A Quantitative Immunochemical Fecal Occult Blood Test for Colorectal Neoplasia

20 February 2007 | Volume 146 Issue 4 | Pages 244-255

Background: Guaiac-based fecal occult blood tests (FOBTs) for colorectal cancer screening are not specific for human hemoglobin and have low sensitivity. Automated-development, immunochemical FOBT is quality-controlled, is specific for human hemoglobin, and does not require diet restriction.

Objectives: To measure the sensitivity and specificity of quantitative immunochemical fecal hemoglobin measurements for detection of cancer and advanced adenoma in patients undergoing colonoscopy, to determine fecal hemoglobin thresholds that give the highest posttest probability for neoplasia, and to determine the number of immunochemical FOBTs needed.

Design: Prospective, cross-sectional study.

Setting: Ambulatory endoscopy services of the main health medical organization in Tel Aviv, Israel.

Participants: 1000 consecutive ambulatory patients—some asymptomatic but at increased risk for colorectal neoplasia and some symptomatic—who were undergoing elective colonoscopy and volunteered to prepare immunochemical FOBTs.

Intervention: The hemoglobin content of 3 bowel movements was measured, and the highest value was compared with colonoscopy findings.

Measurements: Sensitivity, specificity, predictive values, likelihood ratios, and 95% CIs of fecal hemoglobin measurements for clinically significant neoplasia, their relationship to the amount of fecal hemoglobin measured, and the number of immunochemical FOBTs performed.

Results: Colonoscopy identified clinically significant neoplasia in 91 patients (cancer in 17 patients and advanced adenomas in 74 patients). Using 3 immunochemical FOBTs and a hemoglobin threshold of 75 ng/mL of buffer, sensitivity and specificity were 94.1% (95% CI, 82.9% to 100.0%) and 87.5% (CI, 85.4% to 89.6%), respectively, for cancer and 67% (CI, 57.4% to 76.7%) and 91.4% (CI, 89.6% to 93.2%), respectively, for any clinically significant neoplasia.

Limitations: The fecal sampling method is standardized, but the sample size depends on fecal consistency. Some patients were tested while discontinuing aspirin and anticoagulant therapies. Study patients were at increased risk, and results might not apply to average-risk populations.

Conclusions: Quantitative immunochemical FOBT has good sensitivity and specificity for detection of clinically significant neoplasia. Test performance in screening average-risk populations is not known.

Editors' Notes Context Although screening with a guaiac-based fecal occult blood test (FOBT) reduces colorectal cancer mortality, better tests are needed. Contribution In the study, 1000 patients undergoing diagnostic colonoscopy provided fecal samples that a clinical laboratory tested with a quantitative immunochemical test for hemoglobin. Hemoglobin content was highest in samples from people with significant neoplasia, for which sensitivity and specificity were 67% and 91%, respectively. Positive and negative likelihood ratios were 7.8 and 0.36, respectively. Cautions The authors did not compare the immunochemical FOBT with guaiac-based FOBT. The study included people with symptoms. Implications The quantitative immunochemical test for fecal hemoglobin is a promising test that needs evaluation in a screening population. —The Editors

 

Author and Article Information

From Rabin Medical Center, Beilinson Hospital, Petach Tikva, Israel; Clalit Health Services, Tel Aviv and Bat-Yam, Israel; and Tel Aviv University Medical School, Tel Aviv, Israel.

Note: These results were presented, in part, at Digestive Diseases Week, Los Angeles, California, 20–25 May 2006.

Acknowledgments: The authors thank the medical and secretarial staff of the endoscopy units and the patients for their cooperation. They also thank Dr. Ester Shabtai and Doron Comaneshter for statistical analyses, Ms. Ziona Samuel for helping with patient enrollment, and Ms. Sally Zimmerman for secretarial assistance.

Grant Support: The Eiken Chemical Company, Alfa Wasserman, and Pharmatrade provided instruments and reagents. Research grants from the Eiken Chemical Company and the Katzman Family Foundation supported other costs.

Potential Financial Conflicts of Interest: Grants received: P. Rozen (Eiken Chemical Co.).

Requests for Single Reprints: Paul Rozen, MBBS, Department of Gastroenterology, Rabin Medical Center, Beilinson Hospital, 39 Jabotinsky Street, Petach Tikvah 49100, Israel; e-mail, paulro{at}clalit.org.il.

Current Author Addresses: Drs. Levi, Vilkin, and Niv; Ms. Hazazi; and Ms. Waked: Rabin Medical Center, Beilinson Campus, PO Box 85, Petach Tikva 49100, Israel.

Dr. Rozen: Department of Gastroenterology, Rabin Medical Center, Beilinson Hospital, 39 Jabotinsky Street, Petach Tikvah 49100, Israel.

Dr. Maoz: Clalit Health Services, Zamenhof Medical Center, 34 Zamenhof Street, Tel Aviv, Israel.

Dr. Birkenfeld: Clalit Health Services, Bat Yamon Medical Center, 33 Nusinson Street, Bat-Yam, Israel.

Dr. Leshno: Recanti Building, Tel Aviv University, Ramat Aviv, Israel.

Author Contributions: Conception and design: P. Rozen, Y. Niv.

Analysis and interpretation of the data: Z. Levi, P. Rozen, A. Waked, R. Hazazi, M. Leshno, Y. Niv.

Drafting of the article: P. Rozen, R. Hazazi, M. Leshno.

Critical revision of the article for important intellectual content: P. Rozen, M. Leshno, Y. Niv.

Final approval of the article: P. Rozen, R. Hazazi, A. Vilkin, S. Birkenfeld, Y. Niv.

Provision of study materials or patients: A. Vilkin, Z. Levi, E. Maoz, S. Birkenfeld, Y. Niv.

Statistical expertise: M. Leshno.

Obtaining of funding: P. Rozen, Y. Niv.

Administrative, technical, or logistic support: R. Hazazi, A. Vilkin, Z. Levi, A. Waked, Y. Niv.

Collection and assembly of data: Z. Levi, R. Hazazi, A. Vilkin, A. Waked.

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