Project Summary

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?

Colon polyps are small bunches of cells that can form in the colon. Most polyps are harmless, but some can grow bigger and turn into colorectal cancer, or CRC. Screening can help find CRC early, when it is easier to treat. To screen for colorectal cancer, doctors commonly recommend one of the two following tests:

  • Colonoscopy, in which doctors insert a long, flexible tube into the rectum and colon. A camera at the end of the tube lets doctors see changes in the colon that may indicate cancer. Colonoscopy is the main way of screening for CRC in the United States. But for older patients, the possible harms from colonoscopy, such as bleeding or a tear in the colon, may outweigh the benefits.
  • At-home stool tests detect blood in the stool, which can be an early sign of CRC. For this test, people collect a sample of their stool at home and mail it to a lab. Doctors often recommend a stool test for adult patients between the ages of 50 and 75.

In this study, the research team is comparing colonoscopy and at-home stool tests in older patients with a history of small colon polyps. The team is looking to see how well each screening test detects CRC and to learn about patients’ experiences with both tests.

Who can this research help?

Results may help doctors when deciding how to screen for CRC in older patients.

What is the research team doing?

The research team is recruiting 8,946 adults between the ages of 70 and 82 who have a history of small colon polyps. The team is assigning patients by chance to one of two groups. In the first group, patients complete an annual stool test. If the stool test is positive, the doctor recommends a colonoscopy. In the second group, patients receive a colonoscopy. Patients in both groups receive additional colonoscopies after the first one as needed.

The research team is surveying patients yearly for 6 years and looking at medical records for up to 11 years to see if patients have had any changes in polyps or a new cancer diagnosis. Surveys also ask about patients’ experiences with each screening test and if patients have worries about cancer. The team is comparing the number of new diagnoses across groups to see how well each screening test detects CRC.

Patients who have had colon polyps or CRC, clinicians, health systems, support groups, and health insurers are helping to plan and conduct this study.

Research methods at a glance

Design ElementDescription
DesignRandomized controlled trial
Population8,946 English- or Spanish-speaking adults ages 70–82 with a history of low-risk colon polyps
  • Stool testing
  • Colonoscopy

Primary: incidence of advanced neoplasia (i.e., new or abnormal growth of tissue, including CRC and advanced polyps)

Secondary: major and minor harms within 30 days of colonoscopy and patient-reported satisfaction with and trust in screening test, cancer worry, perceived cancer susceptibility, psychological benefits of surveillance, and overall health

Timeframe  Timeframe Length of follow-up for collecting data on primary outcomes. View Glossary 11-year follow-up for primary outcome

Project Information

Audrey Calderwood, MD, MS
Theodore Levin, MD
Dartmouth-Hitchcock Clinic
Colonoscopy vs. Stool-Based Testing for Older Adults With a History of Colon Polyps

Key Dates

September 2021
February 2029

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: March 29, 2024