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Rapid Responses to:
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Electronic letters published:
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The Role of the Fecal Occult Blood Test
In defense of the digital rectal exam and FOBT
Another Perspective
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Christian Jackson, M.D. Northwestern University, Robert Craig M.D.
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c-jackson5{at}northwestern.edu Christian Jackson, et al.
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Feb.8, 2005 The Role of Fecal Occult Blood Test TO THE EDITOR: We read with interest the article by Dr. Collins, et.al and the accompanying editorial by Dr. Sox(1,2).We share Dr. Sachs’s concern that there has not been a more rapid decrease in colon cancer mortality associated with the emphasis on increased screening over the past 10 years. We think this is multifactorial. We should like to respond to these observations before the digital rectal examination stool for occult blood is abandoned. One reason for this might be the replacement of flexible sigmoidoscopy for total colonoscopy for people of low risk for colon carcinoma. With the exception of the Veterans Administration Health systems, this practice has produced a chasm between those that can afford total colonoscopy or insist upon it versus those who cannot. A paucity of any screening intervention in the African-American and Hispanic populations is troubling because there are more datum available which show that African-Americans and Hispanics have an increased incidence in the diagnosis of colon cancer when compared to Caucasians(3,4). One reason for this failure among these populations may be the abandonment of testing for fecal occult blood. The authors stress that one stool analysis obtained by rectal examination showed a very low sensitivity for the detection of advanced neoplasia when compared to three stools spontaneously passed. The authors do not stress the fact that fecal occult blood testing is done annually, and that many of these advanced neoplasms would be picked up on subsequent annual examinations, no matter what aspect of the stool is tested. We therefore support any and all fecal occult blood testing, with the caveat that rectally obtained stool should be used only if stool is obtained and should not be tested if visible blood is present. Some screening is better than no screening at all. Christian S. Jackson M.D. Robert Craig M.D. Northwestern University, Feinberg School of Medicine Chicago,IL 60611-290 References 1.Collins, Judith F. MD; Lieberman, David A. MD; Durbin, Theodore E. MD; Weiss, David G. PhD. Accuracy of Screening for Fecal Occult Blood on a Single Stool Sample Obtained by Digital Rectal Examination: A Comparison with Recommended Sampling Practice. Annals of Internal Medicine.2005;142(2):81-85 2.Sox, Harold C. Office-Based Testing for Fecal Occult Blood: Do Only in Case of Emergency.Annals of Internal Medicine. 2005;142(2):146-148 3.Jemal A, Murray T, Samuels A, et.al Cancer statistics, 2003. CA Cancer J Clin. 2003; 53:5-26 4.Chao A, Gilliland F, Hunt W, Bulterys M, Becker T, Key C. Increasing incidence of colon and rectal cancer among Hispanics and American Indians in New Mexico( United States),1969-94.Cancer Causes and Control.1998;9:137-144 Conflict of Interest:None declared |
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Christopher A Smith, MD Cook County Hospital, Chicago, IL
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christopher_smith{at}rush.edu Christopher A Smith
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Dear Editors I read with interest the study by Collins et al which seems to provide convincing evidence that using a single stool sample obtained by digital rectal exam is an unreliable method of screening for colorectal neoplasia. However, I propose that there is one situation in which performing this test maybe clinically useful. Using data from the authors the Likelihood Ratio for both the single FOBT and the 6-sample FOBT being positive is 7.5. Admittedly this did not occur very often, but I propose that clinicians should perform a rectal exam and FOBT when a patient presents with a positive 6-sample FOBT. One reason is to exclude a rectal mass and the second is that if the digital FOBT sample is also positive (using a LR of 7.5) the post-test probability of a colorectal neoplasm rises from about 10% to 45%. In any situation a positive FOBT should be followed up with a colonoscopy, but faced with an approximately 50:50 chance of malignancy the situation I described gives the matter some urgency. Yours truly Christopher A. Smith, MD Conflict of Interest:None declared |
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Robert C. Kane, MD, FACP None
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rckane{at}pol.net Robert C. Kane
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In the study by Collins et al, the initial group of 3100 became 2600 analytic cases. Some of these may represent non-compliant patients who did not complete the FOBT process. The authors should have used the intention- to-study (ITT) population for the denominator. Second, clinicians may be doing the single FOBT with the rectal exam YEARLY. Thus, this study might have examined the question: "How does the health outcome of a single FOBT test (6 samples) compare with 6 annual rectal exams including a single FOBT test each year?" Given that these were asymptomatic subjects who would only need a colonoscopy every 10 years (assuming no interval findings), a single FOBT annually as part of the rectal exam might have merit and circumvent the non-compliant "home-tester." Conflict of Interest: None declared Conflict of Interest:None declared |
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