Harold C. Sox, MD, Editor
Sox H.; Office-Based Testing for Fecal Occult Blood: Do Only in Case of Emergency. Ann Intern Med. 2005;142:146-148. doi: 10.7326/0003-4819-142-2-200501180-00014
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Published: Ann Intern Med. 2005;142(2):146-148.
Colorectal cancer is an important source of cancer mortality, ranking a close second behind lung cancer among types of cancer that affect both men and women (1). We know many details of the natural history and biology of colorectal cancer. We know that the gradual transition from small benign polyp to invasive malignancy takes several years, and molecular biologists have traced the accumulation of mutations that drive these changes. We know that we can reduce a healthy person's risk for death from colorectal cancer by inspecting the colonic mucosa and removing polyps and cancer. The proof of this principle is the association of screening sigmoidoscopy and reduced rates of death from cancer originating from the mucosa within reach of the sigmoidoscope, but not beyond it (2). It follows that screening colonoscopy should reduce deaths from cancer arising anywhere in the colon, but we have not proved that point conclusively. Several randomized trials have shown that the fecal occult blood test (FOBT) reduces the risk for death from colorectal cancer. In the trial with the longest follow-up, the 18-year colorectal cancer death rate was 14.1 deaths per 1000 patients with usual care and 9.5 deaths per 1000 patients with yearly FOBT (3).
February 18, 2005
Saved by the Brush: Approach for improving colorectal cancer
To the Editor:
The two articles (1,2) and accompanying editorial in the January 18, 2005 issue discredit the common practice of in-office screening for colorectal cancer. Dr. Harold Sox suggests "physicians may be concerned that the patient will not comply with the home sampling routine. Rather, physicians should redouble their efforts to get patients to comply". We agree. Yet, the investigators and the Editor continually refer to the traditional six-sample fecal occult blood test (FOBT). A better approach exists and is growing in utility.
Also worrisome concerning colorectal cancer screening is that many physicians perform no screening or rely on sigmoidoscopy or colonoscopy that is performed once every five or ten years, respectively (3). As a result, 56% of patients with colorectal cancer had no procedure within six months of diagnosis (3). The reliance on procedures performed with long intervals is that disease can develop within the time intervals and disease can progress to an advanced stage.
Dr. Marion Nadel et al. surveyed physicians about their practices and found 6.5% of physicians use "other methods" including fecal immunochemical tests (FIT). InSure (Enterix) is a FIT that requires the patient to swish a brush in the toilet water after passage of stool on only two occasions. There is no handling of fecal materials and no dietary or drug restrictions in contrast to traditional FOBTs. Patient compliance with FIT increased 66% compared to traditional FOBT (4). Insure is FDA cleared, included in the American Cancer Society screening guidelines (5), and covered by CMS. We suggest that physicians not already offering FIT to consider an easier approach to colorectal cancer screening associated with higher patient compliance.
Harvey Kaufman, MD firstname.lastname@example.org
1. Collins JF, Lieberman DA, Durbin TE, Weiss DG. Accuracy of screening for feval occult blood on a single stool sample obtained by digital rectal examination: a comparison with recommended sampling practice. Ann Intern Med 2005;142:81-85.
2. Nadel MR, Shapiro JA, Klabunde CN, Seef LC, et al. A national survey of primary care physicians' methods for screening for fecal occult blood. Ann Intern Med 2005;142:86-94.
3. Cooper GS. Payes JD. Receipt of colorectal testing prior to colorectal cancer diagnosis. Cancer 2005;103:1-6.
4. Young GP, St John DJB, Cole SR, Bielecki BE, Pizzey C, et al. Prescreening evaluation of a brush-based faecal immunochemical test for haemoglobin. J Med Screen 2003;10:123-28.
5. Smith RA, Cokkinides V, Eyre HJ. American Cancer Society guidelines for the early detection of cancer, 2003. CA-A Cancer J for Clinicians. 2003:53:27-43.
Harold C Sox
April 29, 2005
In response to Dr. Wolff and Dr. Hoffer, I can but elaborate on my editorial. One concern is using office guaiac in lieu of other, better tests, which is common practice, according to the survey (1). A second concern is placing too much weight on a negative result on a test that misses 95% of colonic neoplasia. The third concern is inefficient use of invasive follow-up tests. The office guaiac has a likelihood ratio- positive of 1.68 (2), which means that the probability of high-risk neoplasia rises from 7.0% to 12% after a positive test, which means doing 8.5 negative follow-up colonoscopies to for every positive colonoscopy. Using the six sample home test, the probability would rise from 7.0% to 35%, which would require fewer than 3 colonoscopies to detect an important lesion. Ultimately, physicians must develop better office systems to support home testing and identify non-adherent patients.
I am in only partial agreement with Dr. Jackson. Fecal occult blood testing using six samples obtained at home is an important test because, coupled with colonoscopy when positive, it reduces mortality from colon cancer from 8.83 deaths per 1000 over 13 years to 5.88 deaths per 1000 (3). It's not a perfect test. Its sensitivity of 23.5% is very poor, so that it generates many negative colonoscopies. But, it does reduce colon cancer death rates, which is more than you can say for sure about any other colon cancer screening test, least of all the office guaiac. We should advocate home testing, and we should develop office systems to help us raise adherence rates to a test that reduce colon cancer rates substantially.
Is a bad screening test better than none at all? Now there's a good subject for debate!
Harold C. Sox Editor
1. Nadel MR, Shapiro JA, Klabunde CN, Seeff LC, Uhler R, Smith RA, and Ransohoff DF A National Survey of Primary Care Physicians' Methods for Screening for Fecal Occult Blood Ann Intern Med, Jan 2005; 142: 86 - 94.
2. Collins JF, Lieberman DA, Durbin TE, Weiss DG and the Veterans Affairs Cooperative Study #380 Group* Accuracy of Screening for Fecal Occult Blood on a Single Stool Sample Obtained by Digital Rectal Examination: A Comparison with Recommended Sampling Practice Ann Intern Med, Jan 2005; 142: 81 - 85.
3. Mandel JS, Bond JH, Church TR, Snover DC, Bradley GM, Schuman LM, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study. N Engl J Med. 1993;328:1365-71.
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