The Impact of Breast Density on Mammography: A Radiologist's Perspective


Breast cancer is the second most common cancer in women worldwide, with mammography serving as the gold standard for early detection and diagnosis [1]. However, the sensitivity of mammography is significantly influenced by breast density. The denser the breast tissue, the more difficult it becomes to detect malignancies [2]. This article will explore the implications of breast density on mammography results, patient communication, and the evolving landscape of breast density laws.

The Effect of Breast Density on Mammography Results

Breast density refers to the proportion of fibroglandular tissue to fatty tissue in the breast [3]. Women with denser breasts have a higher proportion of fibroglandular tissue, which can mask or mimic malignancies on a mammogram due to its similar radiographic appearance [2].

High breast density can lead to a phenomenon known as "masking effect", reducing the sensitivity of mammograms [4]. This is because both dense breast tissue and cancerous cells appear white on mammograms, making it challenging to distinguish between them. Consequently, the chances of false-negative results increase, potentially leading to delayed detection and treatment of breast cancer [5].

Communication with Patients About Breast Density

Effective communication about breast density is vital for patients to understand their risk and make informed decisions about their healthcare. As a radiologist, here are some tips for communicating with patients:

  1. Explain the Concept: Clearly explain what breast density is and how it affects the interpretation of mammograms. Use visual aids if possible, to help patients understand the concept better.

  2. Discuss the Risks: Inform patients about the dual risk associated with dense breasts - the increased risk of developing breast cancer and the potential for cancers to be missed on mammograms.

  3. Discuss Supplemental Screening Options: Depending on the risk factors, additional imaging tests like ultrasound or MRI may be suggested. Make sure to explain the benefits and potential drawbacks of each of these tests.

  4. Personalized Approach: Every woman’s situation is different. Tailor your discussion to fit the individual patient’s risk factors, personal and family history.

Future Implications of Breast Density Laws

The implications of breast density have led to the enactment of laws in several states across the U.S., mandating that women be notified about their breast density following a mammogram. Known as Breast Density Notification laws, they aim to increase awareness and inform women about the potential need for additional screening [6].

However, these laws vary significantly across states, leading to inconsistencies in how women are informed about their breast density. Moving forward, a standardized approach is necessary to ensure that all women receive the same quality of care and information [7].

Moreover, the future of breast density laws may also influence the development and adoption of newer imaging technologies. Advanced tools like automated breast ultrasound (ABUS) and digital breast tomosynthesis (DBT) can improve cancer detection in dense breasts [8]. As laws continue to evolve, they could potentially drive increased use of these technologies.

Breast density significantly impacts the effectiveness of mammograms, necessitating clear communication with patients and potentially influencing breast density legislation. As a radiologist, staying informed about these developments is crucial to providing optimal patient care and advocating for improved breast cancer screening policies.


[1] American Cancer Society. Breast Cancer Facts & Figures 2019-2020. Atlanta: American Cancer Society, Inc. 2019.

[2] Boyd NF, Guo H, Martin LJ, et al. Mammographic density and the risk and detection of breast cancer. N Engl J Med. 2007;356(3):227-236. doi:10.1056/NEJMoa062790

[3] Martin LJ, Boyd NF. Mammographic density. Potential mechanisms of breast cancer risk associated with mammographic density: hypotheses based on epidemiological evidence. Breast Cancer Res. 2008;10(1):201. doi:10.1186/bcr1831

[4] Sprague BL, Gangnon RE, Burt V, et al. Prevalence of mammographically dense breasts in the United States. J Natl Cancer Inst. 2014;106(10). doi:10.1093/jnci/dju255

[5] Kerlikowske K, Zhu W, Tosteson ANA, et al. Identifying women with dense breasts at high risk for interval cancer: a cohort study. Ann Intern Med. 2015;162(10):673-681. doi:10.7326/M14-1465

[6] Rhodes DJ, Radecki Breitkopf C, Ziegenfuss JY, Jenkins SM, Vachon CM. Awareness of breast density and its impact on breast cancer detection and risk. J Clin Oncol. 2015;33(10):1143-1150. doi:10.1200/JCO.2014.57.0325

[7] D'Orsi CJ, Sickles EA, Mendelson EB, Morris EA. ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System. Reston, VA, American College of Radiology; 2013.

[8] Skaane P, Bandos AI, Gullien R, et al. Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration. Eur Radiol. 2013;23(8):2061-2071. doi:10.1007/s00330-013-2820-3