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Although liquid biopsy would improve outcomes in currently unscreened people, substituting blood tests for a currently effective test would worsen patient outcomes and increase costs.

Liquid Biopsy Not Effective for Colorectal Cancer Screening

A blood test will be better than nothing, but may lead to more CRC cases and deaths than established screening tests

American Gastroenterological Association

The American Gastroenterological Association (AGA) is the trusted voice of the GI community. Founded in 1897, AGA has grown to include more than 16,000 members from around the globe who are involved in all aspects of the science, practice, and advancement of gastroenterology.

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Published:Mar 26, 2024
|2 min read
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BETHESDA, MD — Modeling studies and expert consensus published recently in Gastroenterology and Clinical Gastroenterology and Hepatology shed new light on the promise and peril of liquid biopsy for colorectal cancer (CRC) screening that are currently in development. “Based on their current characteristics, blood tests should not be recommended to replace established colorectal cancer screening tests, since blood tests are neither as effective nor cost-effective and would worsen outcomes,” said David Lieberman, MD, chair of the AGA CRC Workshop and lead author of an expert commentary on liquid biopsy for CRC screening. 

An AGA expert panel employed previously validated decision models to estimate the effects of a new blood-based CRC screening test on an average-risk population aged 45–75, assuming the test met minimal Centers for Medicare and Medicaid Services (CMS) criteria for CRC sensitivity (74 percent) and specificity (90 percent). The aim was to define the properties of successful CRC screening blood tests and compare possible outcomes with the established strategies of annual fecal immunochemical tests (FIT), triennial multitarget stool DNA tests (Cologuard), and 10-yearly colonoscopies.   

Key conclusions in the expert commentary, published in Clinical Gastroenterology and Hepatology

  • A blood test for CRC that meets minimal CMS criteria for sensitivity and performed every three years would likely result in better outcomes than no screening.  

  • A blood test for CRC offers a simple process that could encourage more people to participate in screening. Patients who may have declined colonoscopy should understand the need for a colonoscopy if findings are abnormal. 

  • Because blood tests for CRC are predicted to be less effective and more costly than currently established screening programs, they cannot be recommended to replace established effective screening methods. 

  • Although blood tests would improve outcomes in currently unscreened people, substituting blood tests for a currently effective test would worsen patient outcomes and increase costs. 

  • Potential benchmarks that the industry might use to assess an effective blood test for CRC going forward would be sensitivity for stage 1–3 CRC of >90 percent, with sensitivity for advanced adenomas of >40–50 percent. 

“Unless we have the expectation of high sensitivity and specificity, blood-based colorectal cancer tests could lead to false positive and false negative results, which are both bad for patient outcomes,” noted John Carethers, MD, AGAF, AGA past president and vice chancellor for health sciences at the University of California San Diego. 

- This press release was originally published on the American Gastrointestinal Association website