What is Breast Density?

The effect of breast den­si­ty on your mam­mog­ra­phy screen­ing and your over­all risk of breast cancer

Your breasts are made up of glands, ducts and fibrous tis­sue, referred to col­lec­tive­ly as fibrog­lan­du­lar tis­sue, and fat­ty tis­sue, all wrapped in skin. Dur­ing a mam­mo­gram, your radi­ol­o­gist eval­u­ates the images to deter­mine the amount of dense ver­sus fat­ty tis­sue in your breasts.

The four breast den­si­ty scores are:

A — The breasts are made up of almost all fat­ty or non-dense tissue

B — The breasts con­tain scat­tered areas of dense tis­sue but have a larg­er per­cent­age of fat­ty tissue

C — The breasts have a larg­er per­cent­age of dense tis­sue than non-dense tis­sue or het­ero­ge­neous density

D — The breasts are pri­mar­i­ly com­prised of extreme­ly dense tissue

If more than 50 per­cent of your breast tis­sue is dense, you are con­sid­ered to have dense breasts, receiv­ing either a C or D breast den­si­ty score. Dense breast tis­sue is com­mon, in fact, approx­i­mate­ly 40 per­cent of women have a C or D score, and dense breast tis­sue is not abnormal.

You may won­der why the den­si­ty of your breasts mat­ters. Dense breast tis­sue makes it more dif­fi­cult to detect tumors, and slight­ly increas­es your risk of devel­op­ing breast can­cer. Detec­tion is more dif­fi­cult because both dense tis­sue and tumors appear white on mam­mog­ra­phy imag­ing. Advance­ments in screen­ing tech­nol­o­gy, includ­ing 3D mam­mog­ra­phy, allow radi­ol­o­gists to exam­ine breast tis­sue with greater accu­ra­cy than ever before, but there is still no test that can detect breast can­cer with 100 per­cent accu­ra­cy, espe­cial­ly for those with dense breasts where addi­tion­al screen­ing tests may be helpful.

A study con­duct­ed in Novem­ber 2012 by the Radi­o­log­i­cal Soci­ety of North Amer­i­ca, found that more than 75 per­cent of women did­n’t know their breast den­si­ty score, but many of the women indi­cat­ed they would seek addi­tion­al screen­ings if they knew they had dense breasts. In order to improve aware­ness of breast den­si­ty and ensure women are aware of their breast den­si­ty score, Illi­nois passed leg­is­la­tion effec­tive Jan­u­ary of 2019, requir­ing mam­mog­ra­phy providers to noti­fy women with C or D den­si­ty scores. You can also read your breast den­si­ty in your mam­mo­gram report in MyChart.

If you are assigned a C or D score, you can speak with your pri­ma­ry care provider about your den­si­ty and your risk of breast can­cer, and dis­cuss oth­er screen­ing tests that may be help­ful. Know­ing your breast den­si­ty score, and part­ner­ing with your physi­cian to estab­lish a screen­ing sched­ule that is appro­pri­ate for you, will help you take con­trol of your breast health.

To sched­ule your annu­al mam­mog­ra­phy screen­ing, please call 1−630−545−7880.