Gastroenterology

Gastroenterology

Volume 119, Issue 5, November 2000, Pages 1219-1227
Gastroenterology

Alimentary Tract
Colorectal cancer screening by detection of altered human DNA in stool: Feasibility of a multitarget assay panel,☆☆,

Presented in part at the annual meeting of the American Gastroenterological Association in Orlando, Florida, in May 1999 (Gastroenterology 1999;116:A369).
https://doi.org/10.1053/gast.2000.19580Get rights and content

Abstract

Background & Aims: Assay of altered DNA exfoliated into stool represents an intriguing approach to screen for colorectal neoplasia, but multiple markers must be targeted because of genetic heterogeneity. We explored the feasibility of a stool assay panel of selected DNA alterations in discriminating subjects with colorectal neoplasia from those without. Methods: Freezer-archived stools were analyzed in blinded fashion from 22 patients with colorectal cancer, 11 with adenomas ≥1 cm, and 28 with endoscopically normal colons. After isolation of human DNA from stool by sequence-specific hybrid capture, assay targets included point mutations at any of 15 sites on K-ras, p53, and APC genes; Bat-26, a microsatellite instability marker; and highly amplifiable DNA. Results: Analyzable human DNA was recovered from all stools. Sensitivity was 91% (95% confidence interval, 71%–99%) for cancer and 82% (48%–98%) for adenomas ≥1 cm with a specificity of 93% (76%–99%). Excluding K-ras from the panel, sensitivities for cancer were unchanged but decreased slightly for adenomas to 73% (39%–94%), while specificity increased to 100% (88%–100%). Conclusions: Assay of altered DNA holds promise as a stool screening approach for colorectal neoplasia. Larger clinical investigations are indicated.

GASTROENTEROLOGY 2000;119:1219-1227

Section snippets

Design and subjects

The investigation was approved by the Mayo Clinic Institutional Review Board and comprised 2 clinical pilot studies. Stools for each were selected from a freezer archive to yield subject groups with verified colorectal adenocarcinoma, colorectal adenomas ≥1.0 cm, and colonoscopically normal colons. Subjects were chosen to provide a balanced age and gender representation across groups and a mixed distribution of neoplasms from both proximal and distal colorectal sites (Table 1).Most patients

Results

Analyzable human DNA was recovered in all subjects. When detected, mutant DNA accounted for 1%–24% of total human DNA recovered in stools from cancer patients and for 1%–7% from those with large adenomas.

Discussion

The rationale and appeal of stool screening for colorectal cancer would be strengthened if markers substantially more accurate than occult blood were used. On the basis of this pilot investigation, the aggregate assay of multiple genetic markers exfoliated into stool represents a promising alternative. The panel of neoplasm-associated DNA alterations targeted in this study highly discriminated patients with colorectal cancer or large adenomas from those with endoscopically normal colons.

The

Acknowledgements

The authors thank Drs. Bert Vogelstein and Kenneth W. Kinzler of Johns Hopkins University Oncology Center and Howard Hughes Medical Institute for helpful comments through the course of this study; Joy Yucaitis for extensive logistical support; Jaci McCormick, Mary Devens, Joel Swenson, and Nancy Diehl for valuable database support; Dr. Lawrence Burgart for pathology review; and Drs. Steven J. Laken and Barry Berger for contributions to technical aspects of assay interpretation and critical

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    Address requests for reprints to: David Ahlquist, M.D., Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905. e-mail: [email protected]; fax: (507) 266-0350.

    ☆☆

    Supported by grants from the National Cancer Institute of National Institutes of Health (R01 CA 7160), EXACT Laboratories (Maynard, MA), and Mayo Foundation (Rochester, MN) and by the philanthropic support of Charles W. Oswald.

    Mayo Foundation is a minor equity investor in EXACT Laboratories. D. Ahlquist is a member of EXACT Laboratories' Scientific Advisory Board but holds no stock and has received no consulting fees. J. Harrington and D. Mahoney have no affiliation with EXACT Laboratories. A. Shuber, J. Skoletsky, W. Pierceall, and K. Boynton are employees of EXACT Laboratories.

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