Mammographic dense breast tissue categories affecting risk

How to find out "mammographic density" and dense breast tissue

Further Reading

  1. Detailed guide to breast cancer detection, including dense breast tissue” discussion.

Hints from a radiologist.

0% density   

You can ask for a copy of the radiologist’s report from your last mammograms. 

Sometimes the report will say whether or not the mammograms show dense breast tissue.  If the report says they are "very" dense,  then they are probably in 75% to 100% density category.  If the report says they are "somewhat" or "moderately" dense, then they are probably in the 50% to 74% category. If the report says the breasts are " entirely fatty",  they are probably in the 0% category.  If the report says they are "mostly" or "somewhat" or "partially" fatty, they are probably in the 1% to 24% category.    Note:  Some radiologists are not required to describe the mammographic density in their reports. Many radiologists do not mention anything about mammographic density, unless the density is great enough to interfere with their ability to interpret the mammograms.

What if the mammograms were taken as part of an organized screening program?

In this case, there may not be a written radiologists report,  but some screening result data must be recorded somewhere.  You can ask the screening program administrators if mammographic density is recorded in their databases.  Many (but not all) screening programs do this, and they may be able to tell you your mammographic density.

You can ask the radiologist

who reported the mammograms, to estimate your mammographic density percentage.  You can just ask “Do I have dense breast tissue?” Some radiologists would happily do this for you.  Others might be too busy or hard to reach.

You can ask to see your mammo films,

and judge for yourself.  Some mammography centers will loan you your mammograms.  Others may offer to charge you a fee to make copies of the films.  Without taking your mammograms away from the mammography center, should at least be able to look at them for free.  When you look at your mammograms you can judge the density for yourself. 
You shouldn’t worry too much making an inaccurate density measurement, because even radiologists have inter-observer agreement rates of about 0.75.  (I.e.  a radiologist estimating the density of a mammogram is likely to differ from the consensus of a group of radiologists about 25% of the time.) Its subjective.

See these examples of what mammograms look like

fatty breast
1% to 24% density
low density
25% to 49% density
50% to 74% density
moderate dense breast
75% to 100% density
dense breast tissue

A woman’s risk of breast cancer increases if her breasts are mammographically dense. You can test this using the breast cancer risk calculator..

Dr. Halls Dr. Halls
I originally made this page in year 2000, and updated the styling in 2014.

Megan Megan
Recently, some states in the USA made rules that require mammographic density to be reported on mammograms.

Dr. Halls Dr. Halls
I don’t agree with that. I think it’s bad to add verbage into mammo reports containing low-value information.

Megan Megan
Low value?, why?

Levi Levi
Suppose the report also said “she is tall, old and overweight”. Those are also risk factors and there’s nothing a woman can do to change them, or change her breast density.

Dr. Halls Dr. Halls
Organized mammographic screening programs and health insurance plans, don’t let women change their follow-up booking schedule based on those factors, so it’s wasted words.

Talking Moose Talking Moose
And doctors skim reports too quickly.

Talking Moose Talking Moose
Reminds me of a joke. I took a speed reading course and read War and Peace. It involves Russia.


My other website is where most of my breast cancer information has been accumulating.


  1. Vachon CM, van Gils CH, et al. Mammographic density, breast cancer risk and risk prediction. Breast Cancer Res. 2007 9:217.
  2. Assi V, Massat NJ, et al. A case-control study to assess the impact of mammographic density on breast cancer risk in women aged 40-49 at intermediate familial risk. Int J Cancer 2014:

A Like would be nice, or Share. For every like, I hear a bell, and smile, and you get wings.


End of page Navigation links: Additionally in: Breast Cancer.  or  Back to top