Citation, DOI & article data
Breast density refers to the amount of fibroglandular tissue in a breast relative to fat. It can significantly vary between individuals and within individuals over a lifetime.
- a: the breasts are almost entirely fatty
- b: there are scattered areas of fibroglandular density
- c: the breasts are heterogeneously dense, which may obscure small masses
- d: the breasts are extremely dense, which lowers the sensitivity of mammography
Compared to the previous edition, the estimation of dense tissue percentages were replaced by a description of subjectively estimated breast density associated with changes in the sensitivity of mammography, since the effect of percentage breast density as an indicator for breast cancer risk takes on a greater importance compared to the masking effect of dense fibroglandular tissue on mammographic depiction of noncalcified lesions 1.
An optional description of the location of densities can be included as a second sentence for the scattered and heterogeneous categories. The radiologist is encouraged to assign a category based on the concern that areas of dense fibroglandular breast tissue could mask underlying cancer 3.
There are analogous BI-RADS categories for the amount of fibroglandular tissue on breast MRI:
- almost entirely fat
- scattered fibroglandular tissue
- heterogeneous fibroglandular tissue
- extreme fibroglandular tissue
Breast density assessment is qualitative and subject to interobserver variability 4.
For other classifications of historical significance, see the article on parenchymal patterns in breast imaging.
In dense breasts, the incidence of invasive ductal carcinoma is higher than in other groups of breast density, likely as a combination of the amount of gland present as well as possible observation error due to the lower sensitivity of detection.
The use of density determination is now mandatory in some states in the United States, and patients must be informed of the fact that they have "dense" breasts, which usually is defined as heterogeneously dense or extremely dense.
In dense breasts, screening ultrasound is potentially beneficial. Contrast-enhanced MRI is also advocated as an adjunct to screening mammography in extremely dense breasts; however, no large data is available in this regard. The DENSE Trial is undergoing to evaluate MRI as an additional screening tool in women aged 50-75 years with extremely dense breasts 5.
Factors that can increase breast density
- hormone replacement therapy: the effect is greater with combination hormone therapy than with estrogen therapy alone 6
- weight loss (from a reduction of breast fat)
- breast cancer: especially inflammatory breast cancer
- inflammation: mastitis
Factors that can decrease breast density
- age, postmenopausal state
- medications, e.g. danazol
- vitamin D and calcium intake in pre-menopausal women
- increasing age
- weight gain
- acromegaly 7
- 1. D’Orsi CJ, Sickles EA, Mendelson EB, Morris EA, et al. ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System. Reston, VA, American College of Radiology; 2013. ISBN:155903016X. Read it at Google Books - Find it at Amazon
- 2. Pesce K, Orruma MB, Hadad C, Bermúdez Cano Y, Secco R, Cernadas A. BI-RADS Terminology for Mammography Reports: What Residents Need to Know. (2019) Radiographics : a review publication of the Radiological Society of North America, Inc. 39 (2): 319-320. doi:10.1148/rg.2019180068 - Pubmed
- 3. Winkler NS, Raza S, Mackesy M, Birdwell RL. Breast density: clinical implications and assessment methods. (2015) Radiographics : a review publication of the Radiological Society of North America, Inc. 35 (2): 316-24. doi:10.1148/rg.352140134 - Pubmed
- 4. Sprague BL, Conant EF, Onega T, Garcia MP, Beaber EF, Herschorn SD, Lehman CD, Tosteson AN, Lacson R, Schnall MD, Kontos D, Haas JS, Weaver DL, Barlow WE. Variation in Mammographic Breast Density Assessments Among Radiologists in Clinical Practice: A Multicenter Observational Study. (2016) Annals of internal medicine. 165 (7): 457-464. doi:10.7326/M15-2934 - Pubmed
- 5. Emaus MJ, Bakker MF, Peeters PH, Loo CE, Mann RM, de Jong MD, Bisschops RH, Veltman J, Duvivier KM, Lobbes MB, Pijnappel RM, Karssemeijer N, de Koning HJ, van den Bosch MA, Monninkhof EM, Mali WP, Veldhuis WB, van Gils CH. MR Imaging as an Additional Screening Modality for the Detection of Breast Cancer in Women Aged 50-75 Years with Extremely Dense Breasts: The DENSE Trial Study Design. (2015) Radiology. 277 (2): 527-37. doi:10.1148/radiol.2015141827 - Pubmed
- 6. Chen FP, Cheung YC, Soong YK. Factors that influence changes in mammographic density with postmenopausal hormone therapy. Taiwan J Obstet Gynecol. 2010;49 (4): 413-8. doi:10.1016/S1028-4559(10)60091-5 - Pubmed citation
- 7. Tagliafico A, Calabrese M, Tagliafico G et-al. Increased mammographic breast density in acromegaly: quantitative and qualitative assessment. 2010;doi:10.1530/EJE-10-0896 - Pubmed citation