Results Summary

What was the research about?

About 1 million women in the United States have been diagnosed with a condition called ductal carcinoma in situ, or DCIS. In DCIS, abnormal cells are found inside milk ducts in the breast. DCIS may or may not turn into cancer. Having DCIS increases a woman’s risk of getting a second diagnosis of DCIS or cancer in either breast.

One way doctors treat DCIS is to remove the abnormal cells and some of the tissue around them. This surgery is called a lumpectomy. Sometimes a patient and her doctor decide to have a mastectomy to remove the entire breast. To kill any abnormal cells that surgery may have missed, doctors may also add radiation. Choosing what kind of surgery to have is personal. Patients must decide if keeping their breast is worth the higher risk of getting DCIS again or cancer. Having information about the risks and benefits of each treatment could help patients and doctors choose a treatment.

In this study, the research team looked at records from national databases to learn

  • What patient traits, such as age or race, may affect a woman’s risk of getting another DCIS or breast tumor in the other breast
  • How likely it is that a woman who had treatment for DCIS will have a mastectomy if she has a second breast cancer

Next, the research team updated a computer model to predict the chances of survival, getting another DCIS, or getting breast cancer in the other breast. They compared the predicted outcomes from the model with data from other sources to see if the outcomes were like real patient experiences. The team used the model to create an online resource for women diagnosed with DCIS. This website allows women to see what’s likely to happen after different treatments.

What were the results?

Patient traits. Traits linked to getting another DCIS or cancer in the other breast included

  • Age
  • Year of DCIS diagnosis
  • Race
  • Tumor size
  • Type of estrogen receptors, which are proteins on cells that tell them to grow

Women treated in parts of the country where doctors often use radiation to treat DCIS were more likely to have a mastectomy for a second DCIS, even if they had not been treated with radiation for the first one.

Predicting future outcomes. The computer model could accurately predict the chance that a woman would get DCIS or breast cancer within 10 years. The model successfully estimated how long women ages 45 and 60 would live after their first DCIS diagnosis. But the model overestimated how long women aged 70 years would live.

What did the research team do?

To build the computer model, the research team used data from other studies and databases. Next, the team used different data to check the computer model’s results. They then developed the website.

What were the limits of the study?

Some information may be missing from the databases. For example, the databases may not list all the patients who got a second breast tumor. Also, the databases didn’t have information about patient preferences for different treatments. The results might be different if the databases had this missing information.

Future research could look at how a patient’s actual choice for the first DCIS treatment may affect future outcomes.

How can people use the results?

The model can help predict future outcomes based on the initial treatment choice for DCIS. Doctors and patients could use the information from the model to help choose a DCIS treatment.

Final Research Report

View this project's final research report.

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 reviewers commented, and the researchers made changes or provided responses. Those comments and responses included the following:

  • The reviewers questioned the adequacy of the multivariable models of the choice of breast cancer treatments, breast conserving surgery versus radiation therapy. The researchers acknowledged that there were some unmeasured factors, such as previous hormone use and availability of radiation oncology services, that could influence women’s decision making. They noted in their limitations that the study did not include these factors as potential confounders.
  • The reviewers expressed concern about the low rate of reporting of estrogen receptor (ER) status, 14 percent, in the data set, given the results showing the association of ER status with the occurrence of contralateral breast cancer. The reviewers noted the possibility that this association was invalid given the amount of missing data for ER status. They also noted the possibility of this association being invalid given the potential for a difference in the women for whom ER status was known and the women whose ER status was unknown. The researchers acknowledged that the lack of additional information on ER status limited the conclusions that could be made from these results. However, they also noted that although testing for ER status varied systematically based on the sophistication of specific clinics or regions, there was no reason to believe that the consequent systematic selection of patients for ER testing would bias the clinical characteristics of ER positive versus ER negative cases.

Conflict of Interest Disclosures

Project Information

Rinaa Punglia, MD, MPH
Dana-Farber Cancer Institute
Impact of Radiation Therapy on Breast Conservation in DCIS

Key Dates

May 2013
September 2018

Study Registration Information


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Last updated: January 25, 2023