Authors' objectives: Screening for breast cancer is the process of looking for the disease before any symptoms appear, so that it can be caught and treated early. Many factors affect a person’s risk for breast cancer, including age, a strong family history of the disease, and breast density. Variations in breast density are normal and common, but higher breast density increases the risk of cancer and makes it harder to see cancers on a mammogram (a 2-dimensional breast x-ray). One way to improve cancer detection for people with dense breasts might be to use other types of imaging in addition to mammography (called supplemental screening). Types of breast imaging that could be added include contrast-enhanced mammography, ultrasound, digital breast tomosynthesis (3-dimensional breast x-ray), or magnetic resonance imaging (MRI). This health technology assessment looked at how accurate, safe, effective, and cost-effective supplemental screening is for people with dense breasts. It also looked at the budget impact of publicly funding supplemental screening; the experiences, preferences, understandings, and values of people with dense breasts and their health care providers; and ethical issues related to supplemental screening for people with dense breasts.

Authors' results and conclusions: Supplemental screening with ultrasound, DBT, or MRI as an adjunct to mammography detected more cancers and increased the number of recalls and biopsies, including false-positive results. Fewer interval cancers tended to occur after supplemental screening compared to mammography alone. It is unclear whether supplemental screening as an adjunct to mammography would reduce breast cancer–related or overall mortality among people with dense breasts. Supplemental screening with ultrasound, DBT, or MRI as an adjunct to mammography in people aged 50 to 74 years improved cancer detection but increased costs. Depending on the type of imaging modality, publicly funding supplemental screening in Ontario over the next 5 years would require additional total costs between $15 million and $41 million for people with dense breasts, and between $4 million and $10 million for people with extremely dense breasts. The people we engaged with directly valued the potential clinical benefits of supplemental screening and emphasized that patient education and equitable access should be a requirement for implementation in Ontario. Our review of the qualitative literature found that the concept of breast density is poorly understood, both by people with dense breasts and by some general practitioners. People with dense breasts who receive routine mammography (especially those who receive health care in their nonpreferred language or are perceived to have lower economic status or health literacy) and their general practitioners may not have the awareness or knowledge to make informed decisions about supplemental screening. Some people with dense breasts experienced emotional distress from barriers to accessing supplemental screening, and many wanted to engage in supplemental screening, even when educated about its potential harms, including false-positives and overdiagnosis. Given an overall lack of robust evidence about morbidity and mortality associated with supplemental screening for people with dense breasts, it is not possible to determine whether funding supplemental screening for dense breasts delivers on the ethical duties to maximize benefits and minimize harms for populations and individuals. It is likely that existing inequities in access to breast screening and cancer treatment will persist, even if supplemental screening for dense breasts is funded. Continued efforts to address these inequities by removing barriers to screening might mitigate this concern. It will be important to identify and minimize sources of uncertainty related to benefits and risks of supplemental screening for dense breasts to optimize the capacity for everyone involved to live up to their ethical obligations. Some of these may be resolved with further evidence related to the outcomes of supplemental screening for dense breasts.

Authors' recommendations: Ontario Health, based on guidance from the Ontario Health Technology Advisory Committee, recommends publicly funding supplemental screening as an adjunct to mammography for people with extremely dense breasts.

Authors' methods: We performed a systematic literature search of the clinical evidence published from January 2015 to October 2021. We assessed the risk of bias of each included study using the Cochrane Risk of Bias or RoBANS tools, and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature review and conducted cost-effectiveness analyses with a lifetime horizon from a public payer perspective. We also analyzed the budget impact of publicly funding supplemental screening as an adjunct to mammography for people with dense breasts in Ontario. To contextualize the potential value of supplemental screening for dense breasts, we spoke with people with dense breasts who had undergone supplemental screening; performed a rapid review of the qualitative literature; and conducted an ethical analysis of supplemental screening as an adjunct to mammography.

Project Status: Completed

URL for project: https://www.hqontario.ca/evidence-to-improve-care/health-technology-assessment/reviews-and-recommendations/supplemental-screening-as-an-adjunct-to-mammography-for-breast-cancer-screening-in-people-with-dense-breasts

URL for protocol: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=311789

Year Published: 2023

URL for published report: https://www.hqontario.ca/evidence-to-improve-care/health-technology-assessment/reviews-and-recommendations/supplemental-screening-as-an-adjunct-to-mammography-for-breast-cancer-screening-in-people-with-dense-breasts

Requestor: OHTAC/Ontario Ministry of Health

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: Canada

Province: Ontario

Organisation Name: Ontario Health

Contact Address: 525 University Ave, Toronto, ON M5G 2L3

Contact Name: Nancy Sikich, Director Health Technology Assessment

Contact Email: oh-hqo_hta@ontariohealth.ca

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