This is currently the most robust evidence on the consequences of breast density notification in Australia and highlights that notifying Australian women may have downsides in terms of the impact on health services regarding supplemental screening and, importantly, possible psychological impacts on womenBREAST density (measured on mammography) is now well established as one of several independent risk factors for breast cancer. Having dense breasts also separately increases the risk of having a breast cancer missed on mammography, thereby increasing the risk of an interval cancer between screening episodes. The sensitivity of mammography is therefore lower in women with dense breasts. It is presently estimated that at least 23% of Australian women of breast screening age have dense breasts.
Over the past decade, there has been a growing international movement to inform women about their breast density as a way to manage their breast cancer risk. Legislation in 38 US states now requires mammography services and radiologists to notify women in writing if they have dense breasts on their mammogram. This is to allow women to consider the option of supplemental screening with other modalities such as ultrasound or magnetic resonance imaging (MRI) or to consider more frequent mammographic screening.
Although on the surface density notification may be seen as a positive direction for women’s health rights and breast cancer detection, evidence to support widespread breast density notification at a population level is still lacking. The balance between benefits and harms for the individual woman in terms of short and long term outcomes remains unclear. How best to communicate this information, as well as the impact breast density notification has on primary care practitioners and health services is still being evaluated.
Underlying this is that there are no uniform recommendations or clear management guidelines to support women with dense breasts. However, a recent European consensus paper from an imaging group recommends universal density notification after a mammogram and also recommends biennial MRI screening for women with extremely dense breasts.
Although supplemental screening using ultrasound or MRI has been shown to enhance cancer detection in women with dense breasts, the effect on the rate of advanced breast cancers and mortality from breast cancer remains unclear. Additionally, there are drawbacks of supplemental screening, including a substantial frequency of false-positive results and potential overdiagnosis. Given the uncertainty about health benefit from routine supplemental screening for breast cancer in this context, these imaging tests are not government-funded so the associated costs can lead to disparities in access.
The Australian national breast screening program, BreastScreen Australia, has recently concluded that there is no evidence supporting routinely recording and notifying breast density, or providing supplemental screening to women with dense breasts. However, the potential of being informed of breast density is of interest and importance to Australian women of breast screening age. There is also growing pressure for Australian screening services to implement breast density notification as a result of the US legislation of density notification and consumer advocacy groups that believe women have the “right to know” and to participate in the decision making about management of breast density.
Where does this leave Australian women?
In our recent clinical trial, we found that when women were randomised to receive their screening mammogram result letter with breast density messaging, compared with those without, they were significantly more likely to report higher intention to seek supplemental screening (ultrasound or MRI), feeling anxious, and cancer worry. Notification also made women significantly more likely to intend to speak with their GP about the results.
This is currently the most robust evidence on the consequences of breast density notification in Australia and highlights that notifying Australian women may have downsides in terms of the impact on health services regarding supplemental screening and, importantly, possible psychological impacts on women.
Screening programs worldwide need to take these findings into account, along with previous evidence, when continuing to consider whether, and, if so, how best to implement routine notification of breast density as part of mammography screening. It seems likely that density notification will become routine in coming years and the system could prepare for this through program-embedded trials building on the evidence from our trial.
What should GPs do now?
As we’ve seen over the last few years in the US, discussing breast density and doing breast density notifications have not been straightforward and have raised challenges, particularly relating to how best to communicate breast density information and guide women toward the appropriate management strategy. Largely, this has fallen on primary care practitioners.
In Australia, we know that GPs currently have limited knowledge about breast density. Therefore, if notification were to be rolled out through population-based screening programs, GPs would require further education, support and evidence-based guidelines to have discussions with women and help manage their risk.
In the meantime, GPs could discuss breast density in the overall context of breast cancer risk. Notably, GPs can discuss modifiable risk factors or lifestyle changes related to risk, such as weight management, physical activity and alcohol consumption, which have been shown to carry similar risk to relatively non-modifiable risk factors such as breast density (here, and here). Discussions around the need for supplemental screening should include both the benefits and harms so that women can decide what is best for them.
We recommend a program-embedded randomised controlled trial to validate or refute our recent findings and evaluate both the short and long term impact that breast density notification in Australia will have on women, GPs and screening services. This will help avoid potentially unnecessary psychological and physical harms for women, reduce widening health inequalities, minimise non-beneficial use of testing, and ultimately ensure that women receive care that is based on evidence. We also recommend increased training and support for GPs about the issue of breast density and to support their discussions with women about this important health topic.
Dr Brooke Nickel is with the Sydney Health Literacy Lab at the University of Sydney, and Wiser Healthcare, also at the University of Sydney.
Professor Nehmat Houssami is with Wiser Healthcare, and The Daffodil Centre, a joint venture between the University of Sydney and Cancer Council NSW.
Associate Professor Meagan Brennan is wth the University of Notre Dame Australia School of Medicine, and the Westmead Breast Cancer Institute at Westmead Hospital.
Funding: Brooke Nickel is supported by an NHMRC Emerging Leader Research Fellowship (1194108). Nehmat Houssami is supported by a National Breast Cancer Foundation Chair in Breast Cancer Prevention (EC-21-001), and an NHMRC Investigator (Leader) Fellowship (1194410).
Conflicts of interests: None declared.
The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated.
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