The American Cancer Society estimates that more than 150,000 people will be diagnosed with CRC in 2024 and the disease will be responsible for more than 53,000 deaths. More than 75% of individuals who die from CRC are not up to date with their screening.
Early detection is critical. When colon cancer is found at an early stage before it has spread, the five-year relative survival rate is 91%. If the cancer has spread to distant parts of the body, the five-year relative survival rate is 14%. Unfortunately, the CRC screening rate in the US is only 59%. This is largely because the preparation for colonoscopy is unpleasant, difficult to adhere to, and time-consuming.
The FDA has approved Guardant’s Shield blood test for colorectal cancer screening in adults age 45 and older who are at average risk for the disease. Approval was based on results of the ECLIPSE clinical trial. More than 20,000 adults, with average risk of CRC, were screened at 200 sites in rural and urban communities across 37 states. Shield had 83% sensitivity for detection of CRC. Specificity was 90% in both individuals without advanced neoplasia and in those who had a negative colonoscopy result. This test also demonstrated 13% sensitivity in detecting advanced adenomas.
Shield is a proprietary test based on next generation sequencing to detect genomic and epigenomic alterations in cell-free DNA (cfDNA) isolated from blood. The Shield test begins with the collection of whole blood in 4 Guardant cfDNA blood collection tubes. Specimens are then shipped to Guardant Health. Plasma is isolated from whole blood in each tube and then pooled. cfDNA is extracted from plasma for DNA sequencing. Epigenomic modifications may be detected as either altered methylation patterns in cfDNA sequence, or as changes in cfDNA fragment size distribution along the genome.
A library is prepared and enriched for informative genomic regions, followed by sequencing of the enriched library. The resulting cfDNA data are analyzed using proprietary bioinformatics algorithms designed to detect the presence of colorectal neoplasm-associated signals.
References
Chung DC, Gray DM, Singh H et al. A Cell-free DNA Blood-Based Test for Colorectal Cancer Screening. N Engl J Med 2024;390:973-83.
FDA Executive Summary, May 23, 2024, https://www.fda.gov/media/178792/download
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