Guaiac-based Fecal Occult Blood Test Research Articles

PWE-103 Participation, Positivity and Outcomes in The Nepali Community Invited for Bowel Cancer Screening – A Feasibility Study

<h3>Introduction</h3> The NHS Bowel Cancer Screening Programme (BCSP) offers biennial screening for all adults in England aged 60–74 years using a guaiac-based faecal occult blood test (gFOBt). This feasibility study investigated anecdotal evidence that people who originate from Nepal account for a higher than expected proportion of gFOBt-positive subjects who have a normal outcome at follow-up colonoscopy (false-positive). The BCSP Southern Hub serves several geographical areas with relatively high proportions of Nepali subjects (<i>e.g.</i> Aldershot, Reading and Ashford). <h3>Methods</h3> Data for subjects aged 60–74 invited for screening in the Southern Hub (roll-out to September 2014) were extracted from the BCSP database (BCSS). Because information about subjects’ ethnicity is not recorded on BCSS, Nepali subjects were identified using an algorithm that was based on surname and postcode of residence (subject residing in an area where ≥8% of the BCSP-invited population had a Nepali surname). Data on uptake, gFOBt-positivity and false-positivity were compared between Nepali and non-Nepali men and women invited for screening. <h3>Results</h3> We identified 5,274 Nepali subjects (43.5% women) amongst the 6,218,071 subjects invited for screening during the study period. Compared with the non-Nepali population, uptake of screening was significantly higher amongst Nepalis (61.9% vs. 58.3%; odds ratio [OR] 1.16, 95% Confidence Interval [95%CI] 1.10,1.23), more so amongst Nepali men (OR 1.26, 95%CI 1.17,1.35) than women (OR 1.09, 95%CI 1.00,1.19). Positivity was high in the Nepali population (7.6% vs. 2.0%; OR 4.01, 95%CI 3.53,4.57) and higher for women (OR 5.13, 95%CI 4.22,6.23) than men (OR 3.20, 95%CI 2.69,3.81). False-positivity was markedly higher in the Nepali population (OR 2.37 95%CI 1.77,3.18). More than half of gFOBt-positive Nepali women (50.6%) had a normal outcome at colonoscopy (false-positive), compared with 24.4% in non-Nepali women (OR 3.18 95%CI 2.09,4.84). The proportion of Nepali men with a false-positive outcome was also greater than amongst non-Nepali men (OR 1.75, 95%CI 1.12,2.75). <h3>Conclusion</h3> Compared with non-Nepali gFOBT-positive subjects, false-positivity was high in the Nepali community living in the south of England. The reasons for high false-positivity, implications for colonoscopy resource and exposure of subjects to unnecessary risk will be addressed in further work. The study area will be extended to include other Nepali communities living in London and a validation exercise will be undertaken to test the algorithm used to identify Nepali subjects. <h3>Disclosure of Interest</h3> None Declared

Immunochemical fecal occult blood tests for colorectal cancer screening: Point-of-care tests are not tenable for a quality-assured program

Fecal immunochemical tests for hemoglobin (FIT) offer several advantages over guaiac-based fecal occult blood testing in colorectal cancer screening, e. g. regarding diagnostic accuracy and participation rates. There are different FITs on the market, namely qualitative FITs (point-of-care tests) and quantitative FITs. Although the European Guidelines for quality assurance in colorectal cancer screening only recommend quantitative FITs, there are continued endeavors to question this and to also allow qualitative FITs as an option. In this commentary, we explain the problems that qualitative FITs pose in terms of quality assurance, particularly regarding the sustained control of the positivity threshold. We further show that various arguments raised in favor of qualitative FITs do not stand up to a critical and rational examination. The use of qualitative FITs is thus not a tenable option for a quality-assured screening program.

A Clinician's Guide to Fecal Occult Blood Testing for Colorectal Cancer.

Colorectal cancer (CRC) is a significant healthcare issue, with substantial morbidity and mortality. Screening for CRC is essential in the prevention and treatment of this disease. The two most common CRC screening modalities are colonoscopy and the stool-based occult blood test, with two types of stool-based occult blood tests: the guaiac-based fecal occult blood test (FOBT) and the immunochemical FOBT. Despite many similarities, these two stool tests are different and often are confused in clinical practice. In an effort to improve awareness of these testing modalities, this review provides extensive information on both of these FOBTs, as well as discusses comparisons in the literature between these stool-based blood tests and other screening modalities such as stool DNA and colonoscopy.

Mo1156 Meta-Analysis on Guaiac-Based Fecal Occult Blood Tests Versus Fecal Immunochemical Tests for Colorectal Cancer Screening in Average-Risk Individuals

Mo1156 Meta-Analysis on Guaiac-Based Fecal Occult Blood Tests Versus Fecal Immunochemical Tests for Colorectal Cancer Screening in Average-Risk Individuals

Evaluation of a 5-Marker Blood Test for Colorectal Cancer Early Detection in a Colorectal Cancer Screening Setting.

In initial studies that included colorectal cancer patients undergoing diagnostic colonoscopy, we had identified a serum marker combination able to detect colorectal cancer with similar diagnostic performance as fecal immunochemical test (FIT). In this study, we aimed to validate the results in participants of a large colorectal cancer screening study conducted in the average-risk, asymptomatic screening population. We tested serum samples from 1,200 controls, 420 advanced adenoma patients, 4 carcinoma in situ patients, and 36 colorectal cancer patients with a 5-marker blood test [carcinoembryonic antigen (CEA)+anti-p53+osteopontin+seprase+ferritin]. The diagnostic performance of individual markers and marker combinations was assessed and compared with stool test results. AUCs for the detection of colorectal cancer and advanced adenomas with the 5-marker blood test were 0.78 [95% confidence interval (CI), 0.68-0.87] and 0.56 (95% CI, 0.53-0.59), respectively, which now is comparable with guaiac-based fecal occult blood test (gFOBT) but inferior to FIT. With cutoffs yielding specificities of 80%, 90%, and 95%, the sensitivities for the detection of colorectal cancer were 64%, 50%, and 42%, and early-stage cancers were detected as well as late-stage cancers. For osteopontin, seprase, and ferritin, the diagnostic performance in the screening setting was reduced compared with previous studies in diagnostic settings while CEA and anti-p53 showed similar diagnostic performance in both settings. Performance of the 5-marker blood test under screening conditions is inferior to FIT even though it is still comparable with the performance of gFOBT. CEA and anti-p53 could contribute to the development of a multiple marker blood-based test for early detection of colorectal cancer.

Colorectal Cancer Screening: Stool DNA and Other Noninvasive Modalities.

Colorectal cancer screening dates to the discovery of pre-cancerous adenomatous tissue. Screening modalities and guidelines directed at prevention and early detection have evolved and resulted in a significant decrease in the prevalence and mortality of colorectal cancer via direct visualization or using specific markers. Despite continued efforts and an overall reduction in deaths attributed to colorectal cancer over the last 25 years, colorectal cancer remains one of the most common causes of malignancy-associated deaths. In attempt to further reduce the prevalence of colorectal cancer and associated deaths, continued improvement in screening quality and adherence remains key. Noninvasive screening modalities are actively being explored. Identification of specific genetic alterations in the adenoma-cancer sequence allow for the study and development of noninvasive screening modalities beyond guaiac-based fecal occult blood testing which target specific alterations or a panel of alterations. The stool DNA test is the first noninvasive screening tool that targets both human hemoglobin and specific genetic alterations. In this review we discuss stool DNA and other commercially available noninvasive colorectal cancer screening modalities in addition to other targets which previously have been or are currently under study.

Systematic review with meta-analysis: faecal occult blood tests show lower colorectal cancer detection rates in the proximal colon in colonoscopy-verified diagnostic studies.

The performance of faecal occult blood tests (FOBTs) to screen proximally located colorectal cancer (CRC) has produced inconsistent results. To assess in a meta-analysis, the diagnostic accuracy of FOBTs for relative detection of CRC according to anatomical location of CRC. Diagnostic studies including both symptomatic and asymptomatic cohorts assessing performance of FOBTs for CRC were searched from MEDINE and EMBASE. Primary outcome was accuracy of FOBTs according to the anatomical location of CRC. Bivariate random-effects model was used. Subgroup analyses were performed to evaluate test performance of guaiac-based FOBT (gFOBT) and immunochemical-based FOBT (iFOBT). Thirteen studies, with 17 cohorts, reporting performance of FOBT were included; a total of 26 342 patients (mean age 58.9 years; 58.1% male) underwent both colonoscopy and FOBT. Pooled sensitivity, specificity, positive likelihood ratio and negative likelihood ratio of FOBTs for CRC detection in the proximal colon were 71.2% (95% CI 61.3-79.4%), 93.6% (95% CI 90.7-95.7%), 11.1 (95% CI 7.8-15.8) and 0.3 (95% CI 0.2-0.4) respectively. Corresponding findings for CRC detection in distal colon were 80.1% (95% CI 70.9-87.0%), 93.6% (95% CI 90.7-95.7%), 12.6 (95% CI 8.8-18.1) and 0.2 (95% CI 0.1-0.3). The area-under-curve for FOBT detection for proximal and distal CRC were 90% vs. 94% (P = 0.0143). Both gFOBT and iFOBT showed significantly lower sensitivity but comparable specificity for the detection of proximally located CRC compared with distal CRC. Faecal occult blood tests, both guaiac- and immunochemical-based, show better diagnostic performance for the relative detection of colorectal cancer in the distal colon than in the proximal bowel.

Recommendations for a step-wise comparative approach to the evaluation of new screening tests for colorectal cancer.

BACKGROUNDNew screening tests for colorectal cancer continue to emerge, but the evidence needed to justify their adoption in screening programs remains uncertain.METHODSA review of the literature and a consensus approach by experts was undertaken to provide practical guidance on how to compare new screening tests with proven screening tests.RESULTSFindings and recommendations from the review included the following: Adoption of a new screening test requires evidence of effectiveness relative to a proven comparator test. Clinical accuracy supported by programmatic population evaluation in the screening context on an intention‐to‐screen basis, including acceptability, is essential. Cancer‐specific mortality is not essential as an endpoint provided that the mortality benefit of the comparator has been demonstrated and that the biologic basis of detection is similar. Effectiveness of the guaiac‐based fecal occult blood test provides the minimum standard to be achieved by a new test. A 4‐phase evaluation is recommended. An initial retrospective evaluation in cancer cases and controls (Phase 1) is followed by a prospective evaluation of performance across the continuum of neoplastic lesions (Phase 2). Phase 3 follows the demonstration of adequate accuracy in these 2 prescreening phases and addresses programmatic outcomes at 1 screening round on an intention‐to‐screen basis. Phase 4 involves more comprehensive evaluation of ongoing screening over multiple rounds. Key information is provided from the following parameters: the test positivity rate in a screening population, the true‐positive and false‐positive rates, and the number needed to colonoscope to detect a target lesion.CONCLUSIONSNew screening tests can be evaluated efficiently by this stepwise comparative approach. Cancer 2016;122:826–39. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.

Effectiveness of screening for colorectal cancer with a faecal occult-blood test, in Finland

BackgroundScreening for colorectal cancer (CRC) with guaiac-based faecal occult-blood test (FOBT) has been reported to reduce CRC mortality in randomised trials in the 1990s, but not in routine screening, so...

European Code against Cancer, 4th Edition: Cancer screening

In order to update the previous version of the European Code against Cancer and formulate evidence-based recommendations, a systematic search of the literature was performed according to the methodology agreed by the Code Working Groups. Based on the review, the 4th edition of the European Code against Cancer recommends:“Take part in organized cancer screening programmes for:•Bowel cancer (men and women)•Breast cancer (women)•Cervical cancer (women).”Organized screening programs are preferable because they provide better conditions to ensure that the Guidelines for Quality Assurance in Screening are followed in order to achieve the greatest benefit with the least harm. Screening is recommended only for those cancers where a demonstrated life-saving effect substantially outweighs the potential harm of examining very large numbers of people who may otherwise never have, or suffer from, these cancers, and when an adequate quality of the screening is achieved. EU citizens are recommended to participate in cancer screening each time an invitation from the national or regional screening program is received and after having read the information materials provided and carefully considered the potential benefits and harms of screening. Screening programs in the European Union vary with respect to the age groups invited and to the interval between invitations, depending on each country's cancer burden, local resources, and the type of screening test usedFor colorectal cancer, most programs in the EU invite men and women starting at the age of 50–60 years, and from then on every 2 years if the screening test is the guaiac-based fecal occult blood test or fecal immunochemical test, or every 10 years or more if the screening test is flexible sigmoidoscopy or total colonoscopy. Most programs continue sending invitations to screening up to the age of 70–75 years.For breast cancer, most programs in the EU invite women starting at the age of 50 years, and not before the age of 40 years, and from then on every 2 years until the age of 70–75 years.For cervical cancer, if cytology (Pap) testing is used for screening, most programs in the EU invite women starting at the age of 25–30 years and from then on every 3 or 5 years. If human papillomavirus testing is used for screening, most women are invited starting at the age of 35 years (usually not before age 30 years) and from then on every 5 years or more. Irrespective of the test used, women continue participating in screening until the age of 60 or 65 years, and continue beyond this age unless the most recent test results are normal.

Comparison of Guaiac-Based and Immunochemical Fecal Occult Blood Tests for Colorectal Cancer Screening in an Alaska Native Population with High Prevalence of Helicobacter Pylori Infection.

Comparison of Guaiac-Based and Immunochemical Fecal Occult Blood Tests for Colorectal Cancer Screening in an Alaska Native Population with High Prevalence of Helicobacter Pylori Infection.

PWE-280 Faecal occult blood testing (FOBT) and interval bowel cancers-results of a multicentre study

<h3>Introduction</h3> We aimed to assess the incidence and demographics of interval cancers (cancers diagnosed within 2 years of a negative FOBT screening) in the eligible population of the East Midlands region. <h3>Method</h3> The National Bowel Cancer Audit Programme data from three centres (Queens Medical Centre, Nottingham; Royal Derby Hospital and Sherwood Forest Hospitals) for all colorectal cancers in the screening age group (60–74 years)over a 2-year period (August 2011–August 2013) were linked for their FOBT screening status (BCSP database/Eastern Hub). Three cancer groups were identified: interval cancers, screen detected (positive FOBT) and those in the non-uptake group (eligible patients who declined screening). Tumours at and distal to the splenic flexure were classed as left sided tumours. Dukes C and D tumours were classed as advanced tumours. All three centres were in incident rounds of screening. <h3>Results</h3> Of the 521 colorectal cancers identified, 128 (25%) were interval cancers, 162(31%) were screen detected and 231 (44%) were from the non-uptake group. Gender, ethnicity and Deprivation index were comparable between the three groups. The mean age in the interval cancer group was greater (67 yrs) compared to the screen detected (66 yrs) (<i>p = 0.005</i>). The interval cancer group had a higher incidence of right sided cancers (38% vs. 25% and 29%; <i>X</i>²=6.59; p = 0.033) compared to the screen-detected and non-uptake groups. Cancers detected in the interval cancer group were of a more advanced stage (Dukes C/D) (70% vs. 34% and 54%; <i>X</i>²=37.2;<i>p &lt; 0.005</i>) in comparison to screen-detected and non-uptake groups. The one year mortality in the interval cancer group (16%) was higher than the non-uptake group (12%) and the screen detected group (3%) (16%vs12% and 3%; X2=13.8;<i>p &lt; 0.005</i>). <h3>Conclusion</h3> A quarter of colorectal cancers identified in our screening-eligible population were interval cancers. We highlight the probability that these cancers were ‘missed’ by the guaiac-based FOBT screening tests. The interval cancer group also had poorer outcomes when compared to the screen-detected group. We highlight the need for a test with a lower false negative rate for population based FOBT screening. <h3>Disclosure of interest</h3> None Declared.

Evidence of Mortality Reduction from FIT in Italy

Randomized, controlled trial findings support guaiac-based fecal occult blood testing (FOBT) and sigmoidoscopy for colorectal cancer (CRC) mortality reduction but have not been conducted for colonoscopy, barium enema, computed tomographic colonography, or fecal immunochemical testing (FIT) for blood. FIT has higher adherence rates and better performance characteristics than guaiac-based FOBT. Biennial FIT-based screening programs were introduced in some Italian regions in 2002–2004 and in other regions in 2008–2009. In …

To Increase Adherence to Screening, Just Make the Patient an Appointment

In England, colorectal cancer screening is done using guaiac-based fecal occult blood testing. Flexible sigmoidoscopy at age ≥55 years is also being

The impact of screening on colorectal cancer mortality and incidence: has it really made a difference?

About sixty percent of the US population of those age fifty and older are currently up to date with colorectal cancer screening recommendations. Has this level of screening made a difference for reducing colorectal cancer (CRC) incidence and/or mortality? Randomized controlled trials of guaiac-based fecal occult blood tests, which have relatively low sensitivity but high specificity for CRC, have shown a modest effect but with a long-term reduction in CRC mortality. Newer fecal immunochemical tests are expected to have a greater effect. Randomized controlled trials of flexible sigmoidoscopy have also demonstrated a reduction in CRC mortality. Observational studies of screening colonoscopy suggest an effect of greater than fifty percent reduction in CRC mortality. We have assessed past trends of colorectal cancer screening in the US population which suggest that more than fifty percent of the decline in colorectal cancer mortality can be attributed to the increased acceptance and uptake in colorectal cancer screening. Current and future levels of increased screening could provide for even larger reductions for the USA. Colorectal cancer screening has and will continue to make a significant impact on reducing colorectal cancer mortality.

Comparing the effectiveness of competing tests for reducing colorectal cancer mortality: a network meta-analysis

Comparative effectiveness data pertaining to competing colorectal cancer (CRC) screening tests do not exist but are necessary to guide clinical decision making and policy. To perform a comparative synthesis of clinical outcomes studies evaluating the effects of competing tests on CRC-related mortality. Traditional and network meta-analyses. Two reviewers identified studies evaluating the effect of guaiac-based fecal occult blood testing (gFOBT), flexible sigmoidoscopy (FS), or colonoscopy on CRC-related mortality. gFOBT, FS, colonoscopy. Traditional meta-analysis was performed to produce pooled estimates of the effect of each modality on CRC mortality. Bayesian network meta-analysis (NMA) was performed to indirectly compare the effectiveness of screening modalities. Multiple sensitivity analyses were performed. Traditional meta-analysis revealed that, compared with no intervention, colonoscopy reduced CRC-related mortality by 57% (relative risk [RR] 0.43; 95% confidence interval [CI], 0.33-0.58), whereas FS reduced CRC-related mortality by 40% (RR 0.60; 95% CI, 0.45-0.78), and gFOBT reduced CRC-related mortality by 18% (RR 0.82; 95% CI, 0.76-0.88). NMA demonstrated nonsignificant trends favoring colonoscopy over FS (RR 0.71; 95% CI, 0.45-1.11) and FS over gFOBT (RR 0.74; 95% CI, 0.51-1.09) for reducing CRC-related deaths. NMA-based simulations, however, revealed that colonoscopy has a 94% probability of being the most effective test for reducing CRC mortality and a 99% probability of being most effective when the analysis is restricted to screening studies. Randomized trials and observational studies were combined within the same analysis. Clinical outcomes studies demonstrate that gFOBT, FS, and colonoscopy are all effective in reducing CRC-related mortality. Network meta-analysis suggests that colonoscopy is the most effective test.

Faecal haemoglobin concentration measurement: an essential examination

Guaiac-based faecal occult blood tests (gFOBT) have some limited applications in colorectal cancer screening programmes, but are not recommended for assessment of patients with lower abdominal symptoms and are badly used in clinical practice. Faecal immunochemical tests for haemoglobin (FIT) are replacing gFOBT in screening programmes because they have many advantages, including that faecal haemoglobin concentration can be quantitated using automated immunoturbidimetry. In countries with limited colonoscopy resources, the services are now becoming overwhelmed with referrals from primary care as well as from screening and surveillance programmes. Options to deal with this include reinforcing current objective-based guidelines, expanding colonoscopy resources, or using simple faecal tests to assess patients presenting with suspected colorectal disease. There are many data on use of FIT in screening for detection of colorectal cancer and advanced adenoma: newer data on the use of FIT in primary care show that, although faecal haemoglobin is not a good diagnostic rule-in test for colorectal disease, it has very high negative predictive value, making it a very good rule-out test. Along with use in surveillance programmes, this application of faecal haemoglobin assays would improve use of colonoscopy services and facilitate patient care. Faecal haemoglobin analyses should become an essential examination.

Colorectal cancer screening at community health centers: A survey of clinicians' attitudes, practices, and perceived barriers.

ObjectiveColorectal cancer (CRC) screening rates remain lower among some racial/ethnic groups and individuals with low income or educational attainment who are often cared for within community health centers (CHCs). We surveyed clinicians in a network of CHCs to understand their attitudes, practice patterns, and perceived barriers to CRC screening.MethodsA clinician survey was conducted in 2013 within the Community Health Applied Research Network (CHARN).Results180 clinicians completed the survey (47.9% response rate). Participants had an average of 11.5 (SD: 9.8) years in practice, 62% were female, and 57% were physicians. The majority of respondents somewhat agreed (30.2%) or strongly agreed (57.5%) that colonoscopy was the best screening test. However, only 15.8% of respondents strongly agreed and 32.2% somewhat agreed that colonoscopy was readily available for their patients. Fecal immunochemical testing (FIT), a type of fecal occult blood test (FOBT), was viewed less favorably; 24.6% rated FIT as very effective.ConclusionsAlthough there are no data showing that screening colonoscopy is superior to FIT, CHC clinicians believe colonoscopy is the best CRC screening test for their patients, despite the high prevalence of financial barriers to colonoscopy. These attitudes could be due to lack of knowledge about the evidence supporting long-term benefits of fecal occult blood testing (FOBT), lack of awareness about the improved test characteristics of FIT compared to older guaiac-based FOBT, or the absence of systems to ensure adherence to regular FOBT screening. Interventions to improve CRC screening at CHCs must address clinicians' negative attitudes towards FIT.

Advances in Fecal Occult Blood Tests: the FIT revolution.

There is a wide choice of fecal occult blood tests (FOBTs) for colorectal cancer screening. Goal: To highlight the issues applicable when choosing a FOBT, in particular which FOBT is best suited to the range of screening scenarios. Four scenarios characterize the constraints and expectations of screening programs: (1) limited colonoscopy resource with a need to constrain test positivity rate; (2) a priority for maximum colorectal neoplasia detection with little need to constrain colonoscopy workload; (3) an “adequate” endoscopy resource that allows balancing the benefits of detection with the burden of service provision; and (4) a need to maximize participation in screening. Guaiac-based FOBTs (gFOBTs) have significant deficiencies, and fecal immunochemical tests (FITs) for hemoglobin have emerged as better tests. gFOBTs are not sensitive to small bleeds, specificity can be affected by diet or drugs, participant acceptance can be low, laboratory quality control opportunities are limited, and they have a fixed hemoglobin concentration cutoff determining positivity. FITs are analytically more specific, capable of quantitation and hence provide flexibility to adjust cutoff concentration for positivity and the balance between sensitivity and specificity. FITs are clinically more sensitive for cancers and advanced adenomas, and because they are easier to use, acceptance rates are high. Conclusions: FOBT must be chosen carefully to meet the needs of the applicable screening scenario. Quantitative FIT can be adjusted to suit Scenarios 1, 2 and 3, and for each, they are the test of choice. FITs are superior to gFOBT for Scenario 4 and gFOBT is only suitable for Scenario 1.

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.