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Breast Density


Breast Density States: Diagnostic Imaging website

Breast density is a real hot potato at the moment! It is in the news because in certain states in the USA it is law to notify women what their breast density is. Breast density notification laws are in place in 27 states. Diagnostic Imaging Journal Website has this useful interactive map.

So, what is breast density and why is it important? Breasts are composed of supportive tissue, which is the dense tissue on mammograms and fatty tissue, which is the non-dense tissue. Dense tissue appears white on the mammogram whilst non dense tissue is grey/black. White appearances on a mammogram can be harder to see through and therefore read and interpret. White appearances can also be a sign of an abnormality.

How is it breast density measured?

Radiologists and film readers use a system call BI-RADS and use scores of between 1 and 4.

Women’s and Breast Imaging image of breast density

According to, it isn’t possible to assess breast density through clinical examination alone and scoring the mammogram to score the BI-RADs is done by a human being so subject to interpretation and error. There are various software packages available which, using a computer, claim to be able to score breast tissue more accurately. The Australian Women’s and Breast Imaging website has a useful image to demonstrate this more clearly.


Why is it considered important to know what density your breasts are?

According to the American College of Radiologists (ACR), having denser breasts can make the detection of cancers harder, therefore, if a woman has dense breasts it is important that she is told, so that she can make an informed decision regarding any further action she may wish to take. The concern is the way in which women are presented with this information. Is a letter suitable? A face to face consultation with her Doctor would be preferable, so that she has the chance to discuss what her options may be. This may work well in a country where medical treatment isn’t free at source, but in the UK, this is more problematic as we just don’t have the resources.

Australia breast screen recently released a statement regarding breast density after a number of newspaper articles were printed and more women were asking the question to mammographers during their screening visit. They state that they support discussion, public awareness and research into breast density, they will not be reporting on an individual’s breast density. They believe that there are some complex issues regarding the benefits and drawbacks of reporting of breast density that need to be evaluated. ( )

Despite searching the internet, there was nothing from the NHS Breast Screening Programme regarding their stand on the reporting of breast density at the time of writing this blog.

Why is breast density an issue?

Research suggests that increased breast density can lead to an increased breast cancer risk. Susan Komans suggests that women with very dense breasts are four to five more times likely to develop breast cancer than those with a low breast density. Breast density can be linked to a number of external factors, such as genetics, (it may run in your family), how many pregnancies you have had; the more pregnancies the less dense your breasts may be. Plus, weight; although this can be misleading. Generally, women with higher body weight have less dense breasts, therefore a lower risk of breast cancer, BUT, being overweight post menopause can increase your risk of breast cancer, so conflicting advice there.

5 measures to help reduce breast cancer risk

If you do have dense breasts, there are measures that you can take to reduce your breast cancer risk. These apply to all women as well:

  1. Eat healthily
  2. Maintain a healthy weight
  3. Exercise regularly
  4. Drink in moderation
  5. Stop smoking

In the USA they go one step further and recommend MRI and U/S to complement your yearly mammogram.

There is a twitter account in the UK called BreastDensityMatters. It is curated by a woman whose breast cancer was picked up on a routine breast ultrasound (U/S) in France, where U/S is included in the breast screening programme, but not visible on her mammogram. She is campaigning for U/S to become part of the screening programme in the UK. Not sure if that will happen with the current breast screening workforce in the UK, but, a worthwhile cause.

Ultimately, it is important to maintain a healthy lifestyle, check your breasts regularly and have your screening mammograms. If you notice anything different, go straight to your GP.

Cathy Hill suthor of blog on breast density

Cathy Hill

This blog was written by Cathy Hill, former  WoMMeN team member, who recently moved to Australia to practice mammography there.