In a step that may redefine how Americans experience colorectal cancer (CRC) screening, the National Comprehensive Cancer Network (NCCN) has incorporated Guardant Health's Shield™ blood test in its updated clinical guidelines. This is the first time a blood test identifying circulating tumor DNA (ctDNA) has received such a recommendation for people with average risk who are age 45 and older.
The addition of Shield represents a turning point in preventive medicine. With colorectal cancer remaining the second leading cause of cancer-related death in the United States, experts think more widespread access to non-invasive, patient-friendly screening methods could increase participation and eventually save more lives.
A Patient-Centered Innovation for a Modern Age
Colonoscopy has been the gold standard for CRC screening for decades. It's very effective, but for many, bowel prep, anesthesia, or taking time off work is a turnoff. In fact, according to the CDC, almost 1 in 3 eligible adults are still not screened for colorectal cancer.
The Shield test is designed to do just that. Created by precision oncology firm Guardant Health, Shield is a straightforward blood test that detects ctDNA pieces associated with colorectal cancer. The method doesn't involve fasting, sedation, or diet restrictions, and can be done during an ordinary office visit.
"This is a significant milestone in getting more people into the screening paradigm," stated Dr. AmirAli Talasaz, Guardant Health's co-CEO. "Shield offers an additional choice for people who may otherwise put off or forego testing."
Science-Backed: The ECLIPSE Study
The NCCN's choice to approve Shield did not happen overnight. It came on the heels of the publication of the ECLIPSE study data, an extended clinical trial conducted in more than 20,000 patients. Released earlier this year, the findings revealed that Shield identified 83% of colorectal cancer in the average-risk population with a specificity of 90%.
This degree of performance makes the test comparable to much of what is currently available in non-invasive options, such as fecal immunochemical tests (FIT). But Shield's greatest selling point is how easy it is, merely a simple blood draw so it is an attractive option for providers and patients alike.
"Having an accurate blood test available is a game-changer," stated Dr. Richard Goldberg, former West Virginia Cancer Institute Director. "It has the potential for earlier detection and less late-stage diagnosis."
A Wider Movement Towards Fair Screening
The addition of Shield to the NCCN guidelines may also help reduce disparities in cancer screening. Research indicates that screening is less common among underprivileged populations, such as racial minorities and rural residents.
Not all patients have easy access to a GI clinic or are comfortable with colonoscopy," said Dr. Erica Spatz, Associate Professor at Yale School of Medicine. "Blood-based testing paves the way for more inclusive screening strategies."
Where Shield Fits in the Screening Ecosystem
The NCCN's revised guidelines suggest Shield for adults at average risk, 45 years of age and older. Notably, the test is not a substitute for diagnostic colonoscopy, particularly in individuals at higher risk or with symptoms such as rectal bleeding or unintended weight loss.
Shield, according to Guardant Health, is optimally utilized as a first-line screening tool. If it comes back positive, the colonoscopy still needs to be followed up. This tiered structure is in line with current screening workflows, but adds new flexibility to patients.
Shield also joins a list of increasing numbers of alternative CRC screening methods, like Cologuard (DNA testing on stool) and FIT kits, which have worked well for many. But its blood-based design makes it poised to be more scalable in primary care and employer settings.
Early Adoption and Reimbursement Prospects
Although the test was introduced in 2023, this NCCN endorsement is likely to drive Shield's use by providers and health systems. Clinical guidelines tend to drive both physician practices and payer coverage.
"Guideline inclusion is essential," stated Dr. David Lieberman, a prominent gastroenterologist and researcher. "It sends the message to clinicians that the test has evidence behind it and is suitable for widespread use."
Today, Shield is a cash-pay test that costs approximately $895. Guardant Health is in active discussions with commercial and government payers to gain reimbursement through insurance, especially in view of the NCCN update.
As of May 2025, the Centers for Medicare & Medicaid Services (CMS) has not yet provided formal coverage guidance. That being said, with the agency's recent approval of comparable non-invasive tests, most observers feel a positive decision will be forthcoming.
Market Implications: An Emerging Segment of Preventive Health
Cancer screening using blood is rapidly emerging as one of the most vibrant segments in healthtech. Industry experts predict that the global liquid biopsy market, at a present size of $5.5 billion in 2024, will reach more than $12 billion by 2030 on the back of early diagnosis and tailor-made therapy.
Guardant Health is already a leader in this field, with FDA approval for lung and breast cancer testing. The Shield test, while still laboratory-developed (LDT), represents a huge move into population-scale screening.
Aside from colorectal cancer, Guardant is also investigating Shield's potential for multi-cancer early detection (MCED), a game-changer for preventive oncology.
