Breast Density in Mammograms: What Do Women Need To Know?

In Malta around 300 women are diagnosed with breast cancer every year (Government of Malta, 2020). Mammography screening allows for breast cancer to be detected in its early stages therefore enhancing prognosis (Prier, 2022). One of the factors effecting the detection of early cancers is breast density. Breast density refers to proportion of fibroglandular tissue to fatty tissue seen on a mammogram. The fibroglandular tissue can make the mammogram less sensitive as it may hinder breast cancer from showing up on a mammogram (Rhodes, Radecki Breitkopf, Ziegenfuss, Jenkins, & Vachon, 2015). When the radiopaque dense breast tissue superimposes an underlying breast cancer it is known as the masking effect (Freer, 2015).

When studying for my B.Sc. (Hons) in Radiography, I wrote my dissertation titled “Evaluating the knowledge and awareness of breast density amongst Maltese Women undergoing mammography screening”. Despite the small sample size of 127 women, when analysing the results, I found that the knowledge and awareness amongst Maltese women was low and I aim to create more awareness on the topic.

According to the Breast Imaging-Reporting and Data System (BIRADS) grading system published by the American College of Radiology (ACR) in 2013, there are four different levels of breast density (D’Orsi Carl, 2013). These levels are:

• BIRADS A – Entirely fatty – Breast is made up completely of fatty tissues
• BIRADS B – Fibroglandular density – Most of the breast is made up of fatty breast tissue whilst other small parts are made up of supportive dense breast tissue.
• BIRADS C – A small part of the breast is filled less dense fatty tissue whilst most of the breast is filled with dense glandular and fibrous tissues
• BIRADS D – Extremely dense – Breast is almost entirely made up of glandular and fibrous tissue (Astley et al., 2006).

Women with high breast density are up to five times more likely to develop breast cancer than those with fatty breasts or low breast density (O’Neill, Leventhal, Scarles, Evans, Makariou, Pien, Wiley 2014). In fact, mammography is only 30% sensitive in women with extremely dense breasts whilst 80% sensitive in women with entirely fatty breasts. Therefore, making breast density a risk factor for the development of interval breast cancer (Mandelson, Oestreicher, Porter, D. White, Finder, Taplin, E. White, 2000). An interval cancer refers to a primary breast cancer detected between two screening mammograms with the last screening mammogram showing a negative malignancy (Perry, Broeders, Wolf, Tornberg, Holland, von Karsa, 2008).

The European Commission Initiative on Breast Cancer’s (ECIBC) Guidelines Development Group (GDG) updates supplementary screening recommendation guidelines yearly. The last publication stated that although more research is required on the topic of supplementary screening in breast density, the ECIBC currently does not recommend additional screening using automated breast ultrasound (ABUS), handheld ultrasound (HHUS) and magnetic resonance imaging (MRI). However, once high mammographic density has been detected, digital breast tomosynthesis is recommended (ECIBC’s Guidelines Development Group, (GDG), 2022).

In conclusion I encourage women to ask their doctors for further information regarding their own breast density and supplementary screening methods.

References:

Astley, S. M., Hufton, A., & Diffey, J. (2006). In Brady M., Rose C. and Zwiggelaar R. (Eds.), Digital mammography

D’Orsi Carl, J. (2013). Breast imaging reporting & data system. Retrieved from https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/BiRad

Freer, P. E. (2015). Mammographic breast density: Impact on breast cancer risk and implications for screening. RadioGraphics, 35(2), 302-315. doi:10.1148/rg.352140106

Goverment of Malta. (2020). Breast screening. Retrieved from https://deputyprimeminister.gov.mt/en/phc/nbs/Pages/ScreeningProgrammes/Breast-Screening.aspx

Mandelson, M. T., Oestreicher, N., Porter, P. L., White, D., Finder, C. A., Taplin, S. H., & White, E. (2000). Breast density as a predictor of mammographic detection: Comparison of interval- and screen-detected cancers. Journal of the National Cancer Institute, 92(13), 1081-1087. doi:10.1093/jnci/92.13.1081

O’Neill, S. C., Leventhal, K. G., Scarles, M., Evans, C. N., Makariou, E., Pien, E., & Willey, S. (2014). Mammographic breast density as a risk factor for breast cancer: Awareness in a recently-screened clinical sample. Women’s Health Issues : Official Publication of the Jacobs Institute of Women’s Health, 24(3), e321-e326. doi:10.1016/j.whi.2014.02.005

Perry, N., Broeders, M., de Wolf, C., Törnberg, S., Holland, R., & von Karsa, L. (2008). European guidelines for quality assurance in breast cancer screening and diagnosis. fourth edition—summary document. Annals of Oncology, 19(4), 614-622. doi:10.1093/annonc/mdm481

Prier, E. (2022). Early detection for breast cancer: Why does it matter? boise, idaho (ID), saint alphonsus. Retrieved from https://www.saintalphonsus.org/health-and-wellness/articles-for-yourhealth/early-detection-for-breast-cancer-why-does-it-matter

Rhodes, D. J., Radecki Breitkopf, C., Ziegenfuss, J. Y., Jenkins, S. M., & Vachon, C. M. (2015). Awareness of breast density and its impact on breast cancer detection and risk. Journal of Clinical Oncology, 33(10), 1143-1150. doi:10.1200/JCO.2014.57.0325

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