Results Summary

What was the research about?

More than 3 million women in the United States have had breast cancer. After their treatment is complete, these women usually receive yearly mammograms, an x-ray of the breast, to check for second breast cancers. When the first cancer comes back or a new breast cancer develops, it is a second breast cancer.

Sometimes doctors recommend that women get a breast MRI along with their mammogram. An MRI uses magnetic fields, or radio waves, and a computer to take pictures of the inside of the breast. But doctors don’t know whether adding a breast MRI is better than mammograms alone at finding second breast cancers.

In this study, the research team looked at how often mammograms and breast MRIs found second breast cancers. To do this, the team looked at health records of breast cancer survivors from a cancer registry. The registry combines data from sites across the country and includes information about women with previous breast cancers who had mammograms and breast MRIs.

What were the results?

When doctors used a breast MRI with or without a mammogram, they were more likely to find cancer than when they used a mammogram alone. Breast MRIs also led to more biopsies. Biopsies confirm whether a tissue sample is cancer or not. But they may cause scarring, pain, or infection. Women may worry that the cancer has come back, even if it hasn’t.

Who was in the study?

The study looked at health information for 13,266 women with a personal history of breast cancer. All had mammograms and/or breast MRIs to check for second breast cancers. Of these women, 77 percent were white, 9 percent were black, 9 percent were Asian or Pacific Islander, 3 percent were Hispanic, and 2 percent were mixed or other races. The registry included information from women with breast imaging tests done in California, New Hampshire, North Carolina, Vermont, and Washington State.

What did the research team do?

To identify which women had second breast cancers and how doctors found the cancer, the research team looked at

  • Details about patients’ first breast cancers
  • Imaging test results from mammograms and breast MRIs

A group of women with a personal history of breast cancer and cancer specialists helped guide the study.

What were the limits of the study?

The study included information for most patients, but information for some patients was missing. The results may have been different if the study included information for all patients. Having a second breast cancer is rare. As a result, the study didn’t include enough women to allow the team to look at results for specific groups of women.

Future research could see whether having breast MRIs with mammograms helps to find breast cancer for specific groups of women, such as by age at diagnosis or by how aggressive the first cancer was.

How can people use the results?

Patients and their doctors can use these results to help decide whether to use a breast MRI with the yearly mammogram to check for second breast cancers.

Final Research Report

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Peer-Review Summary

Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.

The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments. 

Peer review identified the following strengths and limitations in the report:

  • The reviewers stated that the report incorrectly described confounding. In the draft report, the researchers said confounding based on patient characteristics was a major limitation in previous breast cancer surveillance studies. The reviewers believed this statement to be incorrect because confounding is usually considered problematic in comparison studies, not in descriptive studies. The researchers countered that patient characteristics were still important factors in descriptive studies because they could influence imaging test results. Therefore, the researchers explained, confounding is relevant for earlier imaging studies.
  • The reviewers expressed concern that the report’s results did not justify its conclusions. The concern stemmed from inconsistent performance outcomes about which surveillance strategy was superior. Also, reviewers noted that some outcomes had insufficient power to identify minimal, but clinically significant, differences. The researchers noted that although some outcomes were underpowered, the basis for the conclusions was a holistic assessment. This assessment looked across performance outcomes because no single measure could best assess the performance of the diagnostic tools.
  • The reviewers asked for more information on missing data and patient attrition for the comparison study. The researchers added more information to the methods section about their plans to input missing data. The researchers also acknowledged that missing data could be a study limitation because they were unable to assess some potentially important confounders due to missing follow-up information.
  • The reviewers requested additional details on the results of the third aim, including a new table displaying all of the statistical information about the results. The researchers responded that this aim was a pilot study for the development of the decision aid. To reduce confusion, the researchers included the methods for developing the decision aid but no results.

Conflict of Interest Disclosures

Project Information

Karen Joanne Wernli, PhD, MS
Kaiser Permanente Washington Health Research Institute^
Comparative Effectiveness of Surveillance Imaging Modalities in Breast Cancer Survivors

Key Dates

September 2013
June 2018

Study Registration Information

^Kaiser Permanente acquired Group Health Cooperative in February 2017.


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Last updated: January 20, 2023