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?

About 65 million women in the United States get a mammogram each year to look for signs of breast cancer. In about 60,000 of these women, a mammogram shows abnormal cells inside the milk ducts in the breast. This condition is called ductal carcinoma in situ (DCIS). Only 20–30 percent of DCIS cases turn into invasive cancer, which is cancer that spreads and causes illness. Many women can live with DCIS without it ever harming them. When deciding whether DCIS might become invasive, doctors consider if a patient has other risk factors, such as a history of breast cancer. Doctors may also consider whether the DCIS is low- to intermediate-grade. Low- to intermediate-grade cancer cells look more like normal cells and often spread very slowly.

Doctors usually treat low-risk DCIS the same way they treat invasive cancers, using surgery and radiation. But for many women, surgery and radiation cause pain and worry. These harms could be avoided if low-risk DCIS never turned into invasive cancer.

Many doctors and researchers believe that, instead of having surgery or radiation right away, women with low-risk DCIS can safely choose to watch for changes in their condition through regular checkups. This is called watchful waiting. This study looks at whether it’s safe for women who have low-risk DCIS to watch and wait instead of having standard treatment.

Who can this research help?

Results from this study can help women who have low-risk DCIS and their doctors decide whether to start treatment or watch and wait, treating it only if it develops into invasive cancer.

What is the research team doing?

The research team is working with 100 clinics around the United States. The researchers are recruiting 900 women ages 40 and older who are newly diagnosed with low-risk DCIS. The research team is assigning patients to one of two groups by chance: standard treatment or watchful waiting.

Patients in the standard treatment group can choose between recommended treatments. These include radiation and surgery. In the watchful waiting group, doctors check patients regularly to make sure that DCIS hasn’t turned into invasive cancer. If it has, the patient can choose to have surgery or radiation.

Patients in both groups can also decide to have endocrine therapy. This is a type of hormone treatment. In some women, it helps keep low-risk DCIS from spreading.

The researchers are looking at the rate of new invasive cancers in both groups for two years after diagnosis. The research team is also surveying patients every year for five years after they start the study to learn about their quality of life and whether they feel anxious or depressed. The study includes a patient-leadership team that has partnered with researchers in all phases of study planning and development.

Research methods at a glance

Design Element Description
Study Design Randomized controlled trial
Population Women ages 40 and older who are newly diagnosed with low-risk ductal carcinoma in situ (DCIS), with no prior history of breast cancer
  • Active surveillance (monitoring), with or without endocrine therapy
  • Standard treatment (surgery or radiation), with or without endocrine therapy

Primary: rate of new invasive cancer after diagnosis of DCIS

Secondary: quality of life (anxiety, depression, coping, feelings of uncertainty), disease progression (rates of surgical procedures, ipsilateral or contralateral invasive cancer, overall survival, and breast-cancer-specific survival), rates of follow-up interventions, and patient-reported outcomes including adherence to hormonal therapy, symptoms of breast cancer, general and breast-specific pain, body image, decisional regret, DCIS knowledge and risk perception, communication with physicians, financial burden, employment status, concerns about future breast events, and co-morbidity

Timeframe 2-year follow-up for primary outcome

Project Information

Shelley Hwang, MD, MPH
Alliance for Clinical Trials in Oncology Foundation
Comparison of Operative versus Medical Endocrine Therapy for Low Risk DCIS: The COMET Trial

Key Dates

January 2016
October 2024

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: April 12, 2024