Project Summary

PCORI has identified the need for large studies that look at real-life questions faced by diverse patients, caregivers, and clinicians. To address this need, PCORI launched the Pragmatic Clinical Studies initiative in 2014. Pragmatic clinical studies allow for larger-scale studies with longer timelines to compare the benefits and harms of two or more approaches known to be effective for preventing, diagnosing, treating, or managing a disease or symptom. They focus on everyday care for a wide range of patients. This research project is one of the studies PCORI awarded as part of this program.

This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final.

What is the research about?

In the United States, 27.6 million women ages 40-74 have dense breasts. Dense breasts have less fatty tissue and more nonfatty tissue than nondense breasts. Women who have dense breasts have an increased risk for breast cancer. These women also have an increased risk that a mammogram will miss cancer.

Doctors use three imaging tests to look for breast cancer: mammograms, tomosynthesis, and magnetic resonance imaging (MRI). Often, doctors use MRI and/or tomosynthesis, a type of 3D x-ray, in addition to mammograms for breast cancer screening or diagnosis. For example, a doctor may order an MRI after a mammogram to see where the cancer is located in the breast before doing surgery.

In this study, the research team wants to know whether women with dense or nondense breasts should get tomosynthesis or MRI in addition to mammograms when getting screened for breast cancer. The team also wants to know if having an MRI after a new cancer diagnosis and before surgery benefits women with dense or nondense breasts.

Who can this research help?

Findings from this study may help women and their doctors weigh the benefits and harms of breast cancer screening with or without follow-up tests and decide which approach to use. The findings may also help policy makers write breast cancer screening guidelines.

What is the research team doing?

The research team is collecting information from six breast imaging registries from 2005 to 2017. These registries collect information such as whether or not women have dense breasts or have been diagnosed with breast cancer. Women join the study after they get a breast imaging test at a clinic that is part of one of the registries.

The study has two parts. In the first part, the research team is comparing three screening approaches for women with dense or nondense breasts:

  • mammography alone
  • mammography plus tomosynthesis
  • mammography plus MRI

The team is looking at how often breast imaging tests correctly find cancer. The team is also looking at screening harms, such as how often women have a breast biopsy when they do not have breast cancer.

In the second part of the study, the research team is comparing mammography alone versus mammography plus MRI for women with dense or nondense breasts who will have breast cancer surgery. The team wants to know if a breast MRI before surgery helps doctors find and remove all the cancer, or if the MRI leads to more biopsies and treatment without the benefit of the cancer being less likely to come back.

Cancer advocacy groups, insurers, doctors, and patients are helping to design the study and identify which questions are most important to patients.

Research methods at a glance

Design Element Description
Design Observational: cohort study
Population Women ages 40-79 without a history of breast cancer undergoing screening mammography; women ages 18 and older diagnosed with breast cancer undergoing preoperative work-up
  • Breast cancer screening with mammography alone versus mammography plus tomosynthesis or mammography plus MRI for women with dense or nondense breasts
  • Breast cancer screening with mammography alone versus mammography plus MRI for women with dense or nondense breasts who will have surgery for first breast cancer diagnosis

Primary: rates of accurate early stage invasive cancer detection, missed invasive cancer, advanced stage invasive cancer detection, false positive screening tests, screens resulting in a biopsy recommendation with no cancer diagnosis, and additional breast cancers detected, patient-reported outcomes including cancer worry and knowledge and attitudes toward breast cancer screening and treatment decisions

Secondary: sensitivity, specificity, positive predictive value, rate of unilateral mastectomy, or bilateral mastectomy, lumpectomy with reconstruction, or lumpectomy without reconstruction, negative predictive value of work-up with MRI, negative predictive value of work-up without MRI, core biopsy rates, surgical biopsy rate, benign biopsy rate

Timeframe Timeframe Length of follow-up for collecting data on primary outcomes. View Glossary Up to 3-year follow-up for primary outcomes from time of screening or diagnosis 

Journal Citations

Related Journal Citations

Project Information

Diana Miglioretti, PhD
University of California, Davis
Comparative Effectiveness of Breast Cancer Screening and Diagnostic Evaluation by Extent of Breast Density

Key Dates

May 2016
March 2023

Study Registration Information


Award Type
Health Conditions Health Conditions These are the broad terms we use to categorize our funded research studies; specific diseases or conditions are included within the appropriate larger category. Note: not all of our funded projects focus on a single disease or condition; some touch on multiple diseases or conditions, research methods, or broader health system interventions. Such projects won’t be listed by a primary disease/condition and so won’t appear if you use this filter tool to find them. View Glossary
Populations Populations PCORI is interested in research that seeks to better understand how different clinical and health system options work for different people. These populations are frequently studied in our portfolio or identified as being of interest by our stakeholders. View Glossary
Intervention Strategy Intervention Strategies PCORI funds comparative clinical effectiveness research (CER) studies that compare two or more options or approaches to health care, or that compare different ways of delivering or receiving care. View Glossary
State State The state where the project originates, or where the primary institution or organization is located. View Glossary
Last updated: January 20, 2023