New DNA test helps detect colon cancer early

Results of a clinical trial of Cologuard show unprecedented rates of pre-cancer and cancer detection by a noninvasive test.

The detection rates are similar to those reported for colonoscopy.

Cologuard, is a noninvasive DNA test for the early detection of colorectal precancer and cancer. The Cologuard test is based on a stool sample that is analyzed for DNA signatures of precancer or cancer.

The clinical trial, called the DeeP-C study, included 10,000 patients and was designed to determine how well Cologuard detects precancer and cancer.

The study also compared Cologuard to the fecal immunochemical test for occult blood (FIT). The study was conducted at 90 medical centers throughout the United States and Canada.

Study's author David Ahlquist M.D., a Mayo Clinic gastroenterologist and co-inventor of the Cologuard test, said Cologuard detection rates of early stage cancer and high-risk precancerous polyps validated in this large study were outstanding and have not been achieved by other noninvasive approaches.

In the study, all patients received Cologuard, FIT and colonoscopy. Colonoscopy was the reference method. Major findings reported in the study include:

Sensitivity of Cologuard for cancer was 92 percent overall, and 94 percent for the earliest and most curable cancer stages (stages I and II).

Sensitivity was 69 percent for precancerous polyps at greatest risk to progress to cancer (i.e., those containing high-grade dysplasia).

The results have been published in the New England Journal of Medicine (NEJM).