There has been much in the news lately regarding dense breast tissue and the concerns regarding risk of breast cancer as well as the inability of routine mammography to detect breast cancers in women with dense breast tissue.

First of all, it is important to understand what is being discussed when you hear the phrase “dense breast tissue”. The breast is normally composed of fat and glandular tissue – the higher proportion of glandular tissue to fatty tissue, the denser the breast. It is important to note that “lumpy” breast tissue is not the same as dense – density is determined by the appearance on a mammogram, not by feel. The denser your breast tissue, the more “white” will be seen on a mammogram; women with primarily fatty breasts will have a mammogram that appears darker. Digital mammograms have an easier time seeing through dense breast tissue, but all mammograms are limited in their ability to see through this dense tissue and identify cancers, as cancers usually appear as white lumps on a mammogram. Approximately 10-20% of breast cancers are missed by standard mammography – that percentage is higher in women with dense breast tissue.

It was previously thought that mammograms simply had a harder time detecting breast cancer in women with dense breast tissue. However, we now know that a woman with dense breast tissue does have an increased risk for developing breast cancer and this is the subject of intense research. There are many factors that influence breast density including age, hormone levels, genetics, age at and number of pregnancies, use of hormone replacement therapy, and overall body weight, just to name a few. And as younger women naturally have denser breast tissue, that does not mean that women in their 20’s and 30’s have an increased risk of breast cancer – in fact the risk of breast cancer increases with increasing age; it is hard to sort out when the increased risk develops.

Unfortunately, it is sometimes difficult for a woman to know if she has dense breast tissue – remember it is not the same as “lumpy” breasts. When you undergo a mammogram, the radiologist is required to make a comment regarding breast density in his or her report. However, patients often do not receive the radiologist’s report. Mammography performance and  reporting in this country is regulated by the FDA, through the Mammography Quality Standards Act, and currently it is required that patients receive a “lay letter” – a report written in layperson terms that gives a basic summary of the findings and recommendations. Your physician who ordered the mammogram will receive the official report with a notation of density.

Several states have now passed legislation requiring that patients be informed of their breast density. While I agree that patients certainly have a right to their full and un-edited test results, it is unfortunate that legislation was required to ensure that women receive their complete reports. Federal legislation is pending regarding this matter.

If you have dense breasts, what should you do?  We know that MRI, and certain forms of ultrasound, especially automated whole-breast ultrasound, can be very helpful in evaluating women with very dense breast tissue. While I do recommend these studies for some patients, it is important to note that there are no formal guidelines by either the American College of Radiology or the American Cancer Society regarding breast imaging for women with dense breast tissue, unless the woman is also considered to be in a high-risk category(due to family history for example). Some of these tests are not covered by insurance. Also realize that MRI and ultrasound also have some limitations when imaging dense breast tissue – there is no perfect method of evaluation.

Newer methods of mammography such as tomosynthesis and contrast-enhanced mammography may have some value but expose a woman to higher doses of radiation and/or a contrast material injection. In my opinion, especially for younger women with extremely dense breast tissue, automated whole-breast ultrasound shows the most promise. Unlike traditional ultrasound which is dependent on the skill and persistence of the imager or technologist, the automated system is less likely to miss areas. In addition, since the entire exam is recorded on a video system (in traditional ultrasound only selected images are saved), it can be reviewed in detail by the radiologist. Stay tuned for more information as newer imaging techniques which improve the rate of cancer detection in women with dense breast tissue are being developed.

For more information on dense breast tissue visit www.AreYouDense.Org and www.SonoCine.com