I have been told that I have dense breasts on my mammograms. What does that mean?

Dense breasts mean that x-rays don’t go through the tissue easily because the tissue is dense to the x-rays.  This happens when there is not much fat in the breasts.  X-rays pass through fat very easily and cause the fat to be black on the mammogram.  Because the glandular and fibrous tissue let less of the x-rays pass through the breast, this tissue looks white on the mammograms.

This makes the sensitivity of the mammogram much less than when the tissue is fatty.

Cancer doesn’t make fat.  Consequently, it also appears white and may easily be lost in the white breast tissue when it is small.  Trying to find cancer in dense breasts is equivalent to looking for a polar bear in a snowstorm, because you are looking for a white object in a three-dimensional white background.

The picture that I have posted shows a  mammogram from two different women with cancer.  In the mammogram on the left, you can see a very small cancer against the black background of her fatty tissue.  On the right the woman has a much larger breast cancer that could not be seen because of the dense white tissue that obscures it.

The dense breast tissue, in and of itself, is not dangerous.  The danger is that if a small cancer develops, it will not be seen on the mammogram.  Mammograms are very good at recognizing cancer when there is sufficient fat present.  However, often cancers are not recognized by the mammogram in women with dense breasts before the cancer is large enough to be felt.


Print Friendly


  1. Teresa Masters
    Mar 4, 2013

    Dr. Kelly,
    Is SonoCine proper post lumpectomy? Is there a CPT code yet?
    I do need a follow up screening.
    Thank you,

    • Kevin Kelly
      Mar 5, 2013

      Yes and no.
      Yes it is ideal for following post lumpectomy on an anual basis because SonoCine is able to look through the fibrosis associated with a lumpectomy scar better than mammography alone. I’ve followed a lot of patients in your situation for up to 10 years.
      Although there is not a CPT Code yet, it is much cheaper than MRI.
      Give me a call at the Pasadena Office tomorrow before Noon if you can (626-381-9430). We’ll work something out and I’d like to see how you’re doing. I’m leaving for Vienna, Austria later tomorrow but I’ll be back Sunday evening.
      Dr. Kelly

Submit a Comment