Breast Density: How Dense Are You?



Only in America can we find a way to scare the bejesus out of a woman with normal breasts and a normal mammogram. But that’s exactly what breast density notification laws in about half the states, including Pennsylvania and New Jersey, are doing.

I know this all too well because I receive the letter telling me: “Your mammogram shows that your breast tissue is dense.  Dense breast tissue is very common and is not abnormal…but can make it harder to find cancer on a mammogram and may also be associated with an increased risk of breast cancer.  Talk to your doctor about your own risks for breast cancer.” Geez!!!!

The information mandated by the law is just enough to scare any women who happens to have dense breasts, but not enough to help her understand what this really means.

If you’ve gotten such a letter, don’t be afraid.  Having dense breasts is normal, especially if you are under age 60.  Here’s what you need to know according to Margaret Polaneczky, an obstetrician-gynecologist at Weill Cornell Medical College and N.Y. Presbyterian Hospital. She recently wrote for the Diagnosis: Cancer blog at I found her information to be sooooooooooooo helpful.

Breast density is a technical term, not an abnormal diagnosis. It describes how well X-rays pass through breast tissue.  It is a surrogate for how much of the breast is fatty and how much is glandular.

Breast density is subjective. Different radiologists may assign the same mammogram different density ratings.

Breast density can vary across a woman’s menstrual cycle and over her lifetime. That means that the same woman, scanned at a different time in her cycle or at a later year, may or may not be told she has dense breasts.

Increased breast density may be a risk factor for getting breast cancer. The mechanism is unknown, but it could be that breast density is just the end result of other factors that increase breast cell proliferation and activity factors such as genetics and postmenopausal hormone use.

We really have no way to translate individual breast density into individual breast cancer risk.  But the biggest problem with considering breast density as a risk factor for breast cancer is that most women at some point in their lives have dense breasts.

Dense breasts can obscure a cancer on mammogram. Overall, about 10 percent of breast cancers are missed by mammograms. (Mine was missed. I pleaded for an ultrasound…sorry, I digress). That percentage may be higher if a woman has dense breasts. (Umm…hello). The exact miss rate depends on her risk to start with, which depends on age and other risk factors.

Additional screening beyond mammography is recommended only for women at highest risk for breast cancer. Even in this group, declines in mortality with additional screening have not yet been shown, and the rate of false alarms with this additional testing is extremely high. (My opinion…you know your body, get a second, third or fourth opinion. I got five. Just sayin’).

What should you do if you’ve been told your breasts are dense on mammography? If you are at increased risk for breast cancer due to personal or family history, you may want to consider adding ultrasound or MRI screening. (Yes!!!!)!

If you are not at increased risk for breast cancer and have dense breasts, there is no recommendation that you do anything other than continue screening at whatever interval you and your doctor have decided is right for you.  If you decide you nonetheless want an ultrasound, understand that you will need to accept the additional false positives and biopsies that may result and that the additional screening has not been shown to decrease deaths from breast cancer in women at average risk. (On the other hand, getting more than one or two opinions may be very beneficial…just say’n….again).

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