Role of double-contrast barium enema in colorectal cancer screening based on fecal occult blood

Aims and background: Screening for colorectal cancer by fecal occult-blood testing has been shown to be effective in reducing colorectal cancer mortality. Total colonoscopy is the test of choice for the assessment of fecal occult blood-positive subjects. Double-contrast barium enema is commonly employed to study the rest of the colon when colonoscopy is incomplete. The present study evaluated the contribution of double-contrast barium enema in detecting neoplastic lesions of the colon in fecal occult-blood-positive subjects with incomplete colonoscopy. Methods: In the frame of a screening program for colorectal cancer in the Florence District, a new immunochemical fecal occult-blood test replaced the classic guaiac fecal occult-blood test in 1993. Subjects with a positive fecal occult-blood test were invited to undergo total colonoscopy. Incomplete colonoscopy prompted double-contrast barium enema. Type and rate of neoplastic lesions detected by endoscopy or double-contrast barium enema as single methods or combined were evaluated. Results: A total of 38,829 subjects underwent fecal occult-blood testing in the period 1993-2000. Overall, 1,542 were positive. Assessment was refused by 235 subjects. Out of 1,307 subjects accepting assessment, total colonoscopy was attempted in 1,294: of these, it was not possible in 343 cases, and double-contrast barium enema was advised and performed in 261 subjects. Colorectal cancer was detected in 115 subjects, single or multiple adenomas in 323, hyperplastic polyps in 58, inflammatory, hamartomatous or not histologically confirmed polyps in 38, and other benign non-polypoid findings or no abnormality in 773. There were significant differences between the rates of detected colorectal cancers or adenomas of total and incomplete colonoscopy. There were also significant differences between incomplete colonoscopy and the combination of incomplete colonoscopy and double-contrast barium enema as regards rates of detected colorectal cancer, and between total colonoscopy and the combination of incomplete colonoscopy with double-contrast barium enema as regards rates of detected adenomas. Double-contrast barium enema associated to incomplete colonoscopy was responsible for an increase in detection rates of cancer or adenoma of 2.3%(o) or 3.8%(o), respectively. Conclusions: Double-contrast barium enema was useful in detecting colorectal cancer beyond the range reached by incomplete colonoscopy, whereas our data confirmed a lower sensitivity of double-contrast barium enema for polyps. The diagnostic contribution observed in the present survey confirms the opportunity of performing double-contrast barium enema as a routine adjunct to incomplete colonoscopy. Nevertheless, in order to maximize the detection rate of adenomas, the rate of total colonoscopy should be kept as high as possible.