. A breast screen is the only screening test proven to reduce breast cancer deaths.
BreastScreen Victoria is currently undertaking research to identify the best way to reliably measure breast density. We are also studying the link between breast density and breast cancer risk to develop pathways for managing women with dense breasts. Until BreastScreen Victoria is confident of the most reliable way to measure breast density, we will not be reporting on an individual women's breast density.
We recommend that you continue to have regular breast screens as the best way of monitoring for any change in breast tissue.
If you are concerned about breast density, you can call Cancer Council Victoria on 13 11 20 to talk to a cancer nurse.
Frequently asked questions
Dense breast tissue makes breast cancer screening less accurate, and it may increase the risk of breast cancer.
Having dense breasts affects you in two ways:
- Increases the chance that breast cancer may go undetected by a breast screen. Breast cancers, which look white like breast tissue, are easier to see on a mammogram when they are surrounded by fatty tissue, which looks dark.
- Increases your risk of breast cancer. Women with extremely dense breast tissue (a low proportion of fat) are four to five times more likely to get breast cancer than women with low breast density.
Yes. A breast screen is the only screening test proven to reduce breast cancer deaths. Having a breast screen every two years is currently the most effective way to detect breast cancer early in women showing no symptoms who are over 50 regardless of their breast density.
Currently, there are no screening guidelines that include tests other than mammograms for women with dense breasts.
3-D mammogram (breast tomosynthesis), breast ultrasound, and breast MRI (each in combination with mammography) are being studied to learn whether they improve detection in women with dense breasts compared to mammography alone.
You and your doctor may consider additional or supplemental testing based on your other risk factors and your personal preferences.
BreastScreen Victoria recognises that breast density has an important effect on breast screening. Increased breast density is associated with an increased risk of breast cancer while leading to a lower accuracy or 'sensitivity' for cancer detection.
BreastScreen Victoria is currently undertaking research into breast density to understand:
- how to reliably measure breast density
- the link between breast density and breast cancer risk
- pathways for managing women with dense breasts