The role of breast density in breast cancer screening
Breast cancer is the most common type of cancer among women globally and – according to the WHO – impacts 2.1 million women each year globally. Early detection is important to improve the course of the disease.1
Regular screening can have a beneficial impact on clinical outcome. Women aged between 40-74 who are screened with a mammogram every 1-2 years can reduce their mortality risk by 40%.2
Current breast cancer screening options include:3,4,5
Breast MRI may reveal additional breast cancers which are missed by x-ray mammography, especially in women with high breast density.
Breast MRI often has the perception of being a long and complicated procedure, but recent studies provided evidence that a three-minute protocol might be sufficient and its sensitivity is approximately 2 to 3 times higher than that of x-ray mammography. 6, 7, 8
Breast density and breast cancer risk
Breast density impacts both breast cancer risk and the accuracy of a breast cancer screening test. Dense breasts are composed of a relatively high amount of fibro-glandular tissue, and a relatively low amount of fatty tissue.
The ability of x-ray mammography to detect breast cancer is decreased in women with dense breasts, which means cancer is more often missed or found later in advanced stages in women with dense breasts.9
In addition, women who have dense breasts have an increased risk of developing breast cancer when compared with women with fatty breasts.10
Causes of breast density 11, 12, 13
Certain factors can affect a woman’s breast density, including:
Breast density measurement
Breast density cannot be determined by either sight or clinical examination and is usually determined by x-ray mammography.14,15
Radiologists classify breast density using the Breast Imaging Reporting and Data System (BI-RADS) which includes 4 categories, ranging from almost all fatty tissue to extremely dense tissue with minimal fat.16
Breast density is an important risk factor for HCPs to consider when deciding whether a patient should have additional screening examinations.
1 Breast Cancer. https://www.who.int/cancer/prevention/diagnosis-screening/breast-cancer/en/ Accessed October 2019
2 Seely JM and Alhassan T. Screening for breast cancer in 2018 - what should we be doing today? Curr Oncol 2018; 25(S1):S115-S124
3 Screening and testing. https://www.breastcancer.org/symptoms/testing Accessed October 2019
4 Breast ultrasound. https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/breast-ultrasound.html Accessed October 2019
5 Mammogram basics. https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/mammograms/mammogram-basics.html Accessed October 2019
6 Breast MRI. https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/breast-mri-scans.html Accessed October 2019
7 Kuhl C, Weigel S, Schrading S,et al. Prospective multicenter cohort study to refine management recommendations for women at elevated familial risk of breast cancer: The EVA trial. J Clin Oncol 2010;28: 1450–145,
8 Kuhl CK, Schrading S, Strobel K, Schild HH, Hilgers RD, Bieling HB. Abbreviated breast magnetic resonance imaging (MRI): first postcontrast subtracted images and maximum-intensity projection— a novel approach to breast cancer screening with MRI. J Clin Oncol 2014; 32:2304–2310
9 Impact of breast density on the presenting features of malignancy. https://www.ncbi.nlm.nih.gov/pubmed/20853035 Accessed October 2019
10 Dense Breasts: Answers to Commonly Asked Questions. https://www.cancer.gov/types/breast/breast-changes/dense-breasts Accessed October 2019
11 Dense breast tissue: What it means to have dense breasts. https://www.mayoclinic.org/tests-procedures/mammogram/in-depth/dense-breasttissue/art-20123968 Accessed October 2019
12 What does it mean to have dense breasts? https://www.webmd.com/breast-cancer/dense-breasts#1 Accessed October 2019
13 Common variants in ZNF365 are associated with both mammographic density and breast cancer risk. https://www.nature.com/articles/ng.760 Accessed October 2019
14 Measuring breast density. https://www.news-medical.net/news/20170904/Measuring-breast-density.aspx October 2019
15 Current and Future Methods for Measuring Breast Density. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5609705/ Accessed October 2019
16 Breast Density and Your Mammogram Report. https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/mammograms/breastdensity-and-your-mammogram-report.html Accessed October 2019.