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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
BREAST 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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So the argument is that GPs shoild not tell patients they have dense breasts, a recognised risk factor for breast cancer, because they might worry and seek a breast ultrasound which is known to be a useful adjunct in the diagnosis of breast cancer, especially with dense breasts. Bur we are telling women to have earlier screening if there is a family history of breast cancer. I cannot see the difference. There must be transparency in health care.
We agree that the emphasis should be on improving women’s health and well being. While mammographic screening has proven benefits, not all women benefit equally. The denser the breast, the less the benefit. “Non-beneficial use of testing” may include mammography in many women with dense breasts as cancers are often hidden. Dense tissue also increases the risk of developing breast cancer.
MRI is not limited by breast density and detects many more early breast cancers than mammography, is proven to reduce late-stage disease in high-risk women, and can be performed at relatively low cost. That is why there is a new European Society of Breast Imaging recommendation to include screening MRI, perhaps instead of mammography, in women with extremely dense breasts. The same benefit likely extends to women with heterogeneously dense breasts, but a shortage of MRI equipment/access make that impossible to implement on a wide scale at present. Contrast-enhanced mammography (CEM) may have similar benefit to MRI and is easier to implement, but further studies are warranted.
In the USA, based on http://www.DenseBreast-info.org legislative analysis, 38 states and the District of Columbia (DC) require some form of density notification to women with their mammography results (https://densebreast-info.org/legislative-information/state-legislation-map/). Unfortunately, not all of these laws require informing a woman that her own breasts are dense. Fourteen states (including DC) require insurance coverage for screening MRI for at least some women with dense breasts (often with family history or other risk factors).
Women should be given the choice to pursue adequate breast screening. Women participate in screening in the hope that cancer, if present, will be found early. Women should have access to screening that can confidently assure that there is no cancer present. It is irresponsible not to provide such screening, particularly under the guise of protecting women from the “stress” caused by confusion on the part of the healthcare system. Further studies should focus on providing education to women and their providers on dense breasts and on evidence collection during implementation of supplemental (or replacement) screening with MRI, CEM, or ultrasound where MRI or CEM are not possible.
Have been there with the dense breasts and cancer not visible on breast screen ultrasound. Now really “ enjoying” chemotherapy and immunotherapy having had surgery. This will be followed my radiotherapy There needs to be more awareness about density as an independent risk factor for breast cancer and the unreliability of mammogram alone in dense breasts. Costs of other screening modalities need to be weighed against treatment and absenteeism costs for this increasingly common disease
Why the focus on survival only, and not consider the risk of more aggressive treatment required when a cancer is detected late because of density? A cancer detected later, because it was hidden in a dense breast and undetected by BreastScreen’s 2D m/m and factory-farm reading conditions, may require chemotherapy and/or 30x radiation treatments instead of the shorter hypofractionated course.
Survival isn’t the only consideration for patients. Intensity of treatment ranks highly too.
Since it is almost impossible to get mental health care from the public system or form other professionals at a reasonable cost it falls to GPs to provide the backbone of care. We are often well placed to do so, as we have our patients for many years, they have easy access to us, and I fo one often bulk bill my most needy patients. Sometimes the GP is the one constant in their lives.