- Women over age 40 with heterogeneously dense breasts or extremely dense breasts:
- At average risk for developing breast cancer:
- 12% to 13% lifetime risk:
- Require only annual mammography
- 12% to 13% lifetime risk:
- At average risk for developing breast cancer:
- The decision to pursue additional imaging in patients with elevated risk should supplement but never entirely replace mammography
- Use of screening ultrasound or MRI of the breast are appropriate for women at increased risk:
- But the benefit remains to be determined in women of average risk for breast cancer
- Breast fibroglandular composition:
- Is defined by one of the following four descriptions:
- Almost entirely fatty
- Scattered areas of fibroglandular density
- Heterogeneously dense
- Extremely dense
- Is defined by one of the following four descriptions:
- The U.S. population distribution of breast density is as follows:
- 10% almost entirely fatty
- 40% scattered areas of fibroglandular density
- 40% heterogeneously dense
- 10% extremely dense
- Women with heterogeneously dense or extremely dense breasts:
- Are considered to have dense breasts:
- Sensitivity of mammography decreases as breast density increases
- Increased breast density not only has a masking effect, which may obscure masses:
- But also serves as an independent risk factor for breast cancer
- It has been reported that the increased risk:
- May be as much as 4 to 6-fold
- Estimates this high are obtained when comparing women with dense breasts to those with fatty replaced breasts
- Since only 10% of women have fatty replaced breasts:
- It makes more sense to make the comparison with women of average breast density
- The relative risk for cancer in women with heterogeneously dense breasts compared with the average woman is approximately 1.2, and the relative risk for cancer in women with extremely dense breasts compared with the average woman is approximately 2.1
- Are considered to have dense breasts:
- In general, breast density decreases with increasing age and increasing body mass index:
- So it is not the absolute density that is a risk factor:
- But the difference in the observed and expected density
- So it is not the absolute density that is a risk factor:
- Several states have passed legislation requiring women with dense breasts to be specifically informed of their breast density:
- Such women are informed of the limitations of mammography in dense breasts and are instructed to discuss further management with their physicians
- An informed decision regarding potential use of supplemental screening options, in addition to mammography, should be discussed, factoring in elements such as overall breast cancer risk as well as the positives and negatives of additional screening, including likelihood of additional benign biopsies
- Guidelines for enhanced screening have been developed using lifetime risk calculations as calculated by models stressing family history, such as the Tyrer Cuzick Model, and not purely using breast density
- References
- 1. D’Orsi CJ, Sickles EA, Mendelson EB, Morris EA. ACR BI-RADS® Atlas: Breast Imaging Reporting and Data System, 5th ed. Reston, VA: American College of Radiology; 2013. 2. 3. Freer PE. Mammographic breast density: impact on breast cancer risk and implications for screening. Radiographics. 2015;35(2):302-315.
- Brentnall AR, Harkness EF, Astley SM, Donnelly LS, Stavrinos P, Sampson S, et al. Mammographic density adds accuracy to both the Tyrer-Cuzick and Gail breast cancer risk models in a prospective UK screening cohort. Breast Cancer Res. 2015;17(1):147.
- American College of Radiology. ACR statement on reporting breast density in mammography reports and patient summaries. https://www.acr.org/Advocacy-and-Economics/ACR-Position-Statements/Reporting-Breast-Density. November 26, 2017. Accessed July 16, 2020.
Rodrigo Arrangoiz MS, MD, FACS, FSSO 