Department of Research & Evaluation News

A study of 316,443 patients shows that 7.4% of patients repeated fecal testing rather than proceeding directly to colonoscopy as guidelines recommend, and of those who repeated home tests, over half did not have a colonoscopy within one year.

Colorectal cancer is the second most common cancer-related cause of death in the United States, but screening with fecal blood tests (and more commonly now, the fecal immunochemical test [FIT]), is associated with reductions in colorectal cancer-related deaths. Fecal testing is typically more popular than having a colonoscopy as the initial step in colorectal cancer screening because it can be done at home and mailed to a laboratory. However, for those with a positive home test result, it is important to get a colonoscopy quickly. Longer time intervals between a positive fecal test and a colonoscopy, which allows a doctor to make a cancer diagnosis, are associated with poorer colorectal cancer outcomes.

“The good news is that the majority of patients in our study received a recommended colonoscopy after a positive result from a home test — this is the absolute best way we have to catch colorectal cancer early and get it treated,” said lead researcher Erin E. Hahn, PhD, of the Kaiser Permanente Southern California Department of Research & Evaluation and the Kaiser Permanente Bernard J. Tyson School of Medicine, both in Pasadena, Calif.  “What is worrisome is that we did see that some patients repeated the home tests instead of immediately getting a colonoscopy. We want to make sure that everyone gets the right kind of screening and follow-up care to catch these cancers.”

The study was published in the Journal of General Internal Medicine on May 21, 2024.

To learn about the repeat testers, researchers examined data from hundreds of thousands of medical records and interviewed dozens of patients between the ages of 50 and 89 who had positive fecal tests between 2010 and 2018 at 4 different health systems: Kaiser Permanente Southern California, Kaiser Permanente Northern California, Kaiser Permanente Washington, and Parkland Health in Texas. Researchers also interviewed physicians.

The study showed that among repeat testers, only 41% went on to receive a colonoscopy within one year of their initial positive fecal test. Additionally, the researchers found that among those with repeat tests, those with an initial positive test followed by a negative second test were significantly less likely to receive a colonoscopy than those with 2 positive tests, even though it is recommended that anyone who gets a positive test has a colonoscopy.

“We found that of the patients who repeated the home tests, the pattern of results made a difference in what happened next. If a patient had 2 positive results, they were more likely to get the recommended colonoscopy compared to patients who had a positive followed by a negative result,” Dr. Hahn said. “This makes an intuitive kind of sense — the 2 positives might reinforce the importance of getting the colonoscopy. However, even for patients who have a positive followed by a negative result, they still need a colonoscopy. The home tests indicate if there is blood in the stool, and colorectal cancers do not always bleed all the time. That’s why it is so important to get appropriate follow-up care after an initial positive result from a home test.”

People who were ages 65 to 89 with higher levels of chronic conditions were significantly more likely to do a repeat fecal test rather than go for a colonoscopy.

To learn more, researchers interviewed patients who had tested twice rather than go in for their colonoscopy after the first positive test.

Patients who repeated the test rather than a have a colonoscopy said they did it to avoid or delay the colonoscopy or to rule out other health conditions that might have caused the positive result. Some patients said they felt a second test would provide reassurance about the results.

Researchers also interviewed those patients’ doctors. Most clinicians initially stated they believed it was unlikely physicians would order a repeat fecal test, with a few later acknowledging some clinicians would likely give in if patients pushed for it or negotiated with the physician.

Dr. Hahn said that she would tell physicians, “if a patient is hesitant about getting a colonoscopy after a positive FIT, it’s critical to talk to them about what the FIT results really mean: There is blood in the stool that might indicate colorectal cancer, and even if the patient has a negative result next week, the cancer could still be there. It’s so important to find these cancers early so we can treat them effectively.”

This study was supported by the National Cancer Institute’s Population-based Research to Optimize the Screening Process II (PROSPR II) consortium.

In addition to Dr. Hahn, authors on the paper included Corrine E. Munoz-Plaza, MPH; Nirupa R. Ghai, PhD; Katherine Pak, MS; Britta I. Amundsen, MA; Richard Contreras, MS; and Nancy Cannizzaro, PhD; of the Department of Research & Evaluation; Christopher D. Jensen, PhD, and (senior author) Theodore R. Levin, MD, of Kaiser Permanente Division of Research, Oakland, Calif.; Jessica Chubak, PhD, and Beverly B. Green, MD, of Kaiser Permanente Washington Health Research; Celette Sugg Skinner, PhD, University of Texas Southwestern Medical Center, Dallas; Ethan A. Halm MD, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ; and Joanne E. Schottinger, MD,  Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, Calif.