Screening for colorectal neoplasia in asymptomatic patients using flexible fiberoptic sigmoidoscopy

Four hundred seventeen asymptomatic patients with an average age of 52 years underwent screening flexible fiberoptic sigmoidoscopy. Seventy-three polyps were detected in 52 patients with a 17.5 per cent detection rate. Half were above 25 cm and one-third were greater than 1.0 cm in size. Biannual follow-up of these patients is planned to determine the efficacy of this screening procedure combined with removal of all polyps in preventing the development of colorectal cancer.     

Screening and surveillance for colorectal neoplasia: uncertainties of colonoscopic management

Over the past decade the use of screening and surveillance modalities has been associated with a small but significant decrease in the incidence of colorectal cancer and an increase in curability of lesions that are found. Although consensus-based international guidelines have stressed the variety of possible diagnostic options that can serve this purpose, in many countries colonoscopy withremoval of all polyps has become the test of choice. The evidence-base for this choice is largely derivative rather than direct and prospective, and many uncertainties remain in its use as a primary screening modality. This review examines our current guidelines relative to risk stratifying the populations offered the test; the onset, interval, and discontinuation of testing; and the important role of operator variability in outcome.     

Screening for colorectal cancer with immunochemical faecal occult blood tests

Population-based studies have shown that guaiac faecal occult blood testing followed by colonoscopy in case of positivity can reduce colorectal cancer mortality. However these tests have been criticised for their fairly low sensitivity. For this reason attention has been given to alternative tests. The aim of this paper is to review the evidence for screening for colorectal cancer using qualitative immunochemical faecal occult blood tests. For the complete range of tested cut-off values, immunochemical faecal occult blood tests lead to higher diagnostic yield, improved sensitivity and greater participation. The optimal number of samples and the optimal cut-off value has to suit local resources and the acceptability of missed cancers. All economic evaluations, despite some differences between studies, add further arguments to support the opinion that the immunochemical faecal occult blood test is currently the most cost-effective screening test for average-risk populations. These economic evaluations provide strong arguments in favour of the 1-sample strategy. With decreasing the cut-off value similar performances can be achieved with one-compared to two day sampling. Too few data are currently available to accurately compare existing qualitative tests.     

Screening for colorectal neoplasms

Testing for occult blood in stool is used frequently as a screening technique for colorectal carcinomas, but no study has ever shown an improved survival rate for colorectal carcinoma in patients screened by this method. Consequently, the authors have prospectively compared the sensitivity of endoscopy and occult blood testing in finding colorectal neoplasms. During the first year of the Surgical Endoscopy Service, 585 patients underwent sigmoidoscopy or colonoscopy. Seventy-nine patients (13.5 percent) were excluded from the study because their occult blood status was not recorded. Patients averaged 63+10 years of age and 98 percent were men. Of the 348 patients with occult blood negative stools 55.5 percent underwent colonoscopy and 44.5 percent underwent sigmoidoscopy. Polyps were found in 25.6 percent of these patients, colorectal carcinomas in 2.6 percent, and diverticulosis 36.2 percent. Of the 158 patients with occult blood positive stool, 76.5 percent underwent colonoscopy and 23.4 percent underwent sigmoidoscopy. Polyps were discovered in 39.0 percent of these patients, colorectal carcinomas in 10.1 percent, and diverticulosis in 43.0 percent. Thus, the occult blood test was negative in 59 percent of patients with polyps and 36 percent with colorectal cancers. These data indicate that lower gastrointestinal endoscopy is superior to occult blood testing in detecting colorectal neoplasms. These results further suggest that using the occult blood test as a screening test for colorectal neoplasms will result in a significant number of these lesions being missed at an early curable stage. Read at the meeting of The American Society of Colon and Rectal Surgeons, Houston, Texas, May 11 to 15, 1986.     

Screening for colorectal cancer

PURPOSE: Screening for colorectal cancer using a guaiac-based fecal occult blood, or Hemoccult®, test has been demonstrated to reduce colorectal cancer mortality. However, the magnitude of effectiveness is relatively low because of poor sensitivity of the Hemoccult® test. The immunochemical fecal occult blood test has been shown to be much more sensitive than the Hemoccult® test in detecting preclinical colorectal cancer in an asymptomatic population. The purpose of this article is to discuss the validity of the immunochemical fecal occult blood test and the efficacy of a population-based screening program using the test. METHODS: Relevant articles were primarily identified through MEDLINE search. Review was focused on the studies of population screening programs with the immunochemical fecal occult blood test. RESULTS: Sensitivities for colorectal cancer calculated in the same population were reported to be 67 to 89 percent and only 33 to 37 percent for the immunochemical test and Hemoccult® test, respectively. Case-control studies and other observational studies showed that screening programs using the immunochemical fecal occult blood test by hemagglutination reaction would reduce the risk of dying of colorectal cancer by 60 percent or more for those screened annually compared with those unscreened. It was also shown that a screening strategy using the immunochemical fecal occult blood test had the best cost-effectiveness ratio among the methods available. Nearly 5 million persons are currently screened per year in Japan, yielding 0.15 to 0.2 percent colorectal cancer cases among persons with positive fecal occult blood test results. CONCLUSIONS: These results strongly suggest that a screening program with immunochemical fecal occult blood test has promising advantages in terms of effectiveness over programs with the Hemocult® test. More stress is warranted on introduction of immunochemical fecal occult blood testing as a screening test in place of the guaiac fecal occult blood test.     

Screening for colorectal cancer

A review of the literature regarding the screening strategies for colorectal cancer (CRC), particularly for average risk individuals, is analysed. The advantages and disadvantages or limitations of screening modalities for CRC, such as faecal occult blood testing (FOBT) with guaiac-based tests or the new faecal deoxyribonucleic acid tests, endoscopic screening by flexible sigmoidoscopy, colonoscopy, or CT-colonography and double contrast barium enema examination, are reported. The efficacy and cost of the screening tests are evaluated, and it is found that any of the suggested tests is more cost effective than other medical intervention or treatment as compared with no screening. The reported compliance to any form of screening test was 30-40%, a rate that is low enough. The experience of our surgical department of a screening programme, based on FOBT, on 4189 individuals over 50 years old, and application of colonoscopy in positive subjects, is reported.     

Screening for colorectal cancer

Screening for a disease is an important concept in modern day preventive medicine. The aim is early disease detection and treatment of both asymptomatic individuals and those at risk of the disease, with the goal of better survival. The WHO published a set of essential criteria for screening in 1968 and colorectal cancer has been identified as a candidate disease. Three methods of screening are evaluated here: fecal occult blood test, flexible sigmoidoscopy and colonoscopy. Newer techniques are still being studied and preliminary results are encouraging. The incidence of colorectal cancer in Asia has been increasing in association with changes in lifestyle and therefore, designing efficient, acceptable screening programs for these populations is an important issue in the prevention of this common malignant disease.     

Screening for colorectal cancer

Although there are several methods available for colon cancer screening, none is optimal. This article reviews methods for screening, including fecal occult blood tests, flexible sigmoidoscopy, colonoscopy, CT colonography, capsule endoscopy, and double contrast barium enema. A simple, inexpensive, noninvasive, and relatively sensitive screening test is needed to identify people at risk for developing advanced adenomas or colorectal cancer who would benefit from colonoscopy. It is hoped that new markers will be identified that perform better. Until then we fortunately have a variety of screening strategies that do work.     

Comparison of three faecal occult blood tests in the detection of colorectal neoplasia.

METHODS AND AIMS: For the detection of colorectal neoplasia, 192 consecutive patients had colonoscopy to evaluate the sensitivity and specificity of three faecal occult blood tests (FOBT). Of 160 evaluable patients (96 female, mean age 51.9), 21 patients (13.1%) had adenomas and three patients (1.9%) had colorectal carcinoma. RESULTS: When comparing all three faecal occult blood tests for the detection of colorectal neoplasia, the sensitivity of Monohaem (43.8%) was superior to both Hemoccult II (25%) and to BM-Test colon albumin (25%). The specificity of Monohaem (94.6%) was greater than both Hemoccult II (88%) and BM-Test colon albumin (89%). Using McNemar's test, Monohaem was a more accurate FOBT than Hemoccult II and BM-Test albumin (p < 0.05). In the 21 patients with adenomatous polyps, FOBT sensitivity seemed to be dependent on polyp size, but not polyp site. CONCLUSIONS: Monohaem, a feacal occult blood test that uses a monoclonal antibody that is specific for human haemoglobin, is a more accurate test in the detection of colorectal neoplasia and should possibly be used in colorectal cancer screening programmes.