A panel of
The FDA advisory panel voted 8-1 that the test is safe for people who meet the criteria for testing, 6-3 that the test is effective and 7-2 that the benefits of the test outweigh the risks.
Panelists raised concerns that Shield is not as accurate as colonoscopy screening.
In a study of nearly 8,000 patients, Shield detected 83% of cases of colorectal cancer. The test detected 88% of stage I, II or III colorectal cancer cases and around 13% of precancerous tumors called adenomas.
Comparatively, Exact's stool-based Cologuard test had 92.3% sensitivity rate, according to the FDA.
Panelist Dr.
"I think in the labeling, it should clearly indicate that this is not to detect adenomas and it is not designed as a preventive strategy," Spencer said.
Panel member Dr.
"My primary concern here is that I don't think Shield is a particularly good screening test for colon cancer," Brugge said, adding that he thinks "many of the other existing tests" are better.
The FDA will review the panel discussions and voting outcomes in deciding whether or not to approve the test.
If approved, Shield will be the second-blood-based test for colon cancer in
Dr.
Colonoscopy is considered the most accurate way to test for colorectal cancer, as it can detect lesions or polyps in the colon or rectum, whereas a blood test cannot. Many people, however, skip screening because the process is invasive.
"Most people would like to see a blood-based option that was more accurate with respect to finding precursor lesions in addition to cancers," he said. "But the rather remarkable thing about colorectal cancer screening is that people vary in their readiness to do one test or another. You have to give people a choice."
Panelist
Guardant argued that, because its test can be used easily and frequently, there is a higher chance that dangerous polyps can be detected, even with the test's lower detection rate.
About 150,000 Americans every year are diagnosed with colon and rectal cancers, and over a third of those cases are expected to be fatal.
Dr.
Regarding blood-based tests, Brahmbatt said, "The hope is, once approved by the
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