The FDA has approved Guardant Health’s new blood test, Shield, for colorectal cancer screening, making it eligible for Medicare coverage. This test detects “free-floating” fragments of cancer DNA in the bloodstream, offering a simpler and more convenient option compared to traditional methods, though it comes with reduced accuracy.
The ECLIPSE clinical trial, preceding FDA approval, showed Shield accurately confirmed 83.1% of colorectal cancer cases. While Shield is a noninvasive alternative to colonoscopies and stool-based tests, it does not replace these methods due to its lower accuracy rate. The trial included nearly 8,000 participants aged 45 to 84, and while Shield identified cancer in 83.1% of cases, 16.9% received false negatives.
Experts emphasize that while Shield is a significant advancement, it should be considered an adjunct rather than a replacement for colonoscopies. Dr. Daniel Chung from Massachusetts General Hospital highlights that existing screening methods do not appeal to millions, and Shield can help bridge this gap by providing a more accessible option. However, the potential for missed diagnoses remains a concern. Dr. Ben Park from Vanderbilt University points out the risk of false negatives, stressing that Shield should be used to complement, not replace, colonoscopies.
Shield does not test for precancerous lesions, detecting them in only about 13% of cases, which limits its use as a preventive measure. Despite these limitations, the test presents a new opportunity to increase screening adherence for colorectal cancer.
Guardant Health’s Shield blood test, now FDA-approved for Medicare coverage, offers a convenient, non-invasive screening option. However, it should be used alongside colonoscopies to ensure comprehensive colorectal cancer screening and detection.
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