Fecal Occult Blood Testing for Colorectal Cancer Screening: Use the Finger
Fecal Occult Blood Testing for Colorectal Cancer Screening: Use the Finger
Abstract & Commentary
Synopsis: Fecal occult blood testing (FOBT) using a specimen obtained at digital rectal examination has the same positive predictive value as occult blood testing on spontaneous passed stools (SPS).
Source: Burke CA, et al. Am J Gastroenterol. 2002;96:3175-3177.
Digital rectal examination should be done as part of routine physical examinations, and occult blood testing of the specimen from the examining glove is desirable and useful for identifying patients at increased risk of colorectal neoplasia.
It has been recommended that all patients over age 50 should have FOBT annually, but this is actually accomplished in a small minority of cases. Part of the explanation for this involves guidelines for FOBT that mandate occult blood testing on 3 spontaneously passed stools, a prior specialized and restrictive diet, and avoidance of NSAIDs. In the past, physicians often performed occult blood testing on fecal specimens obtained from the examining glove at the time of digital rectal examination. However, there was some concern that this technique might result in anal trauma or otherwise increase false-positive occult blood tests. This paper included reviews of records from patients who underwent colonoscopy for positive FOBT results in the Department of Gastroenterology at the Cleveland Clinic Foundation. One hundred sixty-five patients with a mean age of 61 years were examined. Twenty-nine percent of the patients with positive results from SPS testing had colorectal neoplasia, and 33% of those with positive occult blood tests on digital rectal examination had neoplasia. There were no differences in adenomas or invasive carcinomas between the groups.
Comment by Malcolm Robinson, MD, FACP, FACG
Colorectal cancer screening by FOBT is known to reduce mortality from colorectal cancer by 33%, but less than 35% of Americans underwent such screening in the past 5 years. It is estimated that there will be 130,000 colorectal cancer cases this year and 56,000 deaths. Reasons for not testing stools for occult blood are varied, but the inconvenience of testing SPS certainly plays a role. Another large study confirmed that stool testing for occult blood from rectal exam vs. SPS did not result in divergent results in terms of colonic neoplasia (49.4% vs 44.3%).1 Since many patients are seen in physicians’ offices for routine examinations, and since rectal examination is easily done in that setting, a strong argument can be made for the widespread use of FOBT on finger-obtained stool specimens. This should result in significant decrements in colorectal cancer incidence, morbidity, and mortality.
Reference
1. Bini EJ, et al. Arch Intern Med. 1999;159:2022-2026.
Dr. Robinson, Medical Director, Oklahoma Foundation for Digestive Research; Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City, OK, is Associate Editor of Internal Medicine Alert.
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