Frequently Asked Questions for Providers

Shield™ is a non-invasive, blood-based screening test that detects alterations associated with colorectal cancer in the blood. We apply a multimodal approach that analyzes genomic alterations and epigenomic modifications in cell-free DNA (cfDNA). Shield integrates these signals to produce an actionable result of either "Positive" or "Negative"¹

Simply because patients who are not up to date with screening are at greater risk of CRC mortality. In fact, a study found that over 75% of people who died of CRC were not up to date with screening. CRC remains the second-leading cause of cancer-related deaths in the US. For approximately 1/4 of patients, CRC is diagnosed after the cancer has metastasized, when the 5-year relative survival rate is low. A blood-based approach can improve these statistics and increase patient adherence by overcoming barriers associated with traditional screening options—colonoscopy and stool-based testing^2-5

Shield is indicated for colorectal cancer screening in individuals at average risk for the disease, age 45 years or older. Patients with a "Positive" result may have colorectal cancer or advanced adenomas and should be referred for colonoscopy evaluation. Shield is not a replacement for diagnostic colonoscopy or for surveillance colonoscopy of high-risk individuals. Shield has limited ability for the detection of advanced adenomas¹

Precaution

Based on data from clinical studies, Shield has limited detection (55%-65%) of Stage I colorectal cancer and does not detect 87% of precancerous lesions. One out of 10 patients with a negative Shield result may have a precancer that would have been detected by a screening colonoscopy. Shield demonstrated high detection of Stage II, III, and IV colorectal cancer.

Limitations

• Providers should discuss the most appropriate screening test to use with patients depending on their medical history and individual circumstances. The Shield test is not intended as a screening test for individuals who are at high risk for colorectal cancer.
• Shield has limited ability to prevent the development of colorectal cancer from advanced precancerous lesions and lower detection rates for Stage I colorectal cancer, given the current data available.
  • Shield has lower performance of stage I colorectal cancer [54.5% (12/22); 95% confidence interval (CI) (34.7%, 73.1%)]. The majority [6/10] of missed Stage I cancers were less than 10mm. Shield did not detect colorectal cancer lesions smaller than 10mm [0% (0/6); 95% CI 0.0% - 39.0%].
  • Shield may fail to detect as many as 88.7% of patients with advanced precancerous lesions which can later become neoplastic because of its limited ability for the detection of advanced adenomas [13.2% (147/1116); 95% CI (11.3, 15.3)].
  • Shield has a false negative rate of 17% for colorectal cancer, meaning 17 of 100 people who have colorectal cancer will incorrectly have a Shield negative result.
  • Shield has a false positive rate of 10%, meaning one of 10 people who do not have Advanced Neoplasia (colorectal cancer or advanced adenoma) will have a false positive test result.
• Colorectal cancer screening guideline recommendations vary for persons over the age of 75. The decision to screen patients over the age of 75 should be made on an individualized basis in consultation with a healthcare provider.
• A positive Shield test result suggests patients may have colorectal cancer or advanced adenoma. Patients with a positive result should be followed by colonoscopy.
• A negative Shield test result does not guarantee absence of colorectal cancer or advanced adenoma. Patients with a negative result should continue participating in colorectal cancer screening programs, at the appropriate guideline recommended intervals.
  • One out of 10 patients testing negative will be falsely reassured that they are negative for advanced adenoma, given the negative predictive value for advanced adenoma of 90%.
  • One out of 1000 patients testing negative will be falsely reassured that they are negative for colorectal cancer, given the negative predictive value of 99.9%.
• A false positive result may occur when the Shield test generates a positive result while a colonoscopy will not find colorectal cancer or advanced adenoma. A false negative result may occur when the Shield test does not detect a colorectal tumor signal while a colonoscopy identifies a colorectal cancer.
• The performance of Shield has been established in a prospectively designed, cross-sectional study. The benefits and risks of programmatic colorectal cancer screening (i.e., repeated testing over an established period of time) with Shield has not been studied.
• Non-inferiority or superiority of Shield sensitivity as compared to other recommended screening methods for colorectal cancer or advanced adenoma has not been established.
• Cross-reactivity was observed in analytical studies using samples from subjects with non-colorectal cancers, including gastric, pancreatic, liver, bladder, breast, lung, prostate, ovarian, melanoma and kidney cancers.
• Consult the Guardant Shield Blood Collection Kit (BCK) instructions for use (LBL-000324), for precautions and limitations specific to the collection and shipping of blood samples.

Colonoscopy should be discussed with all patients, given the test's ability to detect and potentially remove colorectal lesions. The Shield test can be considered in a manner similar to guideline-recommended non-invasive CRC screening options

It is important to share the benefits and risks of all options with your patients and work with them to find the option that is most appropriate for their overall health, prior screening history, preferences, and schedule. CRC screening adherence has been shown to improve when patients are educated on all their options through a shared decision-making process^6,7

Healthcare professionals can order Shield by filling out the form here. Please call 1.855.722.7335 or email ScreeningSupport@GuardantHealth.com to request more information

The Shield blood test received FDA approval on July 26, 2024, for CRC screening. It is the only FDA-approved CRC blood test with Medicare coverage. Eligible Medicare Part B or Fee for Service (FFS) patients will have $0 out-of-pocket cost for the Shield test. Medicare Advantage patients may be subject to co-pays, co-insurances, and deductibles, depending on their specific plan

Patients not covered by Medicare may have an out-of-pocket cost

We analyze Shield blood samples as soon as possible and deliver test results in ~2 weeks of receiving the samples in our lab

The ECLIPSE clinical study, published in the New England Journal of Medicine, was a large-scale colorectal cancer screening study that evaluated the performance of Shield, Guardant Health’s blood test for the detection of asymptomatic and early-stage CRC. The prospective, multi-site registrational study ECLIPSE compared Shield results with that of subsequent colonoscopy in 7861 average-risk patients between the ages of 45 and 84 at over 200 sites across the US. The study demographics were generally reflective of the US population, with above-average enrollment among Black Americans for a clinical study¹

The study demonstrated 83% sensitivity, 90% specificity, and 99.9% negative predictive value for Shield⁴

The data from this study were used to gain FDA approval and enable Centers for Medicare and Medicaid Services (CMS) coverage

Please click here to find more information about Shield data, including the ECLIPSE study publication from the March 14, 2024 issue of New England Journal of Medicine

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No special preparations are needed for patients since a simple blood draw is all that is required. This means that patients do not need to make dietary changes, undergo sedation, or take extra time away from work or family¹

• The USPSTF recommends screening for all eligible adults 45 to 75 years old for CRC⁸
• The USPSTF recommendations are classified into different grades below⁸
  • Grade A (adults aged 50 to 75 years) - “The USPSTF recommends screening for colorectal cancer in all adults aged 50 to 75 years”
  • Grade B (adults aged 45 to 49 years) - “The USPSTF recommends screening for colorectal cancer in adults aged 45 to 49 years”
  • Grade C (adults aged 76 to 85 years) - “The USPSTF recommends clinicians selectively offer screening for colorectal cancer in adults aged 76 to 85 years. Evidence indicates that the net benefit of screening all persons in this age group is small. In determining whether this service is appropriate for individual cases, patients and clinicians should consider the patient’s overall health, prior screening history, and preferences”

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