NEW TEST FOR COLORECTAL CANCER HAS HIGHER RATE OF FALSE POSITIVE RESULTS

By admin
March 10, 2015

Cologuard Pic

A Wisconsin company called Exact Sciences has launched a marketing campaign for its new product, Cologuard®, which it hails as “the breakthrough test for colon cancer screening that’s as easy as going to the bathroom.”

Although stool tests have been around for a while, Cologuard® is the first to use a person’s DNA, rather than blood, to spot tumors. The test was approved last August by the Food and Drug Administration.

“Exact Sciences admits Cologuard® isn’t an exact science,” notes Gastroenterologist Ronald P. Kotfila, M.D., with GI Associates, of Jackson, Vicksburg and Madison, MS.

In a full-page ad that ran in the New York Times, the company said that while the test can detect 92% of colon cancers, “both false positives and false negatives do occur.” And, that up to 13% of people tested were incorrectly diagnosed by Cologuard® as having potentially cancerous polyps. The rate of false positives for blood-based stool tests is no higher than 5%, researchers say.

According to Exact Sciences’ ad anyone testing positive with Cologuard® should confirm the result with a colonoscopy. It also said that anyone testing negative should still be regularly screened “with a method appropriate for the individual patient,” which in many cases means a colonoscopy.

This raises questions about the value of this “breakthrough test,” which Exact Sciences is pricing at about $600 per patient – compared with $25 for the traditional stool blood exam – and which, because of its newness, isn’t yet covered by most private insurance plans.

For more information about colorectal cancer visit www.gastro.org and www.cancer.org

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