American Cancer Society adds blood test to colorectal cancer screening guidelines
The American Cancer Society (ACS) officially updated its colorectal cancer screening guidelines on Wednesday, 27 May 2026, expanding detection methods to include a simple blood test for adults aged 45 and above. The move aims to improve screening participation rates, as colorectal cancer is the leading cause of cancer deaths among adults under 50. Despite being preventable and treatable when caught early, around a third of eligible adults currently do not undergo regular screening.
The blood test in question, Shield, developed by Guardant Health, detects tumour DNA fragments. It received regulatory approval in 2024, but experts caution that its convenience comes with important medical caveats. According to the guidelines published in CA: A Cancer Journal for Clinicians, the blood test is only recommended for individuals who refuse or cannot undergo standard screening methods due to its lower accuracy in identifying pre-cancerous lesions compared to conventional tests.
William Dahut, ACS Chief Scientific Officer, stated that the most effective screening test is one patients actually complete. “If patients know this test isn’t very good at detecting stage 1 cancer or pre-cancer but still refuse other tests, they should do the blood test,” he said.
Ronald Driggers, 68, a retired crane operator, provides a real-world example. After years of refusing colonoscopies and discarding stool tests due to disgust, he agreed to the blood test in late 2024. A positive result led to a colonoscopy that revealed stage 3 colorectal cancer.
While ACS guidelines are influential, they do not automatically determine insurance coverage. Under the Affordable Care Act, insurance mandates follow recommendations from the US Preventive Services Task Force, which currently does not endorse blood-based tests for routine screening.
Doctors also warn of risks where patients with positive blood or stool tests fail to proceed to the essential colonoscopy procedure, which is necessary to remove polyps before they become deadly. Colorectal cancer is estimated to cause nearly 160,000 new diagnoses and 55,000 deaths annually in the US. While the blood test offers hope for earlier detection, in-depth discussions between doctors and patients remain crucial.