Purpose: Dense breast tissue is an independent risk factor for breast cancer and lowers the sensitivity of screening mammography. Supplemental screening with ultrasound or MRI improves breast cancer detection rate but has potential harms. Breast density notifcation (BDN) legislation has been introduced in the United States (US) and its impact on supplemental screening practice is unclear. This study systematically reviewed current evidence to explore the impact of BDN on supplemental screening practice in the US.

Methods: Medline, PubMed, Embase, Cochrane and the Cinhal Library databases were searched (2009-August 2020). Studies were assessed for eligibility, data were extracted and summarised, and study quality was evaluated.

Results: Evidence from the included studies (n=14) predominantly showed that BDN legislation increased the overall utilisation of supplemental screening by 0.5–143%. This effect was amplified if the notification included a follow-up telephone call informing women about additional screening benefits, and if the state’s law mandated insurance cover for supplemental screening. Likelihood of supplemental screening was also influenced by history of breast biopsy and family history of breast cancer, race, age, socioeconomic status, density category, and physician’s specialty and region. Some studies reported increases in biopsy rate (up to 4%) and cancer detection rate (up to 11%) after implementation of BDN legislation.

Conclusion: BDN leads to increased use of supplemental screening. This has implications for women and the health system. These findings can help inform current and future screening programs, where breast density notification is currently implemented or being considered.


breast density, mammography, notification, legislation, supplemental screening

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