Results Summary

What was the research about?

Ductal carcinoma in situ, or DCIS, makes up about 25 percent of new breast cancer diagnoses. In DCIS, the cancer cells occur inside milk ducts. DCIS may or may not turn into invasive cancer, which spreads and causes illness.

Women with DCIS often have breast-conserving surgery to treat DCIS. This surgery removes the abnormal cells and some of the tissue around them. Sometimes the surgeon also removes some lymph nodes around the tumor, called sentinel lymph nodes, to test if the cancer has spread. This sentinel lymph node biopsy may cause side effects like pain or infection.

In this study, the research team compared older women with DCIS who’d had surgery with and without sentinel lymph node biopsy. They wanted to learn if the biopsy

  • Increased side effects
  • Reduced the spread of cancer
  • Helped patients live longer

The research team looked at four types of side effects in the short term and in the longer term. The side effects included swelling, infections, pain, and fluid under patients’ skin where they’d had surgery.

What were the results?

Short-term side effects. Women who had sentinel lymph node biopsy were more likely to have one or more of the four types of side effects within nine months of DCIS diagnosis compared with women who didn’t have a biopsy.

Long-term side effects. Compared with women who didn’t have a biopsy, those who had sentinel lymph node biopsy were also more likely to have swelling up to 12 years after DCIS diagnosis. The two groups didn’t differ in how likely they were to have infections, pain, and fluid under the skin.

Health effects. The study didn’t show differences between the two groups of women in how often the cancer spread or how long they lived after DCIS diagnosis.

Who was in the study?

The research team used data from a national Medicare database that included 7,127 women with DCIS who were between the ages of 67 and 94 and who had breast-conserving surgery. Of these women, 88 percent were white, 8 percent were black, and 5 percent were other races; also, 5 percent were Hispanic. The average age was 75.

What did the research team do?

The research team compared the Medicare data for women diagnosed with DCIS who did and didn’t have sentinel lymph node biopsy. They looked at side effects that happened within 9 months after diagnosis, and at side effects, cancer spread, and length of life up to 12 years after diagnosis. The team took into account other things that might affect how likely patients were to have side effects, such as their age, year of diagnosis, and tumor size.

An advisory group of breast cancer survivors and doctors who treat cancer helped design the study.

What were the limits of the study?

Most women in the study were white and older than 66. Results may differ if the research team included women from different backgrounds. The women who had biopsies may have been different from the women who didn’t have them. The data didn’t include some information about patients, like other health problems, which could have affected the results.

Future research could include women who are younger and from more diverse backgrounds. Research could also include information about other health problems that might affect the results.

How can people use the results?

Older women and doctors can consider the results when making treatment decisions for DCIS.

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. The comments and responses included the following:

  • Reviewers questioned the choice of outcomes, including disease-specific survival and using mastectomy as a proxy for recurrence. The researchers explained that they focused on these patient-centered outcomes, along with local recurrence, based on discussions with patient and clinician stakeholders. The researchers used disease-specific survival to measure the impact of sentinel lymph node biopsy (SLNB) among patients with ductal carcinoma in situ (DCIS) to minimize selection bias because patients who had a SLNB procedure were likely to be healthier. The researchers also explained that they used mastectomy occurring nine months or more after DCIS diagnosis as a proxy for recurrence, which made it less likely that the mastectomy had been performed for clinical issues related to the initial diagnosis.
  • Reviewers asked why the researchers chose the age range of 67 to 94. The researchers responded that the age range was consistent with other analyses using the Surveillance, Epidemiology, and End Results (SEER) Medicare Database. Subjects were at least age 67, so data were available for two years in advance to assess comorbidity, since patients enroll in Medicare at age 65 typically. Patients were not older than 94 because of the short life expectancy and the small numbers of people in that age range.
  • Reviewers asked why the researchers used different cohorts for the study’s two aims. The researchers said the different cohorts reflected the SEER-Medicare data available to researchers at the time they conducted each portion of the study. For Aim 1, the most recent available data came from 2014. For Aim 2, they were able to use 2016 data.

Conflict of Interest Disclosures

Project Information

Shiyi Wang, MD, PhD
Yale University
Comparative Effectiveness of Sentinel Lymph Node Biopsy for Ductal Carcinoma In Situ

Key Dates

April 2016
June 2019

Study Registration Information


Has Results
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
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Last updated: February 15, 2024