Blood-Based Colorectal Cancer Screening Test Achieves 95% Patient Adherence in Real-World Study

A blood-based colorectal cancer (CRC) screening test demonstrated 95% patient adherence in a real-world analysis of 20,000 patients, according to data published in Current Medical Research and Opinion.

The Shield test, manufactured by Guardant Health, Inc, is the first blood test to receive Food and Drug Administration approval as a primary screening option for CRC in average-risk adults aged 45 years and older.

The analysis examined initial implementation of the blood-based screening test among patients with Shield clinical orders placed between May 2022 and June 2024. The 95% adherence rate exceeded reported adherence rates for colonoscopy and stool-based tests, which range from 25% to 71%. Median test turnaround time was 15 days from blood sample receipt to results report.

Appalachian Study Shows Screening Rate Increase

A separate study conducted in 2 primary care clinics in Appalachia—a region with low CRC screening rates and correspondingly high incidence and mortality rates—demonstrated that adding Shield as a screening option increased overall screening rates from 45% to 90%. The test achieved 98.5% adherence in this population, with positive patient and provider satisfaction.

"We continue to see compounding evidence that when patients are prescribed Shield, they are highly likely to complete the test in real-world clinical practice," Dr Craig Eagle, Guardant Health chief medical officer, said in a press release. "Through a simple blood draw, Shield is proving to be an accessible and pleasant option for physicians and patients."

Colorectal cancer is the second leading cause of cancer-related deaths in the US. Early-stage CRC carries a 91% 5-year survival rate, yet an estimated one in three eligible adults—more than 50 000 000 people—do not complete recommended screening. Many cite discomfort or inconvenience associated with colonoscopy or stool-based tests.

Shield uses a standard blood draw, which can be performed during any routine health care visit, potentially lowering barriers to test completion. Shield is covered by Medicare and the Veterans Affairs Community Care Network and is commercially available nationwide.

Shield detects blood-based alterations associated with CRC and is intended for average-risk adults aged ≥45 years. A positive result indicates concern for colorectal cancer or advanced adenoma and warrants referral for diagnostic colonoscopy. It is not intended for individuals at high risk of CRC.

References:

1. Graham-Adderton C, Guerra CE, Ngo-Metzger Q, Hoang T, Raymond VM. Implementation of blood-based colorectal cancer screening: real-world adherence and outcomes. Curr Med Res Opin. Published online November 8, 2025. doi:10.1080/03007995.2025.2582257
2. Shield CRC Blood Test Demonstrates Adherence of 95% in New Study of 20,000 Patients. News release. Guardant Health. November 5, 2025. Accessed November 19, 2025. https://investors.guardanthealth.com/press-releases/press-releases/2025/Shield-CRC-Blood-Test-Demonstrates-Adherence-of-95-in-New-Study-of-20000-Patients/default.aspx