The FDA has recently approved the Shield blood test for colorectal cancer (CRC) screening in adults ages 45 and older at an average risk for the disease. This new approval by the FDA makes Shield the first blood test to be approved as a primary screening option for CRC. It is important to note that positive results from the Shield blood test should be followed by a colonoscopy to confirm the findings.
The approval of the Shield blood test was based on results from the ECLIPSE study, which showed that the cell-free DNA blood-based test had a sensitivity of 83% for CRC and a specificity of 90% for advanced neoplasia. However, concerns were raised by committee members regarding the test’s low sensitivity for advanced adenomas. The product information for Shield also indicates that it has limited detection of stage I colorectal cancer and does not detect 87% of precancerous lesions.
Addressing the Screening Gap
Guardant Health, the company behind Shield, highlighted the fact that the CRC screening rate in the U.S. is only about 59%, falling well below the National Colorectal Cancer Roundtable’s goal of 80% for eligible individuals. According to ECLIPSE investigator Daniel Chung, MD, the existing screening options do not appeal to millions of people, leading to a persistence gap in colorectal cancer screening rates. The approval of the Shield blood test is seen as a significant step forward in closing this screening gap and making screening tests more broadly accessible.
Promising Advancements
Co-investigator William Grady, MD, mentioned that the approval of the Shield blood test is a promising step towards offering more convenient tools for detecting colorectal cancer early when it is more easily treatable. The test, which has a similar accuracy rate for colon cancer detection as stool tests used for early cancer detection, could provide an alternative for patients who may otherwise decline current screening options.
Study Results
The ECLIPSE study evaluated the cfDNA blood-based test in a population of 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 test showed a sensitivity of 88% for screening-relevant CRCs, with relatively high sensitivities for different stages of CRC. However, the test had a lower sensitivity of only 13% for advanced precancerous lesions, indicating a potential limitation in its effectiveness for detecting early-stage lesions.
Shield is currently available for eligible individuals by prescription through a doctor or other healthcare professional. Guardant Health has stated that the test is expected to be covered for eligible Medicare beneficiaries, making it more accessible to a wider population.
The approval of the Shield blood test for CRC screening represents a significant advancement in the field of early cancer detection. While the test shows promising results for detecting colorectal cancer at various stages, there are concerns about its sensitivity for detecting precancerous lesions. Continued research and monitoring will be essential to assess the long-term effectiveness and impact of the Shield blood test on improving CRC screening rates and ultimately saving lives.
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