Guardant Health’s Shield Blood Test Shows Higher Colorectal Cancer Screening Adherence and More Deaths Averted Than Stool-Based Tests
Guardant Health, a leading precision oncology company, has announced new research highlighting the potential role of blood-based testing in improving colorectal cancer (CRC) screening participation and follow-up colonoscopy adherence. The findings, presented with research collaborators at the American College of Gastroenterology (ACG) 2026 Annual Meeting in Nashville, Tennessee, examine how blood-based screening may help address persistent gaps in colorectal cancer prevention and early detection.
The research focuses on Guardant Health’s Shield blood test, which is designed to provide a non-invasive screening option for average-risk adults eligible for colorectal cancer screening. According to the company, the new findings indicate that blood-based screening may help bring more people into the screening process while supporting the follow-up procedures needed to identify and investigate potential cancer risks.
Colorectal cancer remains an important public health concern because screening participation and timely follow-up can influence whether the disease is detected before it progresses. Although established screening methods are available, some individuals do not complete recommended tests because of concerns about convenience, preparation requirements, access to healthcare services, or other practical barriers.
Blood-based testing may offer an additional option for people who are reluctant to complete stool-based screening or other recommended procedures. By making screening more accessible to individuals who might otherwise remain unscreened, this approach could help increase participation and identify more people who require further evaluation.
The newly presented research includes a modeling study comparing the projected lifetime health outcomes of blood-based screening with two stool-based approaches: the fecal immunochemical test (FIT) and multitarget stool DNA (mt-sDNA) testing. The study incorporated longitudinal screening adherence and real-world follow-up colonoscopy adherence to estimate the potential effects of the different screening strategies.
The model projected that blood-based screening could result in more colonoscopies and more colorectal cancer deaths averted than the two stool-based testing approaches among 1,000 simulated individuals over their lifetimes.
According to the reported results, blood-based screening was associated with 679 colonoscopies and 12 colorectal cancer deaths averted, compared with 113 colonoscopies and six deaths averted for FIT and 326 colonoscopies and nine deaths averted for mt-sDNA testing.
These results suggest that a screening method’s overall impact depends not only on its clinical characteristics but also on whether eligible individuals complete testing and follow the recommended next steps.
Modeling Study Examines Long-Term Screening Outcomes
The modeling study evaluated individuals between the ages of 45 and 75 and projected health outcomes across their lifetimes. The analysis compared blood-based screening with FIT and mt-sDNA testing while accounting for real-world adherence to follow-up colonoscopy.
Colorectal cancer screening often involves several stages. An eligible individual must complete an initial screening test, receive and understand the result, and undergo further evaluation when indicated. Depending on the screening method and findings, colonoscopy may be necessary to investigate abnormalities, identify precancerous growths, or diagnose cancer.
When individuals do not complete the initial screening test, they may miss an opportunity to identify potential problems. Similarly, when a screening result requires further evaluation but the patient does not complete a recommended colonoscopy, the benefits of the initial test may be reduced.
The modeling analysis sought to account for these practical factors when estimating the long-term consequences of different screening approaches.
Based on the results reported by Guardant Health, blood-based screening was associated with the highest projected number of colonoscopies among the three strategies. The model estimated 679 colonoscopies per 1,000 simulated individuals over their lifetimes for blood-based screening, compared with 113 for FIT and 326 for mt-sDNA testing.
The analysis also projected that blood-based screening would avert 12 colorectal cancer deaths per 1,000 simulated individuals, compared with six for FIT and nine for mt-sDNA testing.
These estimates suggest that improving initial screening participation can increase the number of people who proceed to appropriate follow-up procedures. In this context, a greater number of colonoscopies may reflect increased participation in the screening pathway rather than an undesirable increase in medical procedures.
However, the results are projections from a modeling study, not observations of deaths prevented in a randomized clinical trial. The estimated outcomes depend on the assumptions used in the model, including screening adherence, follow-up behavior, and the performance of the screening strategies being compared.
The findings therefore provide a basis for examining how real-world participation influences long-term screening outcomes, rather than establishing that one testing approach will produce the same results for every population.
Rural Health Clinics Report 99% Real-World Adherence
In addition to the modeling research, Guardant Health highlighted a clinical implementation study examining the use of Shield in two rural health clinics in South Carolina.
The study reported a real-world adherence rate of 99% for the blood-based screening approach. Guardant Health compared this result with reported overall colorectal cancer screening adherence rates ranging from 28% to 71%.
The findings are particularly relevant to rural and medically underserved communities, where patients may face barriers that make preventive healthcare more difficult to access.
Those barriers can include limited availability of specialists, transportation difficulties, competing work and family responsibilities, concerns about invasive procedures, and challenges navigating healthcare services. Such factors can influence whether individuals complete recommended screening, even when they are eligible and understand the importance of early detection.
A blood test may offer a more convenient option for some patients because it can be incorporated into a healthcare visit without requiring the patient to collect a stool sample at home. Depending on the clinical setting, this may help reduce certain practical obstacles to completing an initial screening test.
The reported 99% adherence result suggests that Shield was highly acceptable to the patients included in the two-clinic implementation study. Nevertheless, the result should be interpreted in the context of the study’s specific population, clinical setting, and measurement methods. It should not automatically be assumed that the same adherence rate will be achieved across every healthcare system or patient group.
The findings build on earlier real-world evidence cited by Guardant Health, including a 2025 study conducted in Appalachia. The company has continued to examine whether blood-based screening can help reach individuals who might otherwise remain outside established colorectal cancer screening programs.
Together, these studies emphasize the importance of considering patient participation alongside test performance when evaluating strategies to expand preventive care.
Guardant Health Highlights the Importance of Follow-Up Colonoscopy
Sam Asgarian, Vice President of Clinical Affairs at Guardant Health, said the new research builds on the company’s real-world evidence concerning blood-based colorectal cancer screening.
“Today’s research continues to reinforce the data we’ve seen across Guardant’s robust real-world evidence: blood-based screening meaningfully closes gaps in colorectal cancer screening participation with a significant lift in underserved communities that face some of the most persistent access barriers,” Asgarian said.
He explained that the latest research connects real-world screening adherence and follow-up colonoscopy behavior with modeling studies evaluating the potential impact of the Shield blood test.
Asgarian added that the company is pleased to present the research with its collaborators at the ACG meeting and demonstrate the potential role of Shield as an alternative to traditional screening methods.
The emphasis on follow-up colonoscopy is important because screening does not end when an initial test is completed. If a screening result indicates that additional evaluation is needed, timely diagnostic follow-up can be essential to determining whether a patient has cancer or another condition requiring treatment.
Improving adherence to the initial screening test may therefore create more opportunities to identify patients who need further assessment. However, screening programs must also ensure that patients have access to appropriate follow-up services and understand the next steps required by their results.
Health systems considering blood-based screening may need to coordinate patient education, test ordering, result communication, referral processes, and colonoscopy access to ensure that increased screening participation translates into meaningful clinical benefits.
The modeling study’s results reinforce this point by showing that projected outcomes differ when real-world screening and follow-up behaviors are taken into account.
Shield Designed to Address Colorectal Cancer Screening Gaps
Guardant Health developed Shield to help address gaps in colorectal cancer screening participation. The company describes it as the most clinically validated blood test in its market and says it is the first blood test to receive approval from the U.S. Food and Drug Administration (FDA) as a primary screening option for colorectal cancer in average-risk adults aged 45 and older.
The test offers a blood-based alternative within the available screening landscape. According to Guardant Health, more than 200,000 Shield tests have been performed in real-world settings, and the company reports screening adherence above 90% across practice and health system settings.
These figures highlight the company’s focus on the practical challenge of getting eligible individuals to complete screening.
Several established screening options are available for colorectal cancer, including stool-based tests and colonoscopy. Each approach has different characteristics, requirements, and considerations for patients and healthcare professionals.
FIT is a stool-based test that detects signs of blood in a stool sample. Multitarget stool DNA testing evaluates stool samples for molecular markers associated with colorectal cancer and certain precancerous conditions. Both approaches can be used as non-invasive screening options, although they require patients to collect and submit samples.
Colonoscopy allows clinicians to examine the colon and rectum directly and, when appropriate, remove certain precancerous growths during the procedure. It can serve as a screening method and as a follow-up examination after certain non-invasive tests return abnormal results.
Blood-based screening provides another option for eligible individuals. Its potential value includes reaching people who may be unwilling or unable to complete other available tests.
However, screening methods are not interchangeable in every circumstance. The appropriate approach depends on factors such as the patient’s risk profile, medical history, screening guidelines, test limitations, and clinician recommendations. A negative result from a non-invasive screening test does not eliminate the possibility of colorectal cancer, and recommended follow-up procedures remain important when indicated.
Improving Screening Participation in Medically Underserved Communities
The research presented at ACG 2026 highlights the relationship between screening access and health outcomes, particularly among populations that experience persistent barriers to preventive care.
Medically underserved communities may face structural and logistical challenges that limit access to routine screening. Even when screening recommendations are widely available, participation can vary because of differences in healthcare access, provider availability, patient awareness, and the ability to complete the required procedures.
A blood-based test may help address some of these challenges by offering a screening option that can be discussed and administered in a clinical setting. For some patients, this approach may be easier to complete than collecting a stool sample or arranging a separate procedure.
If more eligible individuals complete screening, healthcare organizations may have more opportunities to identify abnormal results and arrange further evaluation. The effectiveness of this approach will depend on appropriate patient selection, accurate testing, communication of results, and access to diagnostic colonoscopy when needed.
The South Carolina clinic study provides a real-world example of how blood-based screening can be implemented in rural healthcare settings. Its reported 99% adherence rate offers encouraging evidence about patient participation in those clinics, although further research across additional populations and healthcare environments will be important for understanding how broadly the findings apply.
The modeling analysis provides a complementary perspective by estimating how differences in screening and follow-up adherence may influence lifetime outcomes. Taken together, the studies underscore the importance of evaluating screening strategies not only by their technical characteristics but also by their ability to reach people in everyday clinical practice.
Implications for Healthcare Systems and Preventive Care
The findings may be relevant to healthcare systems, primary care practices, and population health programs seeking to improve colorectal cancer screening completion.
Screening programs must balance clinical effectiveness, patient preferences, operational resources, and the ability to provide appropriate follow-up care. A test that is clinically useful but rarely completed by eligible patients may have limited population-level impact.
Conversely, an accessible screening option may help expand participation, provided that the test is appropriate for the patient and that follow-up requirements are addressed.
For healthcare organizations, introducing an additional screening option may require staff education, updated clinical protocols, patient communication strategies, and systems for tracking test completion and follow-up procedures.
The reported findings suggest that blood-based screening could contribute to these efforts, particularly when used to engage eligible individuals who are overdue for screening or reluctant to complete other available options.
At the same time, healthcare organizations will need to consider the evidence supporting each screening method and ensure that decisions align with applicable clinical guidance. Comparative models can inform planning, but projected outcomes should be evaluated alongside real-world clinical evidence and the needs of individual patients.
Further research may help clarify how different screening strategies perform across populations, how adherence changes over time, and whether improvements in initial participation consistently lead to better long-term outcomes.
Blood-Based Screening Could Expand Access to Colorectal Cancer Prevention
Guardant Health’s latest research highlights the potential of its Shield blood test to improve colorectal cancer screening participation and support follow-up care.
The modeling study projected that blood-based screening could result in 679 colonoscopies and 12 colorectal cancer deaths averted per 1,000 simulated individuals over their lifetimes, compared with 113 colonoscopies and six deaths averted for FIT and 326 colonoscopies and nine deaths averted for mt-sDNA testing.
Separately, a clinical implementation study at two rural South Carolina health clinics reported a 99% real-world adherence rate for Shield. This finding adds to the company’s growing body of evidence concerning the use of blood-based testing in populations that may face barriers to traditional screening approaches.
Presented at the American College of Gastroenterology’s 2026 Annual Meeting, the research reinforces the importance of patient participation and follow-up care in colorectal cancer screening programs.
Although the modeling results are projections rather than direct evidence of comparative mortality outcomes in a clinical trial, they suggest that improving screening adherence could help more people enter the preventive care pathway and receive further evaluation when needed.
As healthcare providers continue to explore ways to expand access to preventive services, blood-based testing may offer an additional approach for reaching eligible adults. Its ultimate contribution will depend on appropriate clinical use, continued evidence generation, and the ability of healthcare systems to ensure that patients complete recommended follow-up care.
For Guardant Health, the findings support its continued effort to position Shield as an additional option in colorectal cancer screening, with a particular focus on improving participation and addressing persistent gaps in preventive healthcare.
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