AGA - American Gastroenterological Association Inc.

03/26/2024 | News release | Distributed by Public on 03/27/2024 15:00

AGA commentary offers reality check on blood-based colorectal cancer screening

Modeling studies and expert consensus published this week in Gastroenterologyand Clinical Gastroenterology and Hepatologyshed new light on the promise and peril of liquid biopsy (blood tests) for 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 or cost-effective, and would worsen outcomes."
David Lieberman, MDChair, AGA CRC Workshop
"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."
John Carethers, MD, AGAFAGA past president and vice chancellor for health sciences at the University of California San Diego
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An AGA expert panel set out 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 CMS criteria for CRC sensitivity (74%) and specificity (90%). The aim was to define properties of a successful CRC screening blood test and compare possible outcomes with the established strategies of FIT, MT-sDNA tests (Cologuard) and colonoscopies.

Here are the key conclusions found:

  • 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 cost.
  • Potential benchmarks that industry might use to assess an effective blood test for CRC going forward would be sensitivity for stage I-III CRC of >90%, with sensitivity for advanced adenomas of > 40-50%.