FDA Approves Blood Test for Colon Cancer Screening

MedPage Today Article by Mike Bassett, Staff Writer, MedPage Today,July 29, 2024

The FDA approved the Shield blood test for colorectal cancer (CRC) screening in adults ages 45 and older at average risk for the disease, Guardant Health announced.

According to the company, the approval makes Shield the first blood test to be approved by the FDA as a primary screening option for CRC. Positive results should be followed by a colonoscopy.

In May, the FDA’s Molecular and Clinical Genetics Panel of the Medical Devices Advisory Committee endorsed the test’s safety and efficacy based on results from the ECLIPSE study, which showed that the cell-free (cf)DNA blood-based test had a sensitivity of 83% for CRC and a specificity of 90% for advanced neoplasia.

But committee members also expressed concern about the assay’s low sensitivity for advanced adenomas and called for strong labeling on the matter.

The full product information for Shield indicates that it “has limited detection (55%-65%) of stage I colorectal cancer and does not detect 87% of precancerous lesions.”

In announcing the approval, Guardant noted that the CRC screening rate in the U.S. is about 59%, which falls well below the National Colorectal Cancer Roundtable’s goal of 80% for eligible individuals.

“The persistent gap in colorectal cancer screening rates shows that the existing screening options do not appeal to millions of people,” said ECLIPSE investigator Daniel Chung, MD, of Massachusetts General Hospital and Harvard Medical School in Boston, in a statement.

“Approval of the Shield blood test marks a tremendous leap forward, offering a compelling new solution to close this gap,” he added. “This decision will help make screening tests more broadly accessible and propel blood-based testing and CRC screening into a new era. With increased screening rates and early cancer detection, many more lives can be saved.”

Co-investigator William Grady, MD, of the Fred Hutchinson Cancer Center in Seattle, noted that “this is a promising step toward making more convenient tools available to detect colorectal cancer early while it is more easily treated. The test, which has an accuracy rate for colon cancer detection similar to stool tests used for early detection of cancer, could offer an alternative for patients who may otherwise decline current screening options.”

ECLIPSE evaluated the cfDNA blood-based test in a population that included adults ages 45 to 84 who had an average risk for CRC and were undergoing routine screening with colonoscopy.

In the validation cohort of nearly 8,000 evaluable patients, the cfDNA blood-based test had a sensitivity of 88% for screening-relevant (stages I, II, or III) CRCs, with a sensitivity of 65% for stage I cancers, 100% for stage II cancers, and 100% for stage III cancers. The test also identified all 10 stage IV CRCs.

However, among the more than 1,000 participants with advanced precancerous lesions in the study, the cfDNA blood-based test had a sensitivity of only 13%.

Shield is available for eligible individuals by prescription through a doctor or other healthcare professional, and Guardant said the test is expected to be covered for eligible Medicare beneficiaries.

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