FDA panel recommends a blood test for colon cancer

Advisers to the U.S. Food and Drug Administration on Thursday recommended for the approval of Guardant Health’s blood test to detect a cancer that begins in the colon or rectum.

The panel voted seven-to-two in favor of benefits outweighing risks when using the test called Shield for colorectal cancer.

If approved, Shield could become the second blood-based test for colon cancer diagnosis in the United States after Epigenomics’ Epi proColon, which was approved by in 2016.

Colon or rectal cancer occurs in about 150,000 patients in the U.S. annually and is the second-leading cause of cancer fatalities in the country, with more than 50,000 deaths each year, according to the FDA.

Currently, colonoscopy is considered the gold standard test for colon cancer, but adherence to it is low because it is invasive. Other tests include fecus-related test, such as Exact Sciences’ Cologuard, but blood-based tests are considered more convenient.

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Panelists raised concerns that Guardant’s test was not as accurate as colonoscopy, especially as Shield detected only 13% of pre-cancerous tumors called advanced adenomas.

This was also flagged by FDA’s staff reviewers in briefing documents released on Tuesday.

Guardant’s application for Shield was based on a study that showed the test detected 83% of colorectal cancers, while Exact’s Cologuard had 92.3% sensitivity rate, according to the FDA’s documents.

Shield “is better than nothing but I don’t want to downplay the issue that this test is going to miss a lot of cancers,” said Charity Morgan, panel member and professor in the department of biostatistics at University of Alabama.

The company expects the test will need to be repeated every one to three years, Guardant Health executive Victoria Raymond said at the meeting, but added that “colonoscopy should be the prioritized option.”

Reuters