U.S. greenlights 1st blood test for colon cancer. How does it work?

U.S. health regulators on Monday approved a first-of-its-kind blood test for colon cancer, offering a new way of screening for a leading cause of cancer deaths.

Test manufacturer Guardant said the Food and Drug Administration approved its Shield test for screening in adults 45 and older who have an average risk of colon cancer. The test isn’t a replacement for colonoscopies, but provides a noninvasive approach to screening.

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Doctors can already order Shield for patients as a laboratory test with an out-of-pocket price of $895. But FDA approval is expected to increase coverage by private and government insurance.

The test looks for DNA fragments shed by tumor cells and precancerous growths. In a study published in March, the test caught 83% of the cancers but very few of the precancerous growths found by colonoscopy, the gold standard for colon cancer screening. The test missed 17% of cancers, performance that is on par with stool-based tests.

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Besides spotting tumors, colonoscopies can prevent the disease by removing precancerous growths called polyps.

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But some people avoid the exam because of the hassle of getting time off work or the day-ahead preparation that involves drinking a strong laxative to empty the bowels. In the U.S., screening is recommended for healthy adults ages 45 to 75 at average risk for colon cancer.

Physicians will be able to run the Shield test after taking a simple blood draw, Guardant said in a statement. The company plans to launch its product “in the near future.”

The annual rate of U.S. colon cancer screening is nearly 60%, well short of the 80% of age-eligible adults goal set by the American Cancer Society and other groups.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.