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MARKET PULSE

Shares of Guardant Health Inc. tanked 40% and shares of Exact Sciences Corp. rallied more than 25% in the extended session Thursday after Guardant announced results from a study using its blood test to screen for colorectal cancer that didn’t appear to surpass Exact Sciences’ stool-sample screening test. Guardant said that the results “pave the way for first potential FDA-approved and Medicare-reimbursed blood test for colorectal cancer screening,” and that it plans to ask for U.S. Food and Drug Administration approval in early 2023. Guardant’s test demonstrated 83% sensitivity in detecting individuals with colorectal cancer; Exact Sciences in January said that a second-generation version of its stool-sample test Cologuard showed overall sensitivity of 95.2% in detecting colorectal cancer.