Research: Dense Breast Tissue Eclipses Other Known Risk Factors

A recent Breast Cancer Surveillance Consortium study concludes that breast density exceeds other risk factors, including obesity, family history, and later in life childbirth. The population-based, case-control, cohort study included 202,746 women.

The authors found that breast density was the most prevalent risk factor and that 39.3 percent of breast cancers in pre-menopausal women and 26.2 percent in post-menopausal women had the potential to have been prevented if all women with higher breast density, BI-RADS categories C and D, had been shifted to lower-density BI-RADS category B.

“The most significant finding in this study is the impact of breast density on development of breast cancer in the population,” said senior author Karla Kerlikowske, MD, professor of medicine and of epidemiology and biostatistics in the UCSF Helen Diller Family Comprehensive Cancer Center.

A recent Nancy's Chalkboard Blog Post featured this important study - Fake News:  Having Dense Breast Tissue is No Big Deal.

Take Away:  Talk to your health care providers about your breast tissue composition. If you have dense breast tissue (BIRADS C or D) ask your docs about added screening (such as ultrasound or MRI) to your 2D or 3D mammography.  The impact of dense breast tissue is critical to a woman's breast health - she is at a higher risk of breast cancer in addition to a greater risk of having cancer invisible by 2D or 3D mammogram because of her dense breast tissue.  Invisible cancers that go undiagnosed by screening are often larger invasive cancers that have travelled to lymph nodes and confer worse survivor outcomes.

Abstract of the study is here.


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  • Are You Dense? Fact #1:

    Breast density is one of the strongest predictors of the failure of mammography screening to detect cancer.

  • Are You Dense? Fact #2:

    Two-thirds of pre-menopausal women and 40% of post-menopausal women have dense breast tissue. 

  • Are You Dense? Fact #3:

    Adding more sensitive tests to mammography significantly increase detection of invasive cancers that are small and node negative.

  • Are You Dense? Fact #4:

    American College of Radiology describes women with "Dense Breast Tissue" as having a higher than average risk of Breast Cancer.

  • Are You Dense? Fact #5:

    While a mammogram detects 98% of cancers in women with fatty breasts, it finds only 48% in women with dense breasts.

  • Are You Dense? Fact #6:

    A woman at average risk and a woman at high risk have an EQUAL chance of having their cancer masked by mammogram.

  • Are You Dense? Fact #7:

    Women with dense breasts who had breast cancer have a four times higher risk of recurrence than women with less-dense breasts.

  • Are You Dense? Fact #8:

    A substantial proportion of Breast Cancer can be attributed to high breast density alone.

  • Are You Dense? Fact #9:

    Cancer turns up five times more often in women with extremely dense breasts than those with the most fatty tissue.

  • Are You Dense? Fact #10

    There are too many women who are unaware of their breast density, believe their “Happy Gram” when it reports no significant findings and are at risk of receiving a later stage cancer diagnosis.