Faecal occult blood testing and colonoscopy in the surveillance of subjects at high risk of colorectal neoplasia

Abstract

Colonoscopy is the established method of surveillance of subjects at high risk of developing colorectal neoplasia but the procedure is expensive, time consuming and occasionally hazardous. Faecal occult blood tests can be prepared at home and are cheap, simple and safe. Hemeselect is an immunological faecal occult blood test that is more sensitive for colorectal cancer than Haemoccult. The aim of this study was to determine the sensitivity of the Hemeselect test for asymptomatic colorectal neoplasia in subjects at high risk of the disease who were undergoing colonoscopy, thus assessing its suitability as an alternative means of screening high-risk groups. A total of 919 asymptomatic subjects were asked to complete Hemeselect tests. These were completed satisfactorily by 808 individuals (compliance rate 88 per cent) and were positive in 164 patients (20 per cent). At colonoscopy 11 cancers were detected in ten patients (seven Hemeselect positive) and 36 (16 Hemeselect positive) had at least one adenoma 1 cm or more in diameter. The test sensitivites of Hemeselect for carcinoma and large (1 cm or more) adenomas were 70 and 44 per cent respectively. In a subset of 417 subjects who also completed Haemoccult tests, the sensitivities were 33 and 18 per cent. Hemeselect specificity is 88 per cent compared with 98 per cent for Haemoccult. While the sensitivity of Hemeselect is higher than that of Haemoccult, it is still insufficient to replace colonoscopy in high-risk groups.

Faecal calprotectin levels in a high risk population for colorectal neoplasia

“…A recent study14 involving a similarly high risk group as the present study demonstrated a positivity rate of 20% for HemeSELECT in 808 individuals; sensitivity for CRC and adenomas ⩾1 cm was 70% and 44%, respectively, values similar to those obtained for calprotectin. A subset of 417 of the 808 persons also completed Hemoccult-II tests with sensitivities of 33% and 18%.…”

Comparison of a peanut agglutinin test and an immunochemical faecal occult blood test in detecting colorectal neoplasia in symptomatic patients

“…A detection rate of 45% -81% has been reported for symptomatic cancers [21]. Immunological tests, specific for human haemoglobin, have been shown to be more sensitive for symptomatic colorectal cancer than guaiac-based tests [21,22] and there is some evidence to show that they are more sensitive as a screening method for the asymptomatic population as well [20]. However, the improvement in sensitivity is reached at the expense of specificity.…”

Effect of Verification Bias on the Sensitivity of Fecal Occult Blood Testing: a Meta-Analysis

“…The studies that attempted to reduce verification bias are listed in Table 2. [51][52][53][54][55][56][57][58][59][60] These 10 studies included 185 subjects with colorectal cancer and 31,804 controls. Seven studies reduced verification bias by performing colonoscopy on all of the potential subjects 51,54-56,58-60 while 3 studies used longitudinal follow-up for at least 2 years.…”