New colorectal cancer screening guidelines emphasize advanced stool tests

With colorectal cancer a growing concern among younger people, the American Cancer Society has endorsed two new types of stool tests to encourage people to get screened while also recommending a limited role for new blood tests many patients find appealing.

The recommendations are an update to the ACS's screening guidelines – an update led by Andrew Wolf, MD, a cancer-prevention expert at UVA Health. He and a blue-ribbon panel of cancer experts conducted a systemic review of the available colorectal cancer tests to determine which are most effective. In addition to recommending a next-generation DNA stool test and a new type of RNA stool test, the group is advising doctors to recommend blood tests only to patients who decline all other options.

The recommendations come with a dose of pragmatism: "The most effective screening test," the panel concludes, "is the one that the patient completes."

The new guidance adds a stool RNA test and an updated stool DNA test to the menu of preferred options for colorectal cancer screening, which currently include colonoscopy and stool tests that detect tiny amounts of blood, among other options. Although the idea of a blood test for colorectal cancer sounds very attractive, they aren't yet as good as the other tests at detecting precancerous growths and early-stage cancer, so we don't believe they are as effective as a screening test. That said, we're very hopeful that broadening the array of options will get more folks screened and reduce the burden of suffering from colorectal cancer."

Andrew Wolf, MD, a professor emeritus, University of Virginia School of Medicine

About colorectal cancer

Colorectal cancer is the second-leading cause of cancer deaths in the United States, killing 55,000 people in 2026. Improvements in detection, screening and treatment have contributed to declining colorectal cancer death rates over the last several decades, but that decline has been accompanied since 2013 by an alarming increase in the cancer among people under the age of 50. Among that age group, colorectal cancer is now the leading cause of cancer death for men and the second-leading cause for women.

In response, the American Cancer Society in 2018 lowered the recommended age for initial colorectal cancer screening from 50 to 45 for people at average risk. It also affirmed the importance of screening tools such as stool-based tests as well as visual exams such as colonoscopies. Since then, however, new, multi-target stool tests and blood-based screening tests have become available. The new blood tests proved popular in a patient survey, with 53% of respondents saying they would prefer blood testing every three years to taking a stool test every year or receiving a colonoscopy every 10.

For the latest guideline update, Wolf and his colleagues examined the effectiveness of the new tests to provide doctors with guidance on if, how and when they should be used. The experts conclude that the DNA and RNA tests had high sensitivity for detecting colorectal cancer and moderate sensitivity for detecting advanced precancerous lesions that are about to turn into cancer. The blood tests, on the other hand, showed lower sensitivity for both advanced precancerous lesions and stage 1 cancers.

"While colorectal screening blood tests may not be as effective as other options, they are certainly better than not screening," Wolf said. "So if a patient declines a stool test or a visual exam like a colonoscopy, a blood test would be the way to go, as long as the patient understands it is not as effective, and, if it is positive, they will still need to have a colonoscopy."

Based on their results, the experts endorse the stool tests for patients at average risk but urge doctors to reserve the blood tests for patients who refuse other screening options. And they recommend that anyone who tests positive on any stool or blood test should receive a colonoscopy promptly.

It's important, they note, that doctors explain to patients the strengths and weaknesses of the available tests so that patients can make informed decisions.

"Currently, almost a third of adults are not up to date with colorectal cancer screening, and among those ages 45 to 49, it's twice that number," Wolf said. "We hope these new options will help to close this gap. The most important message is that colorectal cancer is a disease you don't have to die from, and there's a screening test out there that's right for you."

Better preventing, detecting and treating cancer is the core mission of UVA Comprehensive Cancer Center, one of only 57 cancer centers in the nation to earn the prestigious "comprehensive" designation from the National Cancer Institute. That designation is awarded only to elite cancer centers with the most outstanding cancer care and research programs in the country.

Guidelines published

The ACS researchers have published the new colorectal cancer guidelines online. The expert panel consisted of Wolf, Richard M. Hoffman, Louise C. Walter, Charnita Zeigler-Johnson, Timothy R. Church, Carmen E. Guerra, Elena B. Elkin, Ruth Etzioni, AbbeHerzig, Kevin C. Oeffinger, Rebecca B. Perkins, Sana Raoof, Ya-Chen Tina Shih, Steven J. Skates, Tyler B. Kratzer, Deana Manassaram-Baptiste and Robert A. Smith.