Colonoscopy best for polypoid lesions: vs. barium enema, colonography.
"All three tests are probably acceptable if detecting cancer is the goal, [but] air contrast barium enema may not be justifiable for use in patients in whom the only objective is to identify polypoid lesions," Dr. Don C. Rockey said at the annual Digestive Disease Week.
In a study funded by the National Cancer Institute, Dr. Rockey and his associates compared the specificity and sensitivity of the three imaging tests in 691 patients at 15 medical centers who had an indication for a colon examination, including fecal occult blood, hematochezia, iron deficiency anemia, or a family history of colon cancer.
Study participants first underwent air contrast barium enema (ACBE). A week or two later they underwent computed tomographic colonography (CTC) and optical colonoscopy (OC) on the same day. Preparations for all studies were standard, without stool tagging, and the researchers were blinded to the findings on other tests.
Sensitivity was determined by matching of individual lesions for location and size. "For example, a lesion 10 mm or greater in size identified by colonoscopy would be considered a matching lesion if a lesion 5 mm or greater in size was identified in the same or in an adjacent segment on either imaging test," said Dr. Rockey, who directs the liver center at Duke University Medical Center, Durham, N.C.
The researchers were "highly experienced in ACBE and colonoscopy," he said. Experience with CT colonography varied, but all inexperienced readers had identical training in the procedure before the study began.
The mean age of study participants was 57 and about one-third were female. Of the 691 patients, 63 had 76 lesions 10 mm or greater in size, of which 55 were either adenomas or cancers; 116 had 154 lesions that were 6-9 mm in size, of which 97 were adenomas or cancers.
The per-patient sensitivity for detecting lesions at least 1 cm in size regardless of histology was 48% for ACBE, 59% for CTC, and 98% for OC. Sensitivity was significantly greater for OC than for the other two tests.
The sensitivity for detecting lesions 6-9 mm in size was 35% for ACBE, 51% for CTC, and 99% for OC. Again, sensitivity was significantly greater for OC than for either of the other two tests.
When only adenomas and cancers were considered in the analysis, the sensitivity of ACBE and CTC increased slightly, but overall trends remained the same. The sensitivity for detecting adenomatous and cancerous lesions at least 1 cm in size was 55% for ACBE, 64% for CTC, and 99% for OC. The sensitivity for detecting adenomatous and cancerous lesions 6-9 mm in size was 31% for ACBE, 60% for CTC, and 100% for OC. "It should be noted that differences between barium enema and CTC were slightly more pronounced in the 6-to 9-mm lesion category," Dr. Rockey said.
Meanwhile, the specificity for detecting lesions at least 1 cm in size regardless of histology was 90% for ACBE, 96% for CTC, and 100% for OC. The specificity for detecting lesions 6-9 mm in size was 82% for ACBE, 89% for CTC, and 100% for OC.
After undergoing all three procedures, patients were asked to rate each test. "Patients felt there was no real difference in the difficulty of the preparations, or with regard to respect or a loss of dignity during any of the procedures," Dr. Rockey noted. "However, subjects felt that ACBE was the most uncomfortable test and that colonoscopy was the most comfortable. Additionally, patients were most willing to repeat colonoscopy."
He pointed out that CTC is a "rapidly moving field" and that more studies of its efficacy are underway.
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|Title Annotation:||Clinical Rounds|
|Publication:||Family Practice News|
|Date:||Jun 15, 2004|
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