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Noninvasive DNA test tops FIT at finding cancer.


A noninvasive, multitarget stool DNA test detected significantly more cancer than did a fecal immunochemical test in people at average risk for colorectal cancer, but had greater false-positive results, according to a report published in the New England Journal of Medicine.

The study's primary outcome was the ability of the DNA test to detect colorectal cancer. The secondary outcome was the DNA test's ability to detect advanced precancerous lesions, including advanced adenomas and sessile serrated polyps measuring 1 cm or more in diameter, compared with the performance of a commercially available fecal immunochemical test (FIT) for human hemoglobin.

The multitarget stool DNA test in eludes molecular assays for aberrantly methylated BMP3 and NDRG4 promoter regions, KRAS mutations, and beta-actin (a reference gene for human DNA quantity), as well as an immunochemical assay for human hemoglobin.


The researchers enrolled 12,776 asymptomatic persons aged 50-84 years who were scheduled to undergo a colonoscopy screening; of those participants, 9,989 could be fully evaluated. The study, at 90 sites in the United States and Canada from June 2011 to November 2012, was led by Dr. Thomas F. Impeliale of Indiana University, Indianapolis, and his associates.

The DNA test's sensitivity was greater than FIT's for detection of colorectal cancer (92.3% vs. 73.8%, respectively) and for advanced precancerous lesions (42.4% vs. 23.8%, respectively), the researchers noted (N. Engl. J. Med. 2014 [doi: 10.1056/ NEJMoal311194]). The difference could be from the DNA marker and algorithm components of the test, they noted, because both the DNA and FIT tests use almost identical hemoglobin immunoassay components.

The DNA test's sensitivity for the detection of advanced precancerous lesions was approximately half that for the detection of colorectal cancer. DNA testing was more sensitive than was FIT for the detection of lesions with high-grade dysplasia (69.2% vs. 46.2%; P = .004) and sessile serrated polyps 1 cm or larger (42.4% vs. 5.1%; P less than .001), and for the detection of advanced precancerous lesions within the size ranges observed, the investigators reported.

However, FIT was more specific for the detection of both colorectal cancer and advanced precancerous lesions, by absolute differences of 6.6%-8.3%, the authors noted.

"A noninvasive test with a high single-application sensitivity for curable-stage cancer may provide an option for persons who prefer noninvasive testing," the investigators concluded. However, "questions about testing intervals and tailoring require further consideration."

Exact Sciences funded the study. Dr. Impeliale reported receiving grant support from Exact Sciences.

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Author:Kern, Rebecca
Publication:Internal Medicine News
Date:Apr 1, 2014
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