Breast ultrasound for problem of dense breasts 1024 x 683

Forty-three percent of women ages 40-74 have mammographically dense breasts. That translates to more than 25 million women in the US. The reason why this is important is that dense breasts show up as white areas on mammograms – the same as a cancer – thus, making it difficult, if not impossible in some cases, to detect cancer on routine screening.

Radiologists include information about breast density on the mammogram reports they send to the ordering physician. In fact, there is a standard way of reporting this information based on the American College of Radiology’s Breast Imaging Reporting and Data System (BI-RADS).  It is as follows:

Breast Composition Categories:

As of the BI-RADS 5th edition (2013)

  • a. The breasts are almost entirely fatty
  • b. There are scattered areas of fibroglandular density
  • c. The breasts are heterogeneously dense, which may obscure small masses
  • d. The breasts are extremely dense, which lowers the sensitivity of mammography

The problem is that until recently, most women were not told they had dense breasts in the written reports sent to notify them that their mammograms were normal.

Double Whammy

Dense mammo
A breast cancer (see white marker) is totally obscured by dense breast tissue (image from GW Univ website)

According to a recent review published in the American Journal of Roentgenology, “breast density is now established as an independent risk factor for developing breast cancer irrespective of other known risk factors.” The review goes on to say that women in the upper quartile of breast density have 4-5 times the risk of breast cancer as women in the lower quartile. So, women with dense breasts have two issues to be concerned about – one is they are at increased risk for breast cancer, the other is the “gold” standard screening exam, mammography, is less effective than in women with more fatty breasts – a double whammy.


Breast Density Legislation

After her diagnosis of stage 3C breast cancer with 13 positive lymph nodes – despite two recent normal mammograms – Nancy Cappello, PhD (a recent guest on TDWI radio) founded “Are you Dense” to advocate for legislation mandating that women be informed that if they have dense breasts to be advised that dense breasts are associated with an increased risk of breast cancer. They are also to be told that they should discuss with their doctor whether or not an additional test, such as a diagnostic breast ultrasound, should be obtained. The legislation does not, however, mandate that insurers cover the additional tests. 19 states have passed such legislation so far.


The Controversy

Although, at first blush it seems logical that all women with dense breasts should be encouraged to have an additional test to determine if they have an occult cancer, there are some issues to be considered (the first two are discussed in detail in the American Journal of Roentgenology paper discussed above):

  • Although there are many studies that show a significant number of cancers detected when women with dense breasts have further studies (ultrasound or MRI), none of these studies were limited to women with dense breasts and no other risk factors for breast cancer. So we don’t yet know how effective the additional study would be in those circumstances.
  • False positives (a study that indicates there could be a cancer when in fact there is not) lead to further testing, including biopsy. So there is the issue of morbidity to be considered.
  • Since there is no mandate to cover the cost of additional testing, some women may face an additional financial burden.
  • Finally, we don’t yet know if, as in the case of prostate cancer, there are some early stage cancers that don’t require treatment at all – that is, they are so slow growing that the woman will most likely die of a cause other than breast cancer.


A Woman’s Right to Know

The controversial issues aside, I am a firm believer in transparency in health care. It is simply a woman’s right to know whether or not her breasts are dense and whether that puts her at higher risk for breast cancer and misdiagnosis. The fact that the legislation includes a recommendation that she discuss options with her doctor reinforces the role physicians are increasingly going to be asked to play in this age of democratization of medicine: that of “Explainer-in-Chief” as well as Guide in a shared decision-making process.  Patient empowerment is here to stay…and that is a very good thing.

To learn more about the problem of dense breasts, listen to the Podcast and hear Nancy Cappello tell her story.



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