Results Summary

What was the research about?

Doctors use imaging tests, alone or together, to detect breast cancer, including:

  • Digital mammogram, or DM, a 2D x-ray
  • Tomosynthesis, or DBT, a 3D x-ray
  • Magnetic resonance imaging, or MRI, which uses magnetic fields and radio waves to take pictures

These tests may differ in their benefits, like detecting cancer early; their harms, like false alarms; and their failures, like missing a cancer diagnosis.

In this project, the research team did two studies to compare imaging tests:

  • Study 1 compared DM versus DBT for breast cancer screening. It also compared DM or DBT alone versus DM or DBT plus MRI.
  • Study 2 compared having or not having an MRI before surgery for women with breast cancer.

For both studies, the research team looked at women with dense and non-dense breasts separately. Having dense breasts is common but makes it hard to see cancer on DM and DBT and increases breast cancer risk.

What were the results?

Women with dense breasts.

Study 1. DBT and DM didn’t differ in study outcomes, except women who had DM had lower worry about cancer.

Compared with DM or DBT alone, women who also had an MRI had:

  • Higher benefits
  • Higher harms
  • No difference in failures
  • More confidence in screening
  • More worry about cancer

Study 2. Compared to women with breast cancer who didn’t have an MRI before surgery, women who had one had:

  • Higher rates of additional breast cancer detected at six months but not at three years
  • More worry about cancer
  • No difference in decision quality, conflict, or regret

Women with non-dense breasts.

Study 1. Compared with DM, screening with DBT had:

  • Higher benefits
  • Lower harms
  • No difference in failures or in women’s confidence in screening or worry about cancer

Compared with DM or DBT alone, women who also had an MRI had:

  • Higher benefits
  • Higher harms
  • No difference in failures
  • More confidence in screening
  • More worry about cancer

Study 2. Compared to women with breast cancer who didn’t have an MRI before surgery, those who had one had:

  • Higher rates of additional breast cancer detected at six months but not at three years
  • Improved decision quality
  • No difference in decision conflict and regret or worry about cancer

What did the research team do?

The research team used data from seven breast imaging registries across the United States. Study 1 included data from 504,150 women who had 1,377,902 screening tests. Study 2 included data from 20,383 women with breast cancer.

Subsets of 2,329 women from study 1 and 957 women from study 2 completed surveys on screening confidence, cancer worry, and decision quality.

Women who had breast cancer, doctors, and advocates gave input during the studies.

What were the limits of the study?

The research team didn’t assign women by chance to the imaging tests. Differences among women, such as reasons for screening, could have affected study outcomes.

Future research could look at other outcomes of imaging tests among women with dense and non-dense breasts.

How can people use the results?

Doctors and women can use the results when considering imaging tests for breast cancer.

Final Research Report

This project's final research report is expected to be available by April 2024.

Journal Citations

Related Journal Citations

Peer-Review Summary

The Peer-Review Summary for this project will be posted here soon.

Conflict of Interest Disclosures

Project Information

Diana L. Miglioretti, PhD
University of California, Davis
$8,128,405
Comparative Effectiveness of Breast Cancer Screening and Diagnostic Evaluation by Extent of Breast Density

Key Dates

May 2016
March 2023
2016
2023

Study Registration Information

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Last updated: September 7, 2023