Journal of the National Cancer Institute Advance Access originally published online on September 25, 2007
JNCI Journal of the National Cancer Institute 2007 99(19):1462-1470; doi:10.1093/jnci/djm150
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© The Author 2007. Published by Oxford University Press.
ARTICLES |
Screening for Colorectal Neoplasms With New Fecal Occult Blood Tests: Update on Performance Characteristics
Affiliations of authors: Division of Research, Kaiser Permanente Northern California Region, Oakland, CA (JEA, TRL, JPT, IST, WKZ, JVS); Division of Gastroenterology University of California, San Francisco General Hospital Campus, San Francisco, CA (JEA); Department of Gastroenterology, Kaiser Permanente Medical Center, Walnut Creek, CA (TRL, AMP); Department of Epidemiology, School of Public Health and Community Medicine, University of Washington, Seattle, WA (LCS); Department of Medicine, Kaiser Permanente Medical Center, Richmond, CA (TC); Department of Medicine, Kaiser Permanente Medical Center, Sacramento, CA (MPP); Department of Internal Medicine, Kaiser Permanente Medical Center, San Francisco, CA (LS); Department of Medicine, School of Medicine; Health Care Systems Department, The Wharton School; Leonard Davis Institute of Health Economics; Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, PA (JSS); Departments of Medicine and Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC (DFR)
Correspondence to: James E. Allison, MD, Division of Research, Kaiser Permanente Northern California Region, 2000 Broadway, Oakland, CA 94612-2304 (e-mail: jea{at}dor.kaiser.org or jallison{at}medsfgh.ucsf.edu).
Background: One type of fecal occult blood test (FOBT), the unrehydrated guaiac fecal occult blood test (GT), is recommended by the United States Preventive Services Task Force and the Institute of Medicine for use in screening programs, but it has relatively low sensitivity as a single test for detecting advanced colonic neoplasms (cancer and adenomatous polyps 
1 cm in diameter). Thus, improving the sensitivity of FOBT should make colon cancer screening programs that use these tests more effective.
Methods: We assessed prospectively the performance characteristics of two newer FOBTs in 5841 subjects at average risk for colorectal cancer in a large group–model managed care organization. The tests evaluated included a sensitive GT, a fecal immunochemical test (FIT), and the combination of both tests. Patients with positive and negative test results were advised to have colonoscopy and sigmoidoscopy, respectively. Sensitivity and specificity for detecting advanced neoplasms in the left colon within 2 years after the FOBT screening were evaluated for the two tests administered separately and in combination.
Results: A total of 139 patients were diagnosed with advanced colorectal neoplasms (n = 14 cancers, n = 128 adenomas) within the 2 years following their initial FOBT screening. Sensitivity for detecting cancer was 81.8% (95% confidence interval [CI] = 47.8% to 96.8%) for the FIT alone and 64.3% (95% CI = 35.6% to 86.0%) for the sensitive GT and the combination test. Sensitivity for detecting advanced colorectal adenomas was 41.3% (95% CI = 32.7% to 50.4%) for the sensitive GT, 29.5% (95% CI = 21.4% to 38.9%) for the FIT, and 22.8% (95% CI =16.1% to 31.3%) for the combination test. Specificity for detecting cancer and adenomas was 98.1% (95% CI = 97.7% to 98.4%) and 98.4% (95% CI = 98.0% to 98.7%), respectively, for the combination test; 96.9% (95% CI = 96.4% to 97.4%) and 97.3% (95% CI = 96.8% to 97.7%), respectively, for the FIT; and 90.1% (95% CI = 89.3% to 90.8%) and 90.6% (95% CI = 89.8% to 91.4%), respectively, for the sensitive GT.
Conclusions: The FIT has high sensitivity and specificity for detecting left-sided colorectal cancer, and it may be a useful replacement for the GT.
| CONTEXT AND CAVEATS Prior knowledge The unrehydrated guaiac fecal occult blood test (FOBT), as a single test, is currently recommended for use in screening programs because it has been proven in randomized trials to decrease colorectal cancer mortality. Nevertheless, it has a somewhat low sensitivity for detecting colorectal cancer and advanced colorectal neoplasms. Study design The sensitivity and specificity of two newer FOBTs—a sensitive guaiac test (GT), which detects lower levels of the peroxidase activity of heme than the older test, and a fecal immunochemical test (FIT), which detects components of blood—to detect advanced adenomas and cancers in the left colon were compared in average-risk individuals. Contributions The FIT was more sensitive and specific than the sensitive GT for detecting cancer in the left colon. Implications The FIT might be more useful than the currently used FOBT for colorectal cancer screening. Limitations The newer tests were not directly compared with the currently recommended FOBT. The ability of the new tests to detect neoplasias of the right colon was not tested because not all patients were offered colonoscopy.
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Manuscript received January 31, 2007; revised July 9, 2007; accepted August 8, 2007.
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