Guardant Health Showcases Strong Shield Test Results Across 10 Cancer Types
At the 2025 Annual Meeting of the American Association for Cancer Research (AACR), Guardant Health, Inc. , a leader in precision oncology, unveiled compelling new data from a study evaluating its investigational blood-based multi-cancer detection (MCD) test, Shield™. The results revealed that the test achieved both high specificity and meaningful sensitivity across a broad spectrum of ten cancer types, with particularly notable performance in detecting some of the most lethal and difficult-to-diagnose cancers.
The findings, which were shared during an oral presentation titled “Evaluation of a plasma cell-free DNA methylation-based multi-cancer detection test,” highlight the Shield test’s capacity to not only detect cancer signals from cell-free DNA in blood plasma but also provide insights into the likely tissue of origin, or cancer signal of origin (CSO). The performance data played a critical role in the National Cancer Institute’s (NCI) decision to include the Shield MCD test in its forthcoming Vanguard Study — a national, multi-center trial that will explore the use of emerging technologies for early cancer detection in asymptomatic populations.
High Specificity and Performance Across Aggressive Cancers
In the study, the Shield test demonstrated an overall specificity of 98.5%, meaning it produced very few false positives — a key requirement for any screening tool intended for use in average-risk populations. Across all ten cancer types evaluated, the test achieved an overall sensitivity of 60%, indicating its ability to correctly identify individuals who have cancer. Notably, when examining only the six most aggressive cancers — those typically associated with poor survival outcomes and late-stage detection — the sensitivity climbed to 74%. These include esophageal-gastric, hepatocellular, lung, ovarian, and pancreatic cancers.
The ability to identify these aggressive cancers earlier through a non-invasive method like a blood test could mark a transformative advancement in oncology diagnostics. Many of these cancers lack established screening protocols or present with symptoms only at advanced stages, making early intervention exceedingly rare and survival rates dismal.
“This strong data reinforces the potential of the Shield test to detect multiple cancers earlier through a simple blood draw,” said AmirAli Talasaz, co-founder and co-CEO of Guardant Health. “This study was a critical step in evaluating this innovative technology as a new screening option we can bring to patients to help reduce cancer deaths.”
Study Design and Demographics
The data presented at AACR 2025 were generated from a blinded case-control study involving 778 participants aged 40 to 78 years (median age: 62), of whom 55% were female and 79% were white. Participants either had a confirmed diagnosis of cancer or were considered cancer-free based on self-reporting.
The study analyzed cell-free DNA (cfDNA) from blood plasma samples, focusing on cancer-specific methylation patterns — chemical modifications to DNA that can indicate abnormal cellular activity, such as malignancy. The methylation-based approach employed by the Shield test allows for the detection of molecular signatures linked to cancer with a high degree of precision.
Among the 403 participants who were part of the primary analysis cohort, the test’s overall accuracy for identifying the cancer signal of origin (CSO) — that is, the tissue where the cancer likely originated — reached 89%, offering physicians an additional tool to guide further diagnostic evaluation.
Sensitivity and CSO Accuracy by Cancer Type
Table 1 from the presentation broke down the sensitivity and CSO accuracy across the ten tumor types evaluated:
| Cancer Type | Sensitivity (%) | CSO Accuracy (%) |
|---|---|---|
| Esophageal-Gastric (Stomach) | 96% | 92% |
| Hepatocellular | 94% | 73% |
| Lung | 67% | 97% |
| Ovarian | 70% | 93% |
| Pancreas | 68% | 80% |
| Colorectal | 83% | 94% |
| Breast | 45% | 92% |
| Bladder | 62% | 75% |
| Prostate | 21% | 83% |
| Overall (All Types) | 60% | 89% |
These results highlight several important insights. The Shield test delivered especially high sensitivity for gastrointestinal-related cancers, such as esophageal-gastric (96%) and hepatocellular (94%), both of which are notorious for being diagnosed at late stages. Conversely, prostate cancer, which often progresses more slowly and may not shed as much tumor-derived cfDNA into the bloodstream, showed a lower sensitivity of 21%.
Despite the variance in sensitivity across tumor types, the consistently high specificity underscores the Shield test’s potential as a viable screening option that minimizes the risk of false positives — a common concern with any broad-based cancer detection method.
Academic and Industry Commentary
Commenting on the significance of the study, William Greenleaf, Ph.D., a professor of genetics at Stanford University School of Medicine and a study co-author, remarked: “Impressively, this initial cohort analysis of the Shield MCD test met overall performance expectations, with particularly strong sensitivity in the six most aggressive cancers for which early detection is key.”
Greenleaf, who also serves as a consultant to Guardant Health, emphasized the broader implications of these findings: “These results show this blood-based MCD test holds promise for detection of multiple cancer types, and thus for detection in asymptomatic adults when treatment is more effective.”
The Road Ahead: Vanguard Study and Regulatory Milestones
The Shield test’s inclusion in the NCI’s Vanguard Study marks an important validation step for Guardant Health as it looks to bring its MCD platform to clinical practice. The Vanguard Study, designed to lay the groundwork for a potential large-scale Cancer Screening Trial, will assess the real-world performance of blood-based cancer detection tools in diverse, asymptomatic populations.
If the Shield test continues to show strong performance in prospective, population-scale studies, it could eventually be positioned alongside — or in some cases, in place of — existing cancer screening modalities such as colonoscopy, mammography, and low-dose CT scans. Importantly, Shield could provide screening options for cancers that currently lack any standard early-detection tools.
Guardant’s Broader Precision Oncology Portfolio
The development of the Shield MCD test is part of Guardant Health’s broader mission to expand the utility of liquid biopsy in cancer care — from early detection to therapy selection, treatment monitoring, and recurrence surveillance. The company already offers several FDA-approved and CLIA-certified tests for advanced cancer patients, including Guardant360® for genomic profiling and Guardant Reveal™ for minimal residual disease (MRD) detection.
By investing in cutting-edge methylation detection technologies and building large-scale validation cohorts, Guardant is positioning itself as a leading player in the rapidly evolving landscape of early cancer diagnostics.
The unveiling of new Shield test data at AACR 2025 represents a meaningful step toward a future in which blood-based multi-cancer detection becomes a routine part of preventive care. With high specificity, promising sensitivity in aggressive cancers, and strong accuracy in identifying cancer origin, Guardant Health’s approach may soon empower clinicians and patients alike with earlier insights — and possibly save lives through timely intervention.
As Talasaz concluded, “We envision a future where a simple blood draw becomes the frontline of cancer screening — detecting disease before symptoms appear and enabling better outcomes through early action.”
