A quantitative immunochemical faecal occult blood test is more efficient for detecting significant colorectal neoplasia than a sensitive guaiac test

Risk of gastrointestinal cancer in a symptomatic cohort after a complete colonoscopy: Role of faecal immunochemical test

BACKGROUND

Faecal immunochemical test (FIT) has been recommended to assess symptomatic patients for colorectal cancer (CRC) detection. Nevertheless, some conditions could theoretically favour blood originating in proximal areas of the gastrointestinal tract passing through the colon unmetabolized. A positive FIT result could be related to other gastrointestinal cancers (GIC).

AIM

To assess the risk of GIC detection and related death in FIT-positive symptomatic patients (threshold 10 μg Hb/g faeces) without CRC.

METHODS

Post hoc cohort analysis performed within two prospective diagnostic test studies evaluating the diagnostic accuracy of different FIT analytical systems for CRC and significant colonic lesion detection. Ambulatory patients with gastrointestinal symptoms referred consecutively for colonoscopy from primary and secondary healthcare, underwent a quantitative FIT before undergoing a complete colonoscopy. Patients without CRC were divided into two groups (positive and negative FIT) using the threshold of 10 μg Hb/g of faeces and data from follow-up were retrieved from electronic medical records of the public hospitals involved in the research. We determined the cumulative risk of GIC, CRC and upper GIC. Hazard rate (HR) was calculated adjusted by age, sex and presence of significant colonic lesion.

RESULTS

We included 2709 patients without CRC and a complete baseline colonoscopy, 730 (26.9%) with FIT ≥ 10 µgr Hb/gr. During a mean time of 45.5 ± 20.0 mo, a GIC was detected in 57 (2.1%) patients: An upper GIC in 35 (1.3%) and a CRC in 14 (0.5%). Thirty-six patients (1.3%) died due to GIC: 22 (0.8%) due to an upper GIC and 9 (0.3%) due to CRC. FIT-positive subjects showed a higher CRC risk (HR 3.8, 95%CI: 1.2-11.9) with no differences in GIC (HR 1.5, 95%CI: 0.8-2.7) or upper GIC risk (HR 1.0, 95%CI: 0.5-2.2). Patients with a positive FIT had only an increased risk of CRC-related death (HR 10.8, 95%CI: 2.1-57.1) and GIC-related death (HR 2.2, 95%CI: 1.1-4.3), with no differences in upper GIC-related death (HR 1.4, 95%CI: 0.6-3.3). An upper GIC was detected in 22 (0.8%) patients during the first year. Two variables were independently associated: anaemia (OR 5.6, 95%CI: 2.2-13.9) and age ≥ 70 years (OR 2.7, 95%CI: 1.1-7.0).

CONCLUSION

Symptomatic patients without CRC have a moderate risk increase in upper GIC, regardless of the FIT result. Patients with a positive FIT have an increased risk of post-colonoscopy CRC.

Stool Investigations for Colorectal Cancer Screening: From Occult Blood Test to DNA Analysis

PURPOSE

We report an update of current methods for colorectal cancer (CRC) screening based on fecal sample analysis.

METHODS

A systematic review of the literature was performed in MEDLINE, EMBASE, and Science Direct electronic databases.

RESULTS

Blood in the stools is the first and most used strategy. Fecal occult blood test (FOBT) and fecal immunochemical test (FIT) are the main methods. Both are economic, easy to perform with high specificity, and low sensitivity. Based on CRC multi-step process with genetic and epigenetic alterations in large bowel cell DNA, single mutations or panels of alterations have been detected. These tests have the advantage of a marked improvement of the sensitivity when compared to fecal blood. However, high costs, poor availability, and correct choice of marker panel represent the major limits. A specific sDNA panel including aberrantly methylated BMP3 and NDRG4 promoter regions, mutant k-ras and β-actin (a reference gene for human DNA quantity), and an immunochemical assay for human hemoglobin has been recently approved by Food and Drug Administration. Novel promising biomarkers for CRC screening are represented by microRNAs (miRNAs), a group of 18-25 nucleotide non-coding RNA molecules that regulate gene expression. Reports on these fecal biomarkers are case-control studies, and each of them evaluates single miRNAs or multi-target panels. On the other hand, some fecal proteins have been studied as possible CRC screening markers, even though they demonstrated poor results. Finally, alterations of estrogen receptor-beta (i.e., dramatic reduction in the early stage of CRC) have been demonstrated in tissue samples.

CONCLUSIONS

Specific investigations are warranted in order to add further noninvasive markers to the panel of CRC screening tools.

Colorectal cancer screening: tests, strategies, and perspectives

Screening has a central role in colorectal cancer (CRC) control. Different screening tests are effective in reducing CRC-specific mortality. Influence on cancer incidence depends on test sensitivity for pre-malignant lesions, ranging from almost no influence for guaiac-based fecal occult blood testing (gFOBT) to an estimated reduction of 66–90% for colonoscopy. Screening tests detect lesions indirectly in the stool [gFOBT, fecal immunochemical testing (FIT), and fecal DNA] or directly by colonic inspection [flexible sigmoidoscopy, colonoscopy, CT colonography (CTC), and capsule endoscopy]. CRC screening is cost-effective compared to no screening but no screening strategy is clearly better than the others. Stool tests are the most widely used in worldwide screening interventions. FIT will soon replace gFOBT. The use of colonoscopy as a screening test is increasing and this strategy has superseded all alternatives in the US and Germany. Despite its undisputed importance, CRC screening is under-used and participation rarely reaches 70% of target population. Strategies to increase participation include ensuring recommendation by physicians, introducing organized screening and developing new, more acceptable tests. Available evidence for DNA fecal testing, CTC, and capsule endoscopy is reviewed.

Comparison of fecal occult blood tests for colorectal cancer screening in an Alaska Native population with high prevalence of Helicobacter pylori infection, 2008-2012

Introduction

Alaska Native colorectal cancer (CRC) incidence and mortality rates are the highest of any ethnic/racial group in the United States. CRC screening using guaiac-based fecal occult blood tests (gFOBT) are not recommended for Alaska Native people because of false-positive results associated with a high prevalence of Helicobacter pylori-associated hemorrhagic gastritis. This study evaluated whether the newer immunochemical FOBT (iFOBT) resulted in a lower false-positive rate and higher specificity for detecting advanced colorectal neoplasia than gFOBT in a population with elevated prevalence of H. pylori infection.

Methods

We used a population-based sample of 304 asymptomatic Alaska Native adults aged 40 years or older undergoing screening or surveillance colonoscopy (April 2008–January 2012).

Results

Specificity differed significantly (P < .001) between gFOBT (76%; 95% CI, 71%–81%) and iFOBT (92%; 95% CI, 89%–96%). Among H. pylori-positive participants (54%), specificity of iFOBT was even higher (93% vs 69%). Overall, sensitivity did not differ significantly (P = .73) between gFOBT (29%) and iFOBT (36%). Positive predictive value was 11% for gFOBT and 32% for iFOBT.

Conclusion

The iFOBT had a significantly higher specificity than gFOBT, especially in participants with current H. pylori infection. The iFOBT represents a potential strategy for expanding CRC screening among Alaska Native and other populations with elevated prevalence of H. pylori, especially where access to screening endoscopy is limited.

Population screening for colorectal cancer means getting FIT: the past, present, and future of colorectal cancer screening using the fecal immunochemical test for hemoglobin (FIT)

Fecal immunochemical tests for hemoglobin (FIT) are changing the manner in which colorectal cancer (CRC) is screened. Although these tests are being performed worldwide, why is this test different from its predecessors? What evidence supports its adoption? How can this evidence best be used? This review addresses these questions and provides an understanding of FIT theory and practices to expedite international efforts to implement the use of FIT in CRC screening.

Superior diagnostic performance of faecal immunochemical tests for haemoglobin in a head-to-head comparison with guaiac based faecal occult blood test among 2235 participants of screening colonoscopy

There is increasing evidence that faecal immunochemical tests (FITs) for haemoglobin offer a number of advantages over traditional guaiac based faecal occult blood tests (gFOBTs). However, evidence on diagnostic performance from direct comparisons with colonoscopy findings in all participants in the average risk population is still sparse. We aimed for a head-to-head comparison of three quantitative FITs with a gFOBT among participants of the German screening colonoscopy programme. Pre-colonoscopy stool samples and colonoscopy reports were obtained from 2235 participants of screening colonoscopy in 2005-2009. To enhance comparability of diagnostic performance of the various tests, we assessed sensitivity, specificity, predictive values and likelihood ratios of FITs after adjusting the FIT cut-off haemoglobin (Hb) concentrations in such a way that FIT positivity rates equalled the positivity rate of the gFOBT. Colorectal cancer, advanced adenomas and other adenomas were found in 15 (0.7%), 207 (9.3%) and 398 (17.8%) participants. The gFOBT was positive in 111 (5.0%) participants, with sensitivities (specificities) for detecting colorectal cancer, any advanced neoplasm or any neoplasm of 33.3% (95.2%), 8.6% (95.4%) and 5.5% (95.2%). At the same positivity rate, all three FITs outperformed the gFOBT in all indicators. In particular, all sensitivities of FITs were approximately two to three times higher at increased levels of specificity. All differences were statistically significant, except for some of the performance indicators for colorectal cancer. In conclusion, FITs can detect much larger proportions of colorectal neoplasms even if their cut-offs are set to levels that ensure equally low positivity rates as gFOBT.

Application of the fecal microRNA test to the residuum from the fecal occult blood test

OBJECTIVE

Though the fecal occult blood test is used for colorectal cancer screening worldwide, it does not have a particularly high sensitivity for detecting colorectal cancer. Here we investigated the applicability of the fecal microRNA test to fecal samples that had been used for a previous fecal occult blood test and stored under various conditions.

METHODS

Five colorectal cancer patients and five healthy volunteers were enrolled. Fecal samples were stored for 0-5 days at 4°C, room temperature or 37°C. Total RNA was extracted from the fecal occult blood test residuum and microRNA expression was analyzed by real-time reverse transcription polymerase chain reaction.

RESULTS

There were no remarkable differences either in colorectal cancer patients or in controls with regard to the concentration of RNA extracted from the fecal occult blood test residuum in any of the storage groups compared with the samples prepared on day 0 (Group 0). Ribosomal RNA stored at room temperature or 37°C degraded rapidly. In contrast, the ribosomal RNA stored at 4°C remained intact for at least 5 days. The microRNAs in samples stored at 4°C and room temperature were conserved; however, the microRNAs stored at 37°C were significantly degraded compared with Group 0 (P < 0.05). In the residuum stored at 4°C up to 5 days, the relative quantification of miR-106a normalized with miR-24 in colorectal cancer patients was significantly higher than those in healthy volunteers (P < 0.05). In contrast, the quantification of normalized miR-106a was remarkably low in samples stored at room temperature and 37°C.

CONCLUSIONS

Fecal microRNA of sufficient quality for reverse transcription polymerase chain reaction analysis was extracted from the fecal occult blood test residuum stored at 4°C for up to 5 days.

Current status of screening for colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality. A well-defined precursor lesion (adenoma) and a long preclinical course make CRC a candidate for screening. This paper reviews the current evidence for the most important tests that are widely used or under development for population-based screening.

MATERIAL AND METHODS

In this narrative review, we scrutinized all papers we have been aware of, and carried out searches in PubMed and Cochrane library for relevant literature.

RESULTS

Two screening methods have been shown to reduce CRC mortality in randomised trials: repetitive faecal occult blood testing (FOBT) reduces CRC mortality by 16%; once-only flexible sigmoidoscopy (FS) by 28%. FS screening also reduces CRC incidence (by 18%), FOBT does not. Colonoscopy screening has a potentially larger effect on CRC incidence and mortality, but randomised trials are lacking. New screening methods are on the horizon but need to be tested in large clinical trials before implementation in population screening.

CONCLUSIONS

FS screening reduces CRC incidence and CRC mortality by removal of adenomas; FOBT reduces CRC mortality by early detection of cancer. Several other tests are available, but none has been evaluated in randomised trials. Screening strategies differ considerably across countries.

Faecal immunochemical test accuracy in patients referred for surveillance colonoscopy: a multi-centre cohort study

BACKGROUND

Given the increasing burden on colonoscopy capacity, it has been suggested that faecal immunochemical test (FIT) results could guide surveillance colonoscopy intervals. Against this background, we have evaluated the test accuracy of single and double FIT sampling to detect colorectal cancer (CRC) and/or advanced adenomas in an asymptomatic colonoscopy-controlled high-risk population.

METHODS

Cohort study of asymptomatic high-risk patients (personal history of adenomas/CRC or family history of CRC), who provided one or two FITs before elective colonoscopy. Test accuracy of FIT for detection of CRC and advanced adenomas was determined (cut-off level 50 ng/ml).

RESULTS

1,041 patients provided a FIT (516 personal history of adenomas, 172 personal history of CRC and 353 family history of CRC). Five CRCs (0.5%) and 101 advanced adenomas (9.7%) were detected by colonoscopy. Single FIT sampling resulted in a sensitivity, specificity, PPV and NPV for CRC of 80%, 89%, 3% and 99.9%, respectively, and for advanced adenoma of 28%, 91%, 24% and 92%, respectively. Double FIT sampling did not result in a significantly higher sensitivity for advanced neoplasia. Simulation of multiple screening rounds indicated that sensitivity of FIT for advanced adenoma could reach 81% after 5 screening rounds.

CONCLUSIONS

In once-only FIT sampling before surveillance colonoscopy, 70% of advanced neoplasia were missed. A simulation approach indicates that multiple screening rounds may be more promising in detecting advanced neoplasia and could potentially alleviate endoscopic burden.

Test performance of faecal occult blood testing for the detection of bowel cancer in people with chronic kidney disease (DETECT) protocol

Background

Cancer is a major cause of mortality and morbidity in patients with chronic kidney disease (CKD). In patients without kidney disease, screening is a major strategy for reducing the risk of cancer and improving the health outcomes for those who developed cancers by detecting treatable cancers at an early stage. Among those with CKD, the effectiveness, the efficacy and patients' preferences for cancer screening are unknown.

Methods/Design

This work describes the protocol for the DETECT study examining the effectiveness, efficiency and patient's perspectives of colorectal cancer screening using immunochemical faecal occult blood testing (iFOBT) for people with CKD. The aims of the DETECT study are 1) to determine the test performance characteristics of iFOBT screening in individuals with CKD, 2) to estimate the incremental costs and health benefits of iFOBT screening in CKD compared to no screening and 3) to elicit patients' perspective for colorectal cancer screening in the CKD population. Three different study designs will be used to explore the uncertainties surrounding colorectal cancer screening in CKD. A diagnostic test accuracy study of iFOBT screening will be conducted across all stages of CKD in patients ages 35-70. Using individually collected direct healthcare costs and outcomes from the diagnostic test accuracy study, cost-utility and cost-effective analyses will be performed to estimate the costs and health benefits of iFOBT screening in CKD. Qualitative in-depth interviews will be undertaken in a subset of participants from the diagnostic test accuracy study to investigate the perspectives, experiences, attitudes and beliefs about colorectal cancer screening among individuals with CKD.

Discussion

The DETECT study will target the three major unknowns about early cancer detection in CKD. Findings from our study will provide accurate and definitive estimates of screening efficacy and efficiency for colorectal cancer, and will allow better service planning and budgeting for early cancer detection in this at-risk population.

The DETECT study is also registered with the Australia New Zealand Clinical Trials Registry ACTRN12611000538943

Organized colorectal cancer screening in integrated health care systems

Colorectal cancer (CRC) is an ideal target for early detection and prevention through screening. Noninvasive screening options are the guaiac fecal occult blood test and the fecal immunochemical test. Organized screening offers the promise of uniformly delivering screening to all members of a population who are eligible and due. Organized screening is defined as an explicit policy with defined age categories, method, and interval for screening in a defined target population with a defined implementation and quality assurance structure, and tracking of cancer in the population. The UK National Health Service; the Ontario, Canada Ministry of Health and Long-Term Care; and the US Veteran's Health Administration have used varied organized approaches to deliver guaiac fecal occult blood test screening to their populations. Kaiser Permanente Northern California began CRC screening in the 1960s, initially using flexible sigmoidoscopy. Implementation of organized fecal immunochemical test outreach was associated with improved Healthcare Effectiveness Data and Information Set CRC screening rates between 2005 and 2010 from 37% to 69% and from 41% to 78% in the commercial and Medicare populations, respectively. Organized fecal immunochemical test screening has been associated with an increase in annually detected CRCs, almost entirely because of increased detection of localized-stage cancers.

A higher detection rate for colorectal cancer and advanced adenomatous polyp for screening with immunochemical fecal occult blood test than guaiac fecal occult blood test, despite lower compliance rate. A prospective, controlled, feasibility study

Immunochemical fecal occult blood test (FIT) is a new colorectal cancer (CRC) screening method already recommended by the American screening guidelines. We aimed to test the feasibility of FIT as compared to guaiac fecal occult blood test (G-FOBT) in a large urban population of Tel Aviv. Average-risk persons, aged 50-75 years, were offered FIT or G-FOBT after randomization according to the socioeconomic status of their clinics. Participants with positive tests underwent colonoscopy. Participants were followed through the Cancer Registry 2 years after the study. Hemoccult SENSA™ and OC-MICRO™ (three samples, 70 ng/ml threshold) were used. FIT was offered to 4,657 persons (Group A) and G-FOBT to 7,880 persons (Group B). Participation rate was 25.9% and 28.8% in Group A and B, respectively (p < 0.001). Positivity rate in Group A and B was 12.7% and 3.9%, respectively (p < 0.001). Cancer found in six (0.49%) and eight (0.35%) patients of Group A and B, respectively (NS). Cancer registry follow-up found missed cancer in five (0.22%) cases of Group B and none in Group A (NS). The sensitivity, specificity, negative and positive predictive value for cancer in Group A and B were 100%, 85.9%, 100%, 3.9% and 61.5%, 96.4%, 99.8%, 9.1%, respectively. There was increased detection of advanced adenomatous polyp (AAP) by FIT, irrespective of age, gender, and socioeconomic status (Per Protocol: odds ratio 2.69, 95% confidence interval 1.6-4.5; Intention to Screen: odds ratio 3.16, 95% confidence interval 1.8-5.4). FIT is feasible in urban, average-risk population, which significantly improved performance for detection of AAP and CRC, despite reduced participation.

A simplified, non-invasive fecal-based DNA integrity assay and iFOBT for colorectal cancer detection

PURPOSE

Neoplasia cells exfoliated from colorectal epithelium have dysfunctional apoptotic mechanisms, thus it is possible to identify high-molecular weight DNA fragments in feces. This prospective single-center study was performed to evaluate the sensitivity and specificity of fecal-based DNA integrity versus immunological fecal occult blood test (iFOBT) and calprotectin for colorectal cancer (CRC) and adenoma detection.

METHODS

Feces were collected from 204 subjects and DNA integrity was quantified by quantitative-denaturing high performance liquid chromatography (QdHPLC). Calprotectin and iFOBT were assessed using commercial kits. The diagnostic performance was calculated by receiver operating characteristic (ROC) curves analysis.

RESULTS

A total of 192 fecal specimens were analyzed and 12 samples were excluded due to DNA degradation. We found long DNA (L-DNA) occurrence in feces with a sensitivity of 86% (n = 24/28) and a specificity of 81% for CRC detection. To minimize false-positive cases of the developed test, area under the curve of ROC was evaluated such that the specificity was increased to 92% with decreased sensitivity to 79%, p = 0.0001 for CRC detection. iFOBT was positive in 51% (n = 14/27) while calprotectin was positive in 75% (n = 18/27). The combination of iFOBT and L-DNA identified a greater number of CRC cases with a sensitivity of 89% and a specificity of 95%, p < 0.001. The combination also improved the sensitivity of polyps, particularly high-grade dysplasia and advanced adenoma (33%, p = 0.0015) as opposed to a single evaluation assay (17-21%).

CONCLUSIONS

This study illustrates the usefulness of fecal DNA integrity assay by QdHPLC as a non-invasive, easy-to-perform, and reproducible method with a high level of sensitivity in detecting individuals with colorectal neoplasia. Combination of iFOBT and L-DNA improves the sensitivity for CRC and adenoma detection.

A simplified, non-invasive fecal-based DNA integrity assay and iFOBT for colorectal cancer detection

PURPOSE

Neoplasia cells exfoliated from colorectal epithelium have dysfunctional apoptotic mechanisms, thus it is possible to identify high-molecular weight DNA fragments in feces. This prospective single-center study was performed to evaluate the sensitivity and specificity of fecal-based DNA integrity versus immunological fecal occult blood test (iFOBT) and calprotectin for colorectal cancer (CRC) and adenoma detection.

METHODS

Feces were collected from 204 subjects and DNA integrity was quantified by quantitative-denaturing high performance liquid chromatography (QdHPLC). Calprotectin and iFOBT were assessed using commercial kits. The diagnostic performance was calculated by receiver operating characteristic (ROC) curves analysis.

RESULTS

A total of 192 fecal specimens were analyzed and 12 samples were excluded due to DNA degradation. We found long DNA (L-DNA) occurrence in feces with a sensitivity of 86% (n = 24/28) and a specificity of 81% for CRC detection. To minimize false-positive cases of the developed test, area under the curve of ROC was evaluated such that the specificity was increased to 92% with decreased sensitivity to 79%, p = 0.0001 for CRC detection. iFOBT was positive in 51% (n = 14/27) while calprotectin was positive in 75% (n = 18/27). The combination of iFOBT and L-DNA identified a greater number of CRC cases with a sensitivity of 89% and a specificity of 95%, p < 0.001. The combination also improved the sensitivity of polyps, particularly high-grade dysplasia and advanced adenoma (33%, p = 0.0015) as opposed to a single evaluation assay (17-21%).

CONCLUSIONS

This study illustrates the usefulness of fecal DNA integrity assay by QdHPLC as a non-invasive, easy-to-perform, and reproducible method with a high level of sensitivity in detecting individuals with colorectal neoplasia. Combination of iFOBT and L-DNA improves the sensitivity for CRC and adenoma detection.

Effectiveness of the immunofecal occult blood test for colorectal cancer screening in a large population

BACKGROUND

Guaiac tests are the most widely used tests to detect colorectal cancer (CRC). However, their sensitivity is relatively low and results may be affected by various factors. Immunofecal occult blood test (IFOBT) is specific for human hemoglobin and does not require dietary restrictions.

AIMS

The aim of this study was to evaluate the effectiveness of IFOBT for the screening of precancerous lesions and CRC.

METHODS

From July 2006 to June 2007, IFOBT was performed on 5,919 adults who received periodic health examinations in our hospital. The positive cases were examined by colonoscopy and a double-contrast barium enema. Diagnosis was confirmed by histopathological analysis.

RESULTS

Positive IFOBT was detected in 314 of 5,919 cases (5.30%). Further examinations were made in 264 IFOBT-positive cases. Of these, 116 cases with colorectal cancer (16 cases) or precancerous lesions (94 cases with colorectal adenomatous polyps and 6 cases with active ulcerative colitis) were detected. The total detection rate of CRC and precancerous lesions was 43.94% (116/264). TNM classification of 16 CRC cases was as follows: TNM I in eight cases (50.00%), TNM II in seven cases (43.75%) and TNM III in one case (6.25%), indicating IFOBT can detect CRC in the early stages.

CONCLUSION

Regular IFOBT can detect precancerous lesions and CRC in early stages and can thus reduce mortality from CRC.

Use of faecal markers in screening for colorectal neoplasia: a European group on tumor markers position paper

Several randomized controlled trials have shown that population-based screening using faecal occult blood testing (FOBT) can reduce mortality from colorectal neoplasia. Based on this evidence, a number of countries have introduced screening for colorectal cancer (CRC) and high-risk adenoma and many others are considering its introduction. The aim of this article is to critically review the current status of faecal markers as population-based screening tests for these neoplasia. Most of the available faecal tests involve the measurement of either occult blood or a panel of DNA markers. Occult blood may be measured using either the guaiac faecal occult blood test (gFOBT) or a faecal immunochemical test (iFOBT). Although iFOBT may require a greater initial investment, they have several advantages over gFOBT, including greater analytical sensitivity and specificity. Their use results in improved clinical performance and higher uptake rates. Importantly for population screening, some of the iFOBTs can be automated and provide an adjustable cutoff for faecal haemoglobin concentration. However, samples for iFOBT, may be less stable after collection than for gFOBT. For new centres undertaking FOBT for colorectal neoplasia, the European Group on Tumour Markers recommends use of a quantitative iFOBT with an adjustable cutoff point and high throughput analysis. All participants with positive FOBT results should be offered colonoscopy. The panel recommends further research into increasing the stability of iFOBT and the development of improved and affordable DNA and proteomic-based tests, which reduce current false negative rates, simplify sample transport and enable automated analysis.

Esophago-gastro-duodenoscopy is not indicated in patients with positive immunochemical test and nonexplanatory colonoscopy

OBJECTIVES

Patients with positive fecal occult blood test and unrevealing colonoscopy are often advised to undergo esophago-gastro-duodenoscopy (EGD) to exclude a bleeding source in the upper gastrointestinal tract. In this study, we evaluated EGD findings in patients with positive immunochemical fecal occult blood test (I-FOBT) not explained by colonoscopy.

METHODS

Out of 1221 consecutive patients having total colonoscopy after preparing I-FOBT (OC-MICRO, with threshold of 75 or 100 ngHb/ml), we included only patients without colorectal cancer or advanced adenomatous polyp on colonoscopy, who also underwent EGD within 4 months of the fecal blood testing. Findings on EGD were classified as those lesions which are likely or unlikely to bleed.

RESULTS

EGD was performed in 160 patients after a negative colonoscopy. The procedure was performed 1.6 ± 1.4 months after the I-FOBT. Lesion with a bleeding potential was found in 24 patients (15%). In three (12.5%) and two (8.3%) of these patients I-FOBT was positive at the 75 and 100 ngHb/ml threshold, respectively. In 136 patients EGD was normal, and I-FOBT was similarly positive in 16 (11.7%) and 13 patients (9.5%), respectively. The mean fecal hemoglobin was also similar between the groups.

CONCLUSION

Immunological FOBT positivity was not correlated with the finding of lesions, which are likely to bleed on EGD. Thus, EGD is probably not indicated in patients with positive I-FOBT and unrevealing colonoscopy.

Effect of verification bias on the sensitivity of fecal occult blood testing: a meta-analysis

OBJECTIVES

There is controversy regarding the sensitivity of fecal occult blood tests (FOBT) for detecting colorectal cancer. Many of the published studies failed to correct for verification bias which may have increased the sensitivity.

METHODS

A meta-analysis of published studies evaluating the sensitivity and specificity of chemical-based FOBT for colorectal cancer was performed. Studies were included if both cancer and control subjects underwent confirmatory testing. We also included studies that attempted to correct for verification bias by either performing colonoscopy on all subjects regardless of the FOBT result or by using longitudinal follow-up. We then compared the sensitivity, specificity, and other diagnostic characteristics of the studies that attempted to correct for verification (n=10) vs. those that did not correct for this bias (n=19).

RESULTS

The pooled sensitivity of guaiac-based FOBT for colorectal cancer of studies without verification bias was significantly lower than those studies with this bias [0.36 (95% CI 0.25-0.47) vs. 0.70 (95% CI 0.60-0.80), p=0.001]. The pooled specificity of the studies without verification bias was higher [0.96 (95% CI 0.94-0.97) vs. 0.88 (95% CI 0.84-0.91), p<0.005]. There was no significant difference in the area under the summary receiver operating characteristic curves. More sensitive chemical-based FOBT methods (e.g., Hemoccult® SENSA®) had a higher sensitivity but a lower specificity than standard guaiac methods.

CONCLUSIONS

The sensitivity of guaiac-based FOBT for colorectal cancer has been overestimated as a result of verification bias. This test may not be sensitive enough to serve as an effective screening option for colorectal cancer.

Performance improvements of stool-based screening tests

Stool testing is a widely accepted, non-invasive, technique for colorectal cancer (CRC) screening. Guaiac-based faecal occult blood test (gFOBT) screening has been proven to decrease CRC-related mortality; however gFOBT is hampered by a low sensitivity. Faecal immunochemical tests (FITs) have several advantages over gFOBT. First of all, FIT has a better sensitivity and higher uptake. Furthermore, the quantitative variant of the FIT allows choices on cut-off level for test-positivity according to colonoscopy resources available, personal risk profile, and/or intended detection rate in the screened population. Stool-based DNA (sDNA) tests aiming at the detection of specific DNA alterations may improve detection of CRC and adenomas compared to gFOBT screening, but large-scale population based studies are lacking. This review focuses on factors influencing test performance of those three stool based screening tests.

Comparison of immunochemical and guaiac-based fecal occult blood test in screening and surveillance for advanced colorectal neoplasms: a meta-analysis

OBJECTIVE

To systematically evaluate whether immunochemical fecal occult blood tests (iFOBT) could improve clinical performance and test accuracy in screening and surveillance for advanced colorectal neoplasms.

METHODS

Eligible articles were identified by searches of electronic databases. All randomized trials and diagnostic cohort trials directly comparing iFOBT with guaiac-based FOBT (gFOBT) were included. A statistical analysis was performed using RevMan 4.2.8. A sensitivity, specificity and summary receiver operating characteristic curve was performed using Meta Disc.

RESULTS

We identified five randomized trials and 11 diagnostic cohort trials. In the randomized trials, the detection rates of advanced colorectal neoplasms with iFOBT or gFOBT were 2.23 percent and 1.24 percent, respectively. The pooled odds ratio (OR) was 1.50 (95% CI 0.94-2.39). In cohort trials, the advanced neoplasm detection rates of iFOBT or gFOBT were 1.44 percent and 0.50 percent (OR 1.99, 95% CI 1.24-3.19) in the average-risk screened population, and were 8.8 percent and 7.1 percent (OR 1.27, 95% CI 1.01-1.60) in diagnosed patients scheduled for colonoscopy. The sensitivity of iFOBT (0.67, 95% CI 0.61-0.73) was superior to that of gFOBT (0.54, 95% CI 0.48-0.60), as well as the specificities (0.85, 95% CI 0.83-0.87 vs 0.80, 95% CI 0.78-0.82) and positive predictive values (0.41 vs 0.29) in cohort trials of diagnosed patients.

CONCLUSION

Our review suggests that iFOBT could perform better in increasing the detection rate of advanced colorectal neoplasm than gFOBT and possesses higher sensitivity and specificity in the surveillance of advanced colorectal neoplasm for patients.

Prediction of flare-ups of ulcerative colitis using quantitative immunochemical fecal occult blood test

AIM: To examine the feasibility of predicting the flare-up of ulcerative colitis (UC) before symptoms emerge using the immunochemical fecal occult blood test (I-FOBT).

METHODS: We prospectively measured fecal hemoglobin concentrations in 78 UC patients using the I-FOBT every 1 or 2 mo.

RESULTS: During a 20 mo-period, 823 fecal samples from 78 patients were submitted. The median concentration of fecal hemoglobin was 41 ng/mL (range: 0-392 500 ng/mL). There were three types of patients with regard to the correlation between I-FOBT and patient symptoms; the synchronous transition type with symptoms (44 patients), the unrelated type with symptoms (19 patients), and the flare-up predictive type (15 patients). In patients with the flare-up predictive type, the values of I-FOBT were generally low during the study period with stable symptoms. Two to four weeks before the flare-up of symptoms, the I-FOBT values were high. Thus, in these patients, I-FOBT could predict the flare-up before symptoms emerged.

CONCLUSION: Flare-up could be predicted by I-FOBT in approximately 20% of UC patients. These results warrant periodical I-FOBT in UC patients.

Colonoscopy-controlled intra-individual comparisons to screen relevant neoplasia: faecal immunochemical test vs. guaiac-based faecal occult blood test

BACKGROUND

Guaiac-based faecal occult blood tests (g-FOBTs) are most commonly used in colorectal cancer (CRC) screening programmes. Faecal immunochemical tests (FITs) are thought to be superior.

AIM

To compare performance of a g-FOBT and a quantitative FIT for detection of CRCs and advanced adenomas in a colonoscopy-controlled population.

METHODS

We assessed sensitivity and specificity of both FIT (OC-sensor) and g-FOBT (Hemoccult-II) prior to patients' scheduled colonoscopies.

RESULTS

Of the 62 invasive cancers detected in 1821 individuals, g-FOBT was positive in 46 and FIT in 54 (74.2% vs. 87.1%, P = 0.02). Among 194 patients with advanced adenomas, g-FOBT was positive in 35 and FIT in 69 (18.0% vs. 35.6%, P < 0.001). Sensitivity for screen relevant tumours (197 advanced adenomas and 28 stage I or II cancers) was 23.0% for g-FOBT and 40.5% for FIT (P < 0.001). Specificity of g-FOBT compared to FIT for the detection of cancer was 95.7% vs. 91.0%, P < 0.001) and for advanced adenomas (97.4% vs. 94.2%, P < 0.001).

CONCLUSIONS

Faecal immunochemical test is more sensitive for CRC and advanced adenomas. Sensitivity of FIT for screen relevant tumours, early-stage cancers and advanced adenomas, is significantly higher. Specificity of g-FOBT is higher compared with FIT.

Perspectives of colorectal cancer screening in Germany 2009

Adequate screening methods can decrease colorectal cancer (CRC) mortality. The guaiac test for fecal occult-blood (FOBT) is part of the German CRC Screening Program since 1970 and has evidence level Ia. In randomized multicenter-studies FOBT has an average sensitivity of 24% and decreases CRC mortality up to 30%. Immunological tests for human haemoglobin (iFOBT) show better performance characteristics than guaiac FOBT, with augmented sensitivity and specificity. However, the single tests show wide differences in diagnostic performance and iFOBT is not yet covered by insurance companies although it should replace the guaiac test for CRC screening. Visual colonoscopy, which was introduced to the German National Cancer Screening Program in 2002, is the gold standard for the diagnosis of colorectal neoplasia. From 2003 to 2007 more than 2.8 million examinations have been documented in Germany. The prevalence of adenomas is around 20% and of CRC about 0.7% to 1.0% of the screenings. Seventy percent of the carcinomas detected during screening are in an early stage (UICC I and II). Furthermore, screening colonoscopy is a cost saving procedure with a low complication rate (0.25% overall). Insurance companies save 216€ for each screening colonoscopy mainly by prevention of neoplasia due to polypectomy. In Germany, virtual colonography by computed tomography (CT) or magnetic resonance imaging still lacks standardization of the hard and software. In experienced centres the sensitivity for CRC and large polyps of CT colonography is comparable to colonoscopy but in meta-analyses the ranking is lower. New technologies like computer-aided colonoscopies with sheath or double balloon techniques are coming up as well as capsule colonoscopy, which sensitivity for large polyps is about 70%. Advised by his physician, the patient can choose his most acceptable examination method from this whole set of screening tools.

Screening for familial colorectal cancer with a sensitive immunochemical fecal occult blood test: a pilot study

OBJECTIVE

Colonoscopy is empirically recommended as the first choice screening strategy in first-degree relatives of patients with colorectal cancer (CRC). However, this strategy is accepted by less than 40% of the risk population and two-thirds of screened individuals and renders a normal exploration. This pilot study assessed the accuracy of a latex agglutination immunochemical fecal occult blood test (LA-FOBT) for detecting advanced colorectal neoplasm (cancer or adenomatous polyps > or =1 cm in size, with villous pattern or high grade dysplasia) in asymptomatic first-degree relatives of patients with CRC.

METHODS

One hundred and sixty-nine first-degree relatives of 135 index cases were prospectively included. All participants received a sensitive LA-FOBT (hemoglobin detection limit of 50 ng/ml buffer), and were invited to undergo colonoscopy. On the whole, 116 (69%) participants returned LA-FOBT and underwent colonoscopy.

RESULTS

LA-FOBT was positive in 19 of 116 (16%) cases. Colonoscopy detected neoplasms in 49 of 116 (42%) patients: 37 of 116 (32%) were nonadvanced adenomas and 12 of 116 (10%) advanced adenomas. LA-FOBT detected 10 of 12 (83%) advanced adenomas showing a sensitivity, specificity, positive predictive value, and negative predictive value of 83, 91, 53, and 98%, respectively. In patients with positive LA-FOBT, 1.9 colonoscopies were necessary for detecting one advanced adenoma, whereas in case of not performing this test 10 colonoscopies would be needed. Overall, approximately 80% of screening colonoscopies could be precluded using a LA-FOBT.

CONCLUSION

One-time screening with LA-FOBT successfully detects advanced colorectal adenomas and may save unnecessary colonoscopies in first-degree relatives of patients with CRC.

False negative fecal occult blood tests due to delayed sample return in colorectal cancer screening

Delayed return of immunochemical fecal occult blood test (iFOBT) samples to a laboratory might cause false negatives because of hemoglobin degradation. Quantitative iFOBT's became increasingly more accepted in colorectal cancer screening. Therefore, we studied the effects of delay between sampling and laboratory delivery on iFOBT performance. IFOBT positivity (>or=50 ng/ml hemoglobin) in colorectal cancer screening participants without delay between sampling and laboratory delivery (<5 days), was compared with positivity in participants with >or=5 and >or=7 days delay. Additionally, positive tests were stored at room temperature and retested 5 times within 10-14 days. The sampling date was reported by 61% (n = 3,767) of the participants: in 19% delay was >or=5 days and in 5% >or=7 days. Compared with no-delay, the adenoma detection rate was already significantly decreased after >or=5 days delay (OR 0.6; 95%CI 0.4-0.9). We retested iFOBT samples of 170 positives of which 139 (82%) had a colonoscopy: 45 (32%) had advanced adenomas (not colorectal cancer) and 8 (6%) had colorectal cancer. Mean daily fecal hemoglobin decrease was 29 ng/ml (S.D. 38 and median 11 ng/ml). In patients with advanced adenomas, hemoglobin in the sample was <50 ng/ml in 5 (11%) 2-3 days after the initial test and in 16 (36%) after 10-14 days. Seven days after the initial test, 2 (25%) colorectal cancer patients became false negative. Both had stage I colorectal cancer and initial values below 100 ng/ml, where the average for stage I is 532 ng/ml. Delay in sample return increased false negative immunochemical FOBT's. Mainly precursor lesions, but also colorectal cancer, will be missed due to delayed sample return.

Sensitivity, but not specificity, of a quantitative immunochemical fecal occult blood test for neoplasia is slightly increased by the use of low-dose aspirin, NSAIDs, and anticoagulants

OBJECTIVES

We evaluated the effect of the use of aspirin, nonsteroidal anti-inflammatory drugs (NSAIDS), and anticoagulants on the performance of immunochemical fecal occult blood test (I-FOBT).

METHODS

A prospective, cross-sectional study of 1,221 ambulatory patients having total colonoscopy after preparing three I-FOBTs. Information regarding the use of medications was collected from the health medical organization (HMO) database. I-FOBT was analyzed with the OC-MICRO instrument using both >or=75 and 100 ngHb/ml of buffer thresholds to determine positivity.

RESULTS

Colorectal cancer (CRC) was found in 17 and advanced adenomatous polyp (AAP) in 97 patients. A total of 212 patients were using aspirin/NSAIDS at the time of I-FOBT testing. Qualitative analysis for the detection of AAP/CRC reveals a trend for an increased sensitivity with aspirin/NSAIDS use. At the threshold 75 ng/ml for positivity, the sensitivity for the detection of AAP/CRC was 66.7% for aspirin/NSAIDS use vs. 51.2% for nondrug takers (P=0.20), and at the threshold of 100 ng/ml, the sensitivity was 66.7 vs. 46.5% (P=0.09). The specificity, however, was not affected by the use of aspirin/NSAIDS. At the threshold of 75 ng/ml for positivity, the specificity for the detection of AAP/CRC was 89.5% for aspirin/NSAIDS use vs. 91.2% for nondrug takers (P=0.47), and at the threshold of 100 ng/ml, the specificity was 92.17 vs. 93.0% (P=0.69). A total of 33 patients were using antithrombotics/coagulants at the time of I-FOBT testing. This group was small; however, it appears that their use was also associated with a trend for increased sensitivity and no change in specificity.

CONCLUSIONS

The use of aspirin/NSAIDS and anticoagulants was associated with a trend for increased sensitivity with no change in specificity for the detection of AAP/CRC. This study suggests that there is no need to stop these agents before I-FOBT testing.

Quantitative colonoscopic evaluation of relative efficiencies of an immunochemical faecal occult blood test and a sensitive guaiac test for detecting significant colorectal neoplasms

BACKGROUND

The guaiac faecal occult blood test (G-FOBT), HemoccultSENSA, is sensitive for significant neoplasms [colorectal cancer (CRC), advanced adenomatous polyps (AAP)], but faulted by non-specificity for human haemoglobin (Hb). Quantified, Hb- specific, immunochemical faecal occult blood tests (I-FOBT) are now used.

AIMS

To (i) compare I-FOBT and G-FOBT efficacy in identifying significant neoplasms and colonoscopy needs for positive tests and (ii) examine number of I-FOBTs needed and test threshold to use for equivalent or better sensitivity than G-FOBT and fewest colonoscopies for positive tests.

METHODS

Three daily G-FOBTs and I-FOBTs were collected and analysed in 330 patients scheduled for colonoscopy.

RESULTS

Colonoscopy found significant neoplasms in 32 patients, 6 CRC, 26 AAP. G-FOBT, sensitivity and specificity were 53.1% (17 neoplasms) and 59.4%, resulting in 8.1 colonoscopies/neoplasm. One I-FOBT having >or=50 ngHb/mL of buffer provided equivalent sensitivity but 94.0% specificity, resulting in 2.1 colonoscopies/neoplasm. By analysing the higher of two I-FOBTs at 50 ngHb/mL threshold, sensitivity increased to 68.8% (22 neoplasms, P = 0.063), specificity fell to 91.9% (P < 0.001), but still required 2.1 colonoscopies/neoplasm.

CONCLUSIONS

In this population, quantified I-FOBT had significantly better specificity than G-FOBT for significant neoplasms, reducing the number of colonoscopies needed/neoplasm detected. Results depend on the number of I-FOBTs performed and the chosen development threshold.

Nicht-invasive Diagnostik kolorektaler Tumore – Hat der Guaiac-Test ausgedient? / Non-invasive detection of colorectal cancer – do we still need the guaiac-based fecal occult blood test?

Aufgrund der leichten Handhabung und des Nachweises einer Mortalitätssenkung gilt der Nachweis von okkultem Blut (FOBT) im Stuhl derzeit als das am weitesten verbreitete Screeningverfahren für das kolorektale Karzinom. Als nachteilig erweisen sich allerdings eine unzureichende Sensitivität, insbesondere beim Nachweis früher Stadien und eine nach wie vor geringe Akzeptanz in der Bevölkerung. Vorläufige Daten zum Nachweis von Calprotectin oder der Tumor-M2-PK im Stuhl ließen bessere Screeningeigenschaften erwarten. Aber auch hier schränkt die geringe Sensitivität für frühe Vorstufen und unzureichende Spezifität mit zu erwartenden hohen Folgekosten die Tauglichkeit der Tests deutlich ein. Die kürzlich entwickelten immunologischen FOBTs (I-FOBT) erweisen sich als spezifischer und sensitiver. Sie beruhen auf dem Nachweis von humanem Hämoglobin mittels spezifischer Antikörper und sind somit unabhängig von diätetischen oder medikamentösen Faktoren, was zu einer deutlich besseren Akzeptanz führt. Sie gelten derzeit als kosteneffektivste Verfahren unter den nichtinvasiven Screeningmaßnahmen. Der Nachweis von Tumor-DNA im Stuhl eröffnet eine neue Ära zum frühzeitigen Nachweis kolorektaler Karzinome. Erste kleinere Studien weisen auf eine sehr gute Sensitivität dieser Verfahren hin. Sie lagen für kolorektale Karzinome zwischen 62–91% und für Adenome zwischen 26–73% bei mit 93–100% sehr guter Spezifität. Als nachteilig im Vergleich zu den derzeit verfügbaren Screeningtests erweisen sich allerdings die vergleichsweise hohen Kosten.

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.

Tumor pyruvate kinase isoenzyme type M2 and immunochemical fecal occult blood test: performance in screening for colorectal cancer

OBJECTIVES

Immunochemical fecal occult blood test (FOBT) and determination of tumor pyruvate kinase isoenzyme type M2 (TuM2-PK) in stool samples may be valuable new screening tools for colorectal cancer (CRC). The aim of this study was to compare the accuracy of fecal TuM2-PK testing with immunochemical FOBT in patients with CRC or adenomas.

METHODS

A total of 52 patients with CRC were analyzed, 47 with colorectal adenomas, and 63 matched controls with a normal colonoscopy. Nineteen additional patients with inflammatory bowel disease were tested to determine influence of inflammation. Stool samples were analyzed with two immunochemical FOBTs, Immo-care and OC-Light, and with a commercial enzyme-linked immunosorbent assay for TuM2-PK.

RESULTS

In patients with CRC, the sensitivity of TuM2-PK, Immo-care and OC-Light was respectively 85, 92 and 94%. In patients with adenomas, the sensitivity was respectively 28, 40 and 34%. Specificity for these tests was 90% for TuM2-PK and 97% for both immunochemical FOBTs. All tests showed a high positivity rate in patients with inflammatory bowel disease (79% for TuM2-PK and Immo-care, and 89% for OC-Light).

CONCLUSION

Both immunochemical FOBTs appear valuable and are sensitive tests for CRC screening. TuM2-PK does not have supplemental value for screening for CRC because of a lower sensitivity and specificity. None of these tests is sensitive enough for detection of advanced adenomas. Patients with inflammatory bowel disease should be excluded from CRC screening when using immunochemical FOBT or TuM2-PK.

Screening for Colorectal Neoplasms With New Fecal Occult Blood Tests: Update on Performance Characteristics

BACKGROUND

One type of fecal occult blood test (FOBT), the unrehydrated guaiac fecal occult blood test (GT), is recommended by the United States Preventive Services Task Force and the Institute of Medicine for use in screening programs, but it has relatively low sensitivity as a single test for detecting advanced colonic neoplasms (cancer and adenomatous polyps > or = 1 cm in diameter). Thus, improving the sensitivity of FOBT should make colon cancer screening programs that use these tests more effective.

METHODS

We assessed prospectively the performance characteristics of two newer FOBTs in 5841 subjects at average risk for colorectal cancer in a large group-model managed care organization. The tests evaluated included a sensitive GT, a fecal immunochemical test (FIT), and the combination of both tests. Patients with positive and negative test results were advised to have colonoscopy and sigmoidoscopy, respectively. Sensitivity and specificity for detecting advanced neoplasms in the left colon within 2 years after the FOBT screening were evaluated for the two tests administered separately and in combination.

RESULTS

A total of 139 patients were diagnosed with advanced colorectal neoplasms (n = 14 cancers, n = 128 adenomas) within the 2 years following their initial FOBT screening. Sensitivity for detecting cancer was 81.8% (95% confidence interval [CI] = 47.8% to 96.8%) for the FIT alone and 64.3% (95% CI = 35.6% to 86.0%) for the sensitive GT and the combination test. Sensitivity for detecting advanced colorectal adenomas was 41.3% (95% CI = 32.7% to 50.4%) for the sensitive GT, 29.5% (95% CI = 21.4% to 38.9%) for the FIT, and 22.8% (95% CI =16.1% to 31.3%) for the combination test. Specificity for detecting cancer and adenomas was 98.1% (95% CI = 97.7% to 98.4%) and 98.4% (95% CI = 98.0% to 98.7%), respectively, for the combination test; 96.9% (95% CI = 96.4% to 97.4%) and 97.3% (95% CI = 96.8% to 97.7%), respectively, for the FIT; and 90.1% (95% CI = 89.3% to 90.8%) and 90.6% (95% CI = 89.8% to 91.4%), respectively, for the sensitive GT.

CONCLUSIONS

The FIT has high sensitivity and specificity for detecting left-sided colorectal cancer, and it may be a useful replacement for the GT.

Sensitivity of latex agglutination faecal occult blood test in the Florence District population-based colorectal cancer screening programme

We evaluated the sensitivity for colorectal cancer (CRC) of the latex agglutination test (LAT), an immunochemical test routinely used in the Florence District screening programme since 2000. Sensitivity was calculated by the proportional interval cancer incidence method in a population of 27,503 consecutive subjects screened in 2000-2002, interval cancers being identified by linkage to the Tuscany Cancer Registry files. Sensitivity was calculated overall and by gender, age, time since last negative LAT, CRC site, and rank of screening. Overall 1- and 2-year sensitivity estimates were 80.7 and 71.5%, respectively, suggesting that faecal occult blood testing screening sensitivity may be suboptimal due to testing or programme quality problems. Increasing screening sensitivity might be achieved if the detection rate of advanced adenomas could be increased without unacceptable loss in specificity.

Can quantification of faecal occult blood predetermine the need for colonoscopy in patients at risk for non-syndromic familial colorectal cancer?

BACKGROUND

Patients at risk for non-syndromic (Lynch or polyposis) familial colorectal neoplasia undergo colonoscopic surveillance at intervals determined by clinically ascertained protocols. The quantitative immunochemical faecal occult blood test for human haemoglobin is specific and sensitive for significant colorectal neoplasia (cancer or advanced adenomatous polyp).

AIM

To determine immunochemical faecal occult blood test efficacy for identifying significant neoplasia in at-risk patients undergoing elective colonoscopy.

METHODS

We retrospectively identified consecutive at-risk patients who provided three immunochemical faecal occult blood tests before colonoscopy. Quantitative haemoglobin analysis was performed by the OC-MICRO automated instrument using the 100 ng Hb/mL threshold to determine positivity.

RESULTS

In 252 at-risk patients undergoing colonoscopy; five had cancer, 14 an advanced adenoma and 46 a non-advanced adenoma. The immunochemical faecal occult blood test was positive in 31 patients (12.3%). Sensitivity, specificity, positive and negative predictive values for cancer were: 100%, 90%, 16% and 100%, and for all significant neoplasia: 74%, 93%, 45% and 98%. With 88% fewer colonoscopies, all colorectal cancers and 74% of all significant neoplasia would have been identified by this one-time immunochemical faecal occult blood test screening.

CONCLUSIONS

A sensitive, non-invasive, interval screening test might be useful to predetermine the need for colonoscopy in this at-risk population and minimize unnecessary examinations. This favourable retrospective evaluation will be extended to a prospective study.