Detection of APC mutations in fecal DNA from patients with colorectal tumors

Abstract

Background: Noninvasive methods for detecting colorectal tumors have the potential to reduce morbidity and mortality from this disease. The mutations in the adenomatous polyposis coli (APC) gene that initiate colorectal tumors theoretically provide an optimal marker for detecting colorectal tumors. The purpose of our study was to determine the feasibility of detecting APC mutations in fecal DNA with the use of newly developed methods.

Methods: We purified DNA from routinely collected stool samples and screened for APC mutations with the use of a novel approach called digital protein truncation. Many different mutations could potentially be identified in a sensitive and specific manner with this technique.

Results: Stool samples from 28 patients with nonmetastatic colorectal cancers, 18 patients with adenomas that were at least 1 cm in diameter, and 28 control patients without neoplastic disease were studied. APC mutations were identified in 26 of the 46 patients with neoplasia (57 percent; 95 percent confidence interval, 41 to 71 percent) and in none of the 28 control patients (0 percent; 95 percent confidence interval, 0 to 12 percent; P<0.001). In the patients with positive tests, mutant APC genes made up 0.4 to 14.1 percent of all APC genes in the stool.

Conclusions: APC mutations can be detected in fecal DNA from patients with relatively early colorectal tumors. This feasibility study suggests a new approach for the early detection of colorectal neoplasms.