How to find out the "mammographic density" of your breasts.

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 breasts are mammographically dense.  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:  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.  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
mild
 
50% to 74% density
moderate
 
75% to 100% density
dense breasts

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

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