The yield of flexible sigmoidoscopy and double-contrast barium enema in the diagnosis of neoplasms in the large bowel in patients with a positive Hemoccult test.

BACKGROUND AND STUDY AIMS: In an ongoing screening study of 68,306 patients for early detection of colorectal cancer, those with a positive Hemoccult II test (H2) were examined with a flexible sigmoidoscope (60 cm) (FS) and double-contrast barium enema (DCE). The aim of this study was to compare the results of FS and DCE examinations in the rectum and the sigmoid colon, and to evaluate the benefit of DCEs. PATIENTS AND METHODS: 1831 FS and DCE examinations were performed on the basis of positive H2 tests (90% acceptance rate for positive Hemoccult tests). The radiologists were unaware of the endoscopic findings. One hundred and thirty-five patients underwent total colonoscopy due to abnormalities found on FS or DCE, or both. All patients were followed-up through various Swedish cancer registers (range: 50-145 months). RESULTS: The sigmoidoscope was fully introduced in 71% of cases, and the mean time for the examination was 5 minutes. The combination of FS and DCE detected 235 adenomas of 1 cm and more, and 81 cancers which were in Dukes stages A (n = 29), B (n = 22), and C (n = 23). Twenty-one cancers (26%) and 24 adenomas (10%) identified on DCE were above the rectosigmoid area. The rate of overlooked adenomas (> or = 1.0 cm) and cancers was 22 and five for FS in the rectosigmoid area, and 55 and 15, respectively, for DCE. Adenomas found in the rectosigmoid area were only rarely associated with more proximal adenomas of 1 cm and more (1%). CONCLUSIONS: This approach-screening by FS and DCE, and selective use of colonoscopy in case of abnormalities-leads to the diagnosis of significant colonic tumors (larger adenomas and cancers) in 17.7% of cases; only two of eighty-three cancers (2.4%) were overlooked with this method.

Value of retesting subjects with a positive Hemoccult in screening for colorectal cancer.

Within a prospective randomized screening study for early detection of colorectal cancer with rehydrated Hemoccult II test, the possibility of increasing the specificity of the test by retesting patients with an initially positive Hemoccult II test was investigated. Of those offered the test 3561 (62.6 per cent) returned it and it was positive in 210 cases (5.9 per cent). The repeat test was performed by 184 patients and was positive in 68 (1.9 per cent). All those with a positive initial test had rectosigmoidoscopy to 60 cm and a double contrast enema. A carcinoma was found in one in seven patients with a positive retest but in only one in 100 patients with a negative retest (P less than 0.001). The specificity of the test was, therefore, increased from 95 per cent to 98 per cent and the sensitivity was unchanged. Rescreening was offered at a later date and increased numbers were available: 7147 patients returned the test and 369 (5.2 per cent) were positive. The test was repeated in 360 patients and 118 (1.7 per cent) were positive. A colorectal neoplasm was found in one in three of those with a positive repeat test, compared with one in seven of those with a negative repeat test. In conclusion, screening for early detection of colorectal cancer with a rehydrated Hemoccult II test may be followed by investigation of only those patients with a positive retest. Such a procedure will reduce the work-load by 60 per cent without reducing sensitivity.