Dense Breast Tissue

How did a mammogram as a screening tool fail me?

From the Susan G. Komen for the Cure website I found the following definition:

High Breast Density on Mammogram

“Studies show that as breast density increases, so does the risk of breast cancer. Breast density refers to the proportions of fat and tissue in the breasts as seen on a mammogram. High density breasts are those that have a greater proportion of tissue than fat. Low density breasts have a greater proportion of fat than tissue. Women with very dense breasts, as assessed by mammography, are four to five times more likely to develop breast cancer than women with low density breasts.

Although these findings have been consistent, health care providers do not yet regularly use a woman’s breast density to assess her breast cancer risk. This is mainly due to the lack of an agreed-upon standard for assessing breast density.”

Breast Density research and news links (most recent and/or relevant) (Breast Cancer Risk: A screening 3x more effective than mammograms. “Breast cancer screening should be individualized depending on breast density.”  1/2011 )    (Dr. Oz 10/2010) (Breast Cancer risk linked to density 10/2010) (MBI three times as effective as mammo in dense tissue 11/16/2010) (Breast density linked to higher breast cancer risk  10/7/2010)  Susan G. Komen for the Cure® Advocacy Alliance Warns of Increased Risk and Flaws of Mammography for Women with Dense Breasts (10/2010) (Washington Post 10/2010) (New Imaging tools address challenges of dense breast tissue  10/2010)  Are You Dense? (actress Fran Drescher’s webite 7/2010) (More magazine 8/2010) (Breast density linked to cancer risk  6/21/2010) (Breast Cancer Density Provides Clue to Cancer Risk, 6/25/2010) (The importance of breast density  6/23/2010) (Woman’s Doc: Know Your Breast Density 6/2010)  (ACR Member Discusses Breast Density, ACR website) (Molecular Breast Imaging-Seeing Cancer Tumors  3/2010) (Breast Cancer Screening: Age or Density? Inside Cancer Website 4/29/2010) )  Why do women with dense breasts have more breast cancer? 12/2008) (Reseachers call breast density a cancer risk ignored. NY Times 2/2007)  (2007) (Dr. Deborah Rhodes, Mayo Clinic. MBI study and politics of breast imaging and its implications for women with dense breasts.  1/2011)  (MBI three times as effective as mammo in dense tissue 11/16/2010) (Mayo Clinic Finds High Breast Density Increases Breast Cancer RISK 10/29/10) Breast Density linked to higher breast cancer risk, (10/4/2010, Epidemiology, Biomarkers, and Prevention, journal of the AACR) (Women in Their Forties Have Lower Mammographic Tumor Detectability 7/2010, research from: Journal of the National Cancer Institute)–media/aacr-press-releases.aspx?d=1964 (Mammographic Density and Risk of Breast Cancer. Study by: American Association for Cancer Research 4/21/2010) (NBC News video re: density linked to risk) (Automated Ultrasound improves cancer detection. Study: European Congress of Radiology 3/5/2010) 1/2010 Journal of the ACR, “Breast Cancer Screening with Imaging” (Dense Tissue May Promote Tumor Cell Invasiveness . Vanderbilt-Ingram Cancer Center Study 9/9/2008) (Study: The Journal of the American Medical Association, May 2008)  (Mammographic Density and the Risk and Detection of Breast Cancer, New England Journal of Medicine 2007) (Dense breast tissue risk factor for cancer. Source: New England Journal of Medicine 1/1/2007) (Research; Mammo sensitivity decline with increasing density . Study reported: Radiology 10/2002)

Research Studies:

  1. ACRIN666 Study – Data published in the Journal of the American Medical Association in 2008 from the American College of Radiology Imaging Network (ACRIN) 6666 trial showed that not only do more than half of women younger than 50 have dense breast tissue (as do one-third of women older than 50), mammography’s sensitivity for women with dense breast tissue can be as low as 30% to 48%, with higher interval cancer rates and worse prognosis for the resulting clinically detected cancers. StudyAbstract:   ACRIN6666 FAQ: http://www.­acrin.­org/­Portals/­0/­Protocols/­6666/­recruit_and_educ­ation/­6666FAQ05-­01-­08Final.­doc 
  2. Breast Tissue Composition and Susceptibility to Breast Cancer, Norman F. Boyd, Lisa J. Martin, Michael Bronskill, Martin J. Yaffe, Neb Duric, Salomon Minkin, Manuscript received October 9, 2009; revised May 11, 2010; accepted May 28, 2010
  3. 10.2010 Annals of Surgical Oncology. Impact of Breast Density on the Presenting Features of Malignancy. Sloan Kettering Research
  4. 8.2010 Oxford UniverPress, Breast Tissue Compositonand Susceptibility to Breast Cancer
  5. 5.2010 Cancer, Epidemilogy,Bimarkers&Prevention, Research Article
  6. Effect of Baseline Breast Density on Breast Cancer Incidence,
  7. Stage, Mortality, and Screening Parameters: 25-Year
  8. Follow-up of a Swedish Mammographic Screening

How to find out the “mammographic density” of your breasts.

Hints from a radiologist.

0% density   

You can ask for a copy of the radiologist’s report from your last mammograms. 

Sometimes the report will say whether or not the breasts are mammographically dense.  If the report says they are “very” dense,  then they are probably in 75% to 100% density category.  If the report says they are “somewhat” or “moderately” dense, then they are probably in the 50% to 74% category. If the report says the breasts are ” entirely fatty”,  they are probably in the 0% category.  If the report says they are “mostly” or “somewhat” or “partially” fatty, they are probably in the 1% to 24% category.    Note:  Radiologists are not required to describe the mammographic density in their reports. Many radiologists do not mention anything about mammographic density, unless the density is great enough to interfere with their ability to interpret the mammograms.

What if the mammograms were taken as part of an organized screening program?

In this case, there may not be a written radiologists report,  but some screening result data must be recorded somewhere.  You can ask the screening program administrators if mammographic density is recorded in their databases.  Many (but not all) screening programs do this, and they may be able to tell you your mammographic density.

You can ask the radiologist

who reported the mammograms, to estimate your mammographic density percentage.  Some radiologists would happily do this for you.  Others might be too busy or hard to reach.

You can ask to see your mammo films,

and judge for yourself.  Some mammography centers will loan you your mammograms.  Others may offer to charge you a fee to make copies of the films.  Without taking your mammograms away from the mammography center, should at least be able to look at them for free.  When you look at your mammograms you can judge the density for yourself.  You shouldn’t worry too much making an inaccurate density measurement, because even radiologists have inter-observer agreement rates of about 0.75.  (I.e.  a radiologist estimating the density of a mammogram is likely to differ from the consensus of a group of radiologists about 25% of the time.) Its subjective.

See these examples of what mammograms look like

fatty breast
1% to 24% density
low density
25% to 49% density
50% to 74% density
75% to 100% density
dense breasts

A woman’s risk of breast cancer increases if her breasts are mammographically dense. You can test this using the breast cancer risk calculator.


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