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New Fecal Test for Colorectal Tumors

A new fecal test that detects mutations in the APC gene may be useful in screening for colorectal cancer.

Evidence is mounting that stool DNA testing can identify colonic neoplasia with respectable accuracy (JW Dec 15 2000, p. 189, accession number 001121001, and Gastroenterology 2000; 119:1219). In this study, researchers tested fecal specimens for mutations in the adenomatous polyposis coli (APC) gene; such mutations initiate neoplasia in both familial and sporadic colorectal cancer. The researchers used an assay called digital protein truncation, in which abnormal polypeptides were generated in vitro if fecal DNA harbored APC mutations.

Stool specimens were obtained from 28 patients with nonmetastatic colorectal cancer (all Dukes' stage B2), 18 patients with adenomatous polyps that measured at least 1 cm in diameter, and 28 controls with no lesions detected by colonoscopy. APC mutations were found in 17 of the 28 cancer patients (sensitivity, 61%) and in 9 of the 18 adenoma patients (sensitivity, 50%). In contrast, none of the controls had APC mutations (specificity, 100%).

Comment: Fecal testing for APC mutations was moderately sensitive and highly specific for colorectal neoplasia. During the next few years, further refinements of fecal testing for genetic mutations undoubtedly will occur. The obvious goal is to develop a reliable screening tool that will be much more accurate than fecal occult blood testing.

— Allan S. Brett, MD

Published in Journal Watch General Medicine February 8, 2002

Citation(s):

Traverso G et al. Detection of APC mutations in fecal DNA from patients with colorectal tumors. N Engl J Med 2002 Jan 31; 346:311-20.

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