Breast density, a viewpoint in JAMA

Synthesis by Dr. Cécile Bour, May 12, 2019

About https://jamanetwork.com/journals/jama/fullarticle/2733521

Foreword

With the emergence of predictive software [1] the radiological criterion of breast density, i.e., the predominance of fibroglandular tissue over fatty tissue in the female breast, has become, despite the lack of conclusive studies, a risk factor for breast cancer on its own. Breast density is generally high in young, non-menopausal women (but may persist after menopause), in leaner women with low body fat, and in women undergoing hormone replacement therapy during menopause.

As we said, it is a radiological criterion; whether this characteristic is really associated with an increased risk of cancer, opinions diverge and the question is far from being decided in the course of studies, which does not prevent opinion leaders from raising the scarecrow of dense breasts to terrorize women, if need be....[2]

What is established, however, is that with high breast density the discriminating power of mammography and the ability of the radiologist's eye to detect a lesion are greatly diminished, and it is only a short step from there to make a shortcut between breast density and cancer risk.

Available studies

Several studies are available, starting with the Wolfe study [3] on the relationship between breast density and breast cancer risk. This old study was strongly contested at the time, even by the supporters of screening.

Other studies have since been published, studying the relevance of linking this density factor with other risk factors, in order to develop models for calculating the risk of contracting breast cancer within 5 years. [4] [5] [6] [7] [8] [9] [10]

Today, there is no convincing evidence that high breast density is associated with risk of death from breast cancer.
Today, no tool for estimating the risk of breast cancer using breast density has yet proven its relevance.

The HAS(Higher Authority for Health in France), in a work on the identification of risk factors, writes:

 "High pre-menopausal breast density was not retained as a risk factor at the end of the work of part 1."[11]

The viewpoint published in JAMA on May 9, 2019[12]

The background is the adoption by the US Congress of legislation on breast density.[13]

More precisely this legislation requires the US Food and Drug Administration (FDA)[14] as part of the regulatory process to ensure that all mammography reports and summaries provided to patients include information on women' s breast density. This authority, which oversees the regulation of mammography facilities and quality standards, has previously required the reporting of breast density in radiologists' reports.

Based on published studies (see our bibliography), and according to the authors of this viewpoint published in JAMA, breast density as a risk factor for developing breast cancer draws attention to the fact that the associated increase in cancer risk is modest, and that for women diagnosed with breast cancer, increased breast density was not associated with an increased risk of poor-prognosis cancer or death from breast cancer.

Dense breasts are common (43% of women aged 40 to 74 years) and the majority of women with dense breasts will not develop breast cancer....

According to the editors of this article, notification of breast density may increase confusion and anxiety related to mammography and breast cancer, without providing clear recommendations on what women with dense breasts should do.

The USPSTF [15], in 2016, concluded that there was insufficient evidence to recommend additional breast imaging in women with dense breasts. This group raises several points of concern with this legislation requiring notification of breast density information to women.

  • Significant variability and limited reproducibility in the determination of dense breasts. This variability exists on an examination whether it is read by one radiologist or by different radiologists. The exam for a given patient may have different classifications and lead to misunderstandings leading to a reduction in a woman's confidence in screening in general, and confusion about her own breast cancer risk.
  • Uncertainty about initiatives undertaken by women who have been notified of significant breast density to reduce their risk of dying from breast cancer. 
    This refers to the request for additional tests for which there is no evidence to support the indication, as there is no evidence that the addition of imaging other than mammography in women with dense breasts will reduce cancer mortality; instead, these additions increase false positives, unnecessary biopsies, and overdiagnosis. The recall rate is significantly increased by the addition of ultrasound (by 14%), and by the addition of MRI (from 9 to 23%) with low PPVs[16] and an obvious additional cost. The authors remind us that MRI, often considered to be harmless, is likely to have a (small) excess risk of nephrogenic systemic fibrosis, and uncertain risks of gadolinium deposition in the brain when the examinations are repeated. Tomosynthesis (TS) is mentioned as an additional technique used, but the authors point out that longer-term studies are needed to determine whether the routine use of TS in women with dense breasts leads to a real improvement in breast cancer outcomes (mortality, decrease in the rate of serious cancers).
  • Difficulty in communicating information about breast density to patients. 
    Experts consider this communication difficult and dependent on the literacy level of the population. Study results show poor understanding and confusion and misinformation of patients when information about breast density is given.

Impact Analysis of FDA[17]

In this analysis the FDA claims that mandating breast density reporting would reduce breast cancer mortality in women, as well as costs through early detection of cancers .... But the authors of the viewpoint point to a troubling lack of evidence to support this arbitrary conclusion.

The FDA analysis failed to include in its calculation the costs associated with overdiagnosis, with overtreatment due to additional tests, and the costs of additional visits to primary care physicians.

In conclusion

The authors believe that breast density notification has implications for public health and that physicians, researchers, public health experts, and organizations should take a stand against this imposed rule.

Breast density notification could give clinicians and patients the opportunity to discuss a particular woman's risk of breast cancer, which depends on many factors other than breast density.

Predictive models of breast cancer risk include breast density, but its addition improves predictive estimates little. The addition of complementary imaging should be limited to high-risk women based on other risk factors to be included than breast density alone.

Discussions about the potential benefit of additional imaging for dense breasts should focus on the lack of evidence for a reduction in breast cancer deaths, and the well-known increase in false positives, unnecessary biopsies, and increased health care costs, as well as increased overdiagnosis and overtreatment.

In particular, when deciding on annual surveillance for high-risk women, these elements should be taken into consideration.

Clinicians should also engage patients in discussions about the importance of lifestyle (limiting alcohol, avoiding obesity, regular exercise) to reduce breast cancer risk.

Research will be needed to improve the coherence of reports on breast density and the quality of communication.

Additional research will also be essential to judge the long-term outcomes of complementary imaging to determine whether the benefits outweigh the harms.

But the authors point out that such studies will be increasingly difficult to conduct if the use of complementary imaging is routinely incorporated into screening mammography in women with dense breasts, which is currently the case (Editor's note).

Bibliography

[1]  see for example the software

Mammorisk http://mypebs.cancer-rose.fr/le-logiciel-mammorisk/

[2] http://sante.lefigaro.fr/article/les-seins-denses-un-risque-accru-de-tumeur/  itw du Dr Cutuli à propos d'une étude du NEJM de 2007( https://www.nejm.org/doi/full/10.1056/NEJMoa062790 )

[3] Wolfe JN. Breast patterns as an index of risk for developing breast cancer. AJR 1976;126:1130-9.

Breast patterns as an index of risk for developing breast cancer

JN Wolfe - American Journal of Roentgenology, 1976 - Am Roentgen Ray Soc

[4]  2011 Annals of Internal Medicine Personalizing Mammography by Breast Density and Other Risk Factors for Breast Cancer: Analysis of Health Benefits and Cost-Effectiveness- John T. Schousboe, MD, PhD; Karla Kerlikowske, MD, MS; Andrew Loh, BA; and Steven R. Cummings, MD
https://annals.org/aim/article-abstract/747009/personalizing-mammography-breast-density-other-risk-factors-breast-cancer-analysis?doi=10.7326%2f0003-4819-155-1-201107050-00003

"Mammographic screening should be individualized based on a woman's age, breast density, history of breast biopsy, family history of breast cancer, and knowledge regarding the benefits and harms of screening." 

[5] https://www.researchgate.net/publication/273154592_The_Contributions_of_Breast_Density_and_Common_Genetic_Variation_to_Breast_Cancer_Risk

The Contributions of Breast Density and Common Genetic Variation to Breast Cancer Risk
Article (PDF Available) in JNCI Journal of the National Cancer Institute 107(5) · May 2015 with 77 Reads
DOI: 10.1093/jnci/dju397 · Source: PubMed
Celine M Vachon

[6] McCormack VA, dos Santos Silva I. Breast density and parenchymal patterns as markers of breast cancer risk: a meta-analysis. Cancer Epidemiol Biomarkers Prev. 2006;15(6):1159–1169
https://www.ncbi.nlm.nih.gov/pubmed/16775176

[7] KERlikowske K, Cook AJ, Buist DS, et al. Breast cancer risk by breast density, menopause, and postmenopausal hormone therapy use. J Clin Oncol. 2010;28(24):3830–3837.
https://www.ncbi.nlm.nih.gov/pubmed/20644098

[8] https://link.springer.com/article/10.1007/s10549-011-1853-z

Breast Cancer Research and Treatment
May 2012, Volume 133, Issue 1, pp 1–10| Cite as

Risk prediction models of breast cancer: a systematic review of model performances Thunyarat Anothaisintawee, Yot Teerawattananon, Chollathip Wiratkapun

"Most (risk prediction) models have produced relatively low discrimination in internal and external validations. This low discriminative accuracy of existing models may be due to a lack of knowledge of risk factors, heterogeneous subtypes of breast cancer, and different distributions of risk factors among populations." 

[9] McCarthy AM, WE Barlow, Conant EF, et al; Consortium PROSPR. Cancer du sein de mauvais pronostic diagnostiqué après mammographie de dépistage avec résultats négatifs.  JAMA Oncol . 2018; 4 (7): 998-1001. doi: 10.1001 / jamaoncol.2018.0352 

ArticlePubMedGoogle ScholarCrossref

"Breast density has received much attention as a primary factor identifying the need for additional screening, but it may be more effective to consider both breast density and age to identify women at risk for poor prognosis breast cancer."

[10] Gierach GL, Ichikawa L, Kerlikowske K, et al. Relation entre la densité mammographique et la mortalité par cancer du sein dans le Consortium de surveillance du cancer du sein.  J Natl Cancer Inst . 2012; 104 (16): 1218-1227. doi: 10.1093 / jnci / djs327

"High mammographic breast density was not associated with risk of death from breast cancer or any cause after controlling for other patient and tumor characteristics. Thus, risk factors for breast cancer development may not necessarily be the same as factors influencing risk of death after breast cancer development."

[11] https://www.has-sante.fr/portail/upload/docs/application/pdf/2014-05/depistage_du_cancer_du_sein_chez_les_femmes_a_haut_risque_volet_1_vf.pdf

Page 53

[12] https://jamanetwork.com/journals/jama/fullarticle/2733521

May 9, 2019

New federal requirements to educate patients about breast density will help patients?

Nancy L. Keating, MD, MPH 1,2; Lydia E. Pace, MD, MPH 2,3

Dr. Nancy L. Keating is Professor, Health Care Policy, Harvard Medical School, Associate Physician, Medicine, Brigham And Women's Hospital

[13] Hoeven J. An Appropriations Bill Relating to Agriculture, Rural Development, Food and Drug Administration Appropriations, 2019, S 115-259, 115th Congress, 2nd Session (2018). https://www.congress.gov/congressional-report/115th-congress/senate-report/259/1?q=%7B%22search%22%3A%5B%22farm%22%5D%7D

[14] The Food and Drug Administration is the U.S. Food and Drug Administration.

[15] Melnikow J, JJ Fenton, Whitlock EP, et al. Supplemental breast cancer screening for women with dense breasts: a systematic review for the US Preventive Services Task Force. 

Ann Intern Med . 2016; 164 (4): 268-278. doi: 10.7326 / M15-1789PubMed 

(USPSTF, United States Preventive Services Task Force is an independent U.S. preventive services task force of primary care and prevention experts that systematically reviews evidence of effectiveness and develops recommendations for clinical preventive services).

16] Positive predictive value, which is the likelihood that the subject actually has cancer when he or she has a positive test.

[17] Office of Policy, Planning, Legislation and Analysis, Office of the Commissioner, Food and Drug Administration. Mammography Quality Standards Act; Amendments to Part 900 Regulations: File No. FDA-2013-N-0134.

Mammography Quality Standards Act; Amendments to Part 900 Regulations (Proposed Rule) Regulatory Impact Analysis

https://www.fda.gov/about-fda/economic-impact-analyses-fda-regulations/mammography-quality-standards-act-amendments-part-900-regulations-proposed-rule-rule-regulatory-impact-


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