Guaiac-based Test Research Articles

Fecal occult blood test for colorectal cancer screening

Screening programs for colorectal cancer (CRC) are standard in most developed countries because they reduce mortality and are cost-effective. Within them, colonoscopy allows to directly visualize the colon and remove neoplastic lesions. However, it is an expensive exam with low adherence in asymptomatic individuals. The fecal occult blood test (FOBT) is a low-cost and risk-free method for the user, which results in a high rate of adherence, explaining its use in most screening programs. This article analyzes the effectiveness of different fecal occult blood tests in screening programs. The main conclusions are that the sensitivity of the guaiac-based chemical test for the detection of colorectal cancer is lower than that observed with qualitative and quantitative immunological tests. Automated quantitative methods allow objective readings independent of the operator and the reaction reading time, necessary for the analysis of large numbers of samples. The participation rate with immunological FOBTs is higher than with chemical ones, which is why they are preferred by the different countries that have screening programs. The use of quantitative tests allows stratification of symptomatic and asymptomatic patients at higher risk, in the screening programs.

Comparative evaluation of two colorectal cancer screening campaigns using different faecal occult blood tests in a French area

ObjectiveThe aim of this study was to compare quality performance of the first colorectal cancer (CRC) screening campaigns (C) with the OC Sensor® Faecal Immunological Test (FIT) (C7 from 2016 to 2017) and the Hemoccult® guaiac-based test (C1 from 2004 to 2006). MethodsThe participation rate of the eligible population, screening fecal occult blood test (FOBT) performance indices, CRC and adenoma detection rate and time interval between test positivity and colonoscopy were studied. ResultsIn C7, 35.9 % of the eligible population completed the screening process versus 47.6 % in C1 (p < 0.0001). The positivity rate was of 4.3 % for OC Sensor® FIT and 2.3 % for Hemoccult® test (p < 0.0001). A total of 3,252 colonoscopies were performed in C7 versus 2,005 in C1; 246 CRCs and 1,160 advanced adenomas (AA) were detected in C7 compared to 140 CRCs and 491 AA in C1 (p < 0.0001). The FOBT cancer detection rate increased significantly from 1.4 ‰ to 2.9 ‰ between the two campaigns, as did the FOBT AA detection rate, from 5.7 ‰ to 13.7 ‰. During C7, the mean time for colonoscopy after a positive FIT result was 84.3 days [95 % CI: 77.9–90.7]. There was no significant difference between the stages at diagnosis according to the time for colonoscopy within the first 6 months. ConclusionsCRC and AA detection rates increased significantly between the two campaigns. Longer follow-up will be required to show a potential decrease in the incidence of invasive CRCs.

Fecal Occult Blood Tests Should Not Be Used for Diagnostic Indications

The fecal occult blood test (FOBT) — including the guaiac-based (gFOBT) and fecal immunochemical test (FIT) — is recommended only for colorectal cancer

Colorectal Cancer Screening With Traditional and New-generation Fecal Immunochemical Tests: A Critical Review of Fecal Occult Blood Tests.

Previous randomized studies suggest that fecal occult blood test (FOBT) screening can reduce mortality from colorectal cancer (CRC). Our aim was to review the current status of FOBTs in CRC screening. FOB is measured using either the traditional guaiac-based tests or more recently introduced fecal immunochemical tests (FITs). FITs have several advantages over guaiac-based FOBTs, including higher sensitivity and specificity, resulting in improved clinical performance and higher efficiency. Another advantage in population screening according to European Guidelines for quality assurance in CRC screening is that FITs can be automated and user can adjust the cut-off at which a positive result is reported. In population-based screening, all those testing positively with any FOBT should be referred for colonoscopy. Conclusion: Although a plethora of FOBTs are available on the market, relatively few have been extensively tested for clinical sensitivity and specificity in CRC screening. Current data imply that new FITs have superior test characteristics as compared with guaiac-based FOBTs. The latest development in the field is represented by the proteomic-based tests that may further reduce false-negative rates in CRC screening. Simple stool sample preservation and automatic analysis are other important issues in population-based screening for CRC.

Use of Fecal Occult Blood Testing as a Diagnostic Tool for Clinical Indications: A Systematic Review and Meta-Analysis.

Fecal occult blood tests (FOBTs) are validated only for colorectal cancer (CRC) screening, but are commonly used as a diagnostic test in other clinical settings. We performed a systematic review to assess performance characteristics of FOBT as a diagnostic test for clinical indications. Bibliographic databases were searched to identify studies in adult patients with a specific gastrointestinal symptom or condition who underwent FOBT and a reference test and provided data on diagnoses. Our primary end point was sensitivity. Risk of bias was assessed with the QUADAS-2 tool. Twenty-two studies met the inclusion criteria: 12 in iron deficiency anemia (IDA) (5 fecal immunochemical (FIT) and 7 guaiac based), 8 in ulcerative colitis (FIT), and 2 in acute diarrhea (guaiac based). Only 2 studies had low risk of bias on all domains of the QUADAS-2. On meta-analysis, FOBT had a sensitivity of 0.58 (95% confidence interval [CI] 0.53-0.63) and a specificity of 0.84 (95% CI 0.75-0.89) in predicting presumptive causes of IDA at endoscopy, with comparable results for guaiac-based tests and FIT. Sensitivity was higher for CRC (0.83) than non-CRC lesions (0.54). FIT had a sensitivity of 0.72 (95% CI 0.57-0.84) and a specificity of 0.80 (95% CI 0.67-0.89) in predicting endoscopic activity in UC. Sensitivities of FOBT for positive stool culture in acute diarrhea were 0.38 and 0.87. Sensitivity of FOBT is poor for IDA: 42% of patients with identifiable causes of IDA had false-negative FOBT. Our results did not show acceptable performance characteristics for FOBT to guide decisions regarding endoscopic evaluation and do not support its use in IDA.

False-Positive Results in a Population-Based Colorectal Screening Program: Cumulative Risk from 2000 to 2017 with Biennial Screening.

The aim of this study was to estimate the cumulative risk of a false-positive (FP) result in a fecal occult blood test (FOBT) through 7 screening rounds and to identify its associated factors in a population-based colorectal cancer screening program. Retrospective cohort study, which included participants ages 50 to 69 years of a colorectal cancer screening program in Catalonia, Spain. During this period, 2 FOBTs were used (guaiac and immunochemical). A discrete-time survival model was performed to identify risk factors of receiving a positive FOBT with no high-risk adenoma or colorectal cancer in the follow-up colonoscopy. We estimated the probability of having at least 1 FP over 7 screening rounds. During the period of 2000 to 2017, the cumulative FP risk was 16.3% (IC95%: 14.6%-18.3%), adjusted by age, sex, and type of test. The median number of screens was 2. Participants who began screening at age 50 years had a 7.3% [95% confidence interval (CI), 6.35-8.51] and a 12.4% (95% CI, 11.00-13.94) probability of an FP with 4 screening rounds of guaiac-based test and immunochemical test, respectively. Age, the fecal immunochemical test, first screening, and number of personal screens were factors associated with an FP result among screenees. The cumulative risk of an FP in colorectal screening using FOBT seems acceptable as the colonoscopy, with its high accuracy, lengthens the time until additional colorectal screening is required, while complication rates remain low. It is useful to determine the cumulative FP risk in cancer screening for both advising individuals and for health resources planning.

Comparison of a New-generation Fecal Immunochemical Test (FIT) With Guaiac Fecal Occult Blood Test (gFOBT) in Detecting Colorectal Neoplasia Among Colonoscopy-referral Patients.

The aim of the present study was to compare fecal immunochemical tests (FITs) for colorectal cancer (CRC) screening with the traditional guaiac-based FOB tests (gFOBT). A cohort of 368 colonoscopy-referral patients were evaluated by i) the new-generation FIT: ColonView quick test (CV; Biohit Oyj, Finland) and ii) a conventional gFOBT HemoccultSENSA (HS; Beckman Coulter, USA). Three fecal samples were requested for both assays, and all subjects underwent diagnostic colonoscopy with biopsy confirmation. Sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV) and area under curve (AUC) were calculated for both tests using three endpoints: adenoma (A), advanced adenoma (AA) and adenocarcinoma (AC). Colonoscopy and biopsies disclosed normal mucosa in 90/378 (24.5%) subjects, early A in 108/368 (29.3%) cases, AA in 48/368 (13.0%) and AC in 37/368 (10.1%), and non-neoplastic conditions in the remaining 85 (30.3%). For the AC endpoint, the CV (Hb/Hp) test had 94.6% SE and 65.1% SP (AUC=0.799), while the HS test had SE of 75.7% and SP of 84.3% (AUC=0.800). For the A endpoint, the difference between CV and HS was even more pronounced; SE of 44.2% and 19.2%, respectively (p<0.0001). Hb and Hb/Hp complex of the CV test showed equal performance for all endpoints. Sensitivity (94.6%) of the ColonView quick test for the most reproducible endpoint (invasive CRC) far exceeded the pooled sensitivity (79%) estimated in a recent meta-analysis for 8 common FIT brands. As shown in a previous study, ColonView quick test is superior in SE to HemoccultSENSA test, making CV a perfect FIT for organized CRC screening.

Fecal immunological blood test is more appealing than the guaiac-based test for colorectal cancer screening

BackgroundThe reasons for participation in fecal immunological testing (FIT) of subjects who were previously non-respondents to guaiac fecal occult blood testing (g-FOBT) have not been assessed. Population and methodsWe aimed to determine the reasons for current compliance with FIT among non-responders to g-FOBT, termed “converts‿, in a French district. A questionnaire was returned by 170 converts aged from 55 to 75 years (response rate 75.2% after exclusions). ResultsThe major barriers to participation in screening with g-FOBT were test-related: the test was perceived as complicated (24%) and it required three consecutive stools (28%). Among the test-related major determinants of FIT compliance was the perception that the test was less complicated than previous test (30%) and that a unique stool sample was required (29%). Among the non-test related major determinants of FIT compliance were the perception that the general practitioner was more convincing (31%) and the feeling to be more concerned because of age (21%). The reasons for compliance among converts did not differ according to age, sex, and rural or urban residence. ConclusionsOur study demonstrated that the simplicity of FIT and the endorsement of practitioners were both major motivations for FIT compliance among non-respondents in at least two previous consecutive campaigns.

Colorectal Cancer Screening Programme in Spain: Results of Key Performance Indicators After Five Rounds (2000-2012).

Effective quality assurance is essential in any screening programme. This article provides a unique insight into key quality indicators of five rounds of the first population-based colorectal cancer screening programme implemented in Spain (2000–2012), providing the results according to the type of screening (prevalent or first screen and incident or subsequent screen) and test (guaiac or immunochemical). The total crude participation rate increased from 17.2% (11,011) in the first round to 35.9% (22,988) in the last one. Rescreening rate was very high (88.6% in the fifth round). Positivity rate was superior with the faecal immunochemical test (6.2%) than with the guaiac-based test (0.7%) (p < 0.0001) and detection rates were also better with the immunochemical test. The most significant rise in detection rate was observed for high risk adenoma in men (45.5 per 1,000 screened). Most cancers were diagnosed at an early stage (61.4%) and there was a statistically significant difference between those detected in first or subsequent screening (52.6% and 70.0% respectively; p = 0.024). The availability of these results substantially improves data comparisons and the exchange of experience between screening programmes.

The sensitivity, specificity, predictive values, and likelihood ratios of fecal occult blood test for the detection of colorectal cancer in hospital settings.

ObjectivesTo study the performance of a single test using two fecal occult blood tests with colonoscopy for the detection of colorectal cancer (CRC) for the first time in Saudi Arabia to determine possible implications for the anticipated colorectal screening program.Materials and methodsWe compared the performance of guaiac and immunochemical fecal occult blood tests for the detection of CRC among patients of 50–74 years old attending two hospitals in the Eastern Region of Saudi Arabia. Samples of feces were collected from 257 asymptomatic patients and 20 cases of confirmed CRC, and they were tested simultaneously by the guaiac-based occult blood test and monoclonal antibody-based immunoassay kit. Colonoscopy was performed on all participants and the results were statistically analyzed with both positive and negative occult blood tests of both methods.ResultsOf the 277 subjects, 79 tested positive for occult blood with at least one method. Overall, the number of those with an occult blood-positive result by both tests was 39 (14.1%), while for 198 (71.5%), both tests were negative (P<0.0001); 40 (14.4%) samples showed a discrepant result. Colonoscopy data were obtained for all 277 patients. A total of three invasive cancers were detected among the screening group. Of the three, the guaiac test detected two cases, while the immunochemical test detected three of them. Of the 20 control cases, the guaiac test detected 13 CRC cases (P=0.03), while the immunochemical test detected 16 of them (P<0.0001). The sensitivity of guaiac and immunochemical tests for the detection of CRC in the screening group was 50.00% (95% confidence interval [CI] =6.76–93.24) and 75.00% (95% CI =19.41–99.37), respectively. For comparison, the sensitivity of the guaiac fecal occult blood test for detecting CRC among the control group was 65.00% (95% CI =40.78–84.61) while that of FIT was 80.00% (95% CI =56.34–94.27). The specificity of the guaiac and immunoassay tests was 77.87% (95% CI =72.24–82.83) and 90.12% (95% CI =85.76–93.50), respectively. The positive likelihood ratio of guaiac and immunochemical tests for the detection of CRC was 2.26 (95% CI =0.83–6.18) and 7.59 (95% CI =3.86–14.94), whereas the negative likelihood ratio was 0.64 (95% CI =0.24–1.71) and 0.28 (95% CI =0.05–1.52), respectively. The positive predictive values of guaiac and immunochemical tests were 3.45% (95% CI =0.426–11.91) and 10.71% (95% CI =2.27–28.23), respectively. There was no marked difference in the negative predictive values for both methods. The sensitivity of the fecal occult blood test by FIT was significantly higher for stages III and IV colorectal cancer than for stages I and II (P=0.01) and it was insignificant for the guaiac fecal occult blood test (P=0.07).ConclusionIn areas where other advance screening methods of CRC are not feasible, the use of FIT can be considered.

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.

The Inappropriate Use of Fecal Immunochemical Testing in a Safety-Net Hospital

Introduction: Denver health and hospital, a large safety-net health care system in Colorado with multiple primary care and subspecialty clinics as well as a 500-bed hospital, switched from guaiac-based stool testing as it’s primary stool-based colon cancer screening modality to fecal immunochemical testing (FIT) in 2012. Studies have demonstrated that FIT is a more sensitive and specific test than guaiac-based stool testing. FIT has only been validated as a screening tool for colorectal cancer in average-risk patients. There is no validation of FIT as a test for gastrointestinal bleeding or in patients who are at high risk for colorectal cancer because of family history. This study examined whether FIT was being used appropriately in the Denver health system. Methods: Denver Health uses the Polymedco OC fit-chek brand of FIT tests. Each analyzed FIT test costs the hospital approximately $14. All of the patients who had a FIT test analyzed in the laboratory of Denver health from April 1, 2012 to March 31, 2013 were identified. Demographic information was collected on the patients. Each FIT test was categorized as either being for screening purposes or diagnostic purposes. Results: In the 1-year study period, 7,986 FIT tests were received in the Denver health laboratory. Of these, 2,442 (30.6%) were ordered for diagnostic purposes (query bleeding), 5,544 (69.4%) were ordered for screening purposes, and 363 (4.5%) were unable to be analyzed for various reasons. The mean age of the patients who had the diagnostic tests was 46±19 years, and the mean age of the patients who had the screening tests was 59±8 years. Nearly all of the analyzed diagnostic tests (2,126, 95%) were ordered in the emergency department, the urgent care clinic, or the inpatient setting. Five hundred fifty-five (25%) of the diagnostic tests were positive. These tests have not led to consistent colonoscopic follow-up. Of the analyzed screening tests, 90 (1.7%) were done inappropriately in the emergency room, urgent care clinic, or inpatient setting. Two hundred sixty-four (5%) of the screening tests were done inappropriately in patients 50 years of age and younger. Conclusion: This is one of few studies looking at the use of FIT in an underserved population. Almost 8,000 FIT tests were returned to the Denver health laboratory over a 1-year period. Of the tests, 4.5% were unable to be analyzed despite being returned to the lab. Nearly 2,500 tests were ordered solely to diagnose bleeding. A small percentage of tests were done in patients less than 50 years of age and in an inappropriate hospital-based setting. Overall, 2,706 tests were done for improper reasons at an estimated cost to the institution of $37,884. This data has led Denver health to remove FIT from the emergency room, urgent care, and inpatient settings.

Accuracy of faecal occult blood test and Helicobacter pylori stool antigen test for detection of upper gastrointestinal lesions

ObjectiveHighly sensitive guaiac-based faecal occult blood (Hemoccult SENSA) and Helicobacter pylori stool antigen testing might help detect upper gastrointestinal lesions when appended to a colorectal cancer screening programme with faecal...

Colonoscopy quality assessment in a mass population screening programme based on faecal occult blood test

the success of colorectal cancer (CRC) screening programmes largely depends on the quality of the events, processes and outcomes and therefore, quality assurance of endoscopy is an essential component. The quality indicators for colonoscopy in a screening programme setting are different from those performed in symptomatic people. The objective of this study was to report the main quality indicators of colonoscopies performed after a positive faecal occult blood test (FOBT) in a CRC screening programme in Catalonia. the period of study includes three rounds of the CRC screening programme from June 2006 to July 2013. Two types of FOBT were used: a qualitative biochemical guaiac-based test (gFOBT) and a quantitative immunochemical test (FIT). Quality indicators analysed in this study were compared to recommended colonoscopy standards from the published guidelines. during the study period, 1,806 colonoscopies were performed in 1,691 individuals with a positive FOBT. All indicators were within the standard except waiting time to colonoscopy. Caecal intubation rate was 95.6 % and adequate bowel cleansing 93.6 %. Adenoma detection rate was better using FIT than gFOBT, 30.7 and 3.8 per 1,000 screenees, respectively. Cancer detection rate was also greater using FIT. Nearly 62 % of cancers were diagnosed at an early stage. The overall complication rate was 10.7 ‰. although the majority of results reached the recommended standards, some areas have been identified for quality enhancement. Continuous monitoring of quality indicators is essential for improving the current effectiveness of CRC screening programmes.

Use of Fecal Immunochemical Tests in the Iowa Research Network

Although the fecal immunochemical test (FIT) has recently emerged as an effective and affordable colorectal cancer screening option, many family physician offices continue to use guaiac-based tests. The purpose of this study was to assess the use of FITs in the Iowa Research Network and to assess physicians' knowledge about FITs. A cover letter and questionnaire were faxed twice to the 291 physician members followed up by a mailing. One hundred and seven (37%) questionnaires were returned. Participants' mean age was 55 years with 78 male responders. Fifty-two (49%) of the physician's offices were in a nonmetro area. Fifty-one (49%) reported using guaiac-based tests and 39 (39%) reported using FITs. Many physicians were unsure of the answers for the FIT knowledge questions. FIT use is not widespread in Iowa Research Network physician offices, and not all physicians are aware of the type of fecal occult blood test being conducted in their office.

Fecal Immunochemical Tests for Colorectal Cancer Screening

New fecal occult blood tests have a higher sensitivity and specificity for detection of adenomas and cancer than guaiac-based tests.

Positivity rates and performances of immunochemical faecal occult blood tests at different cut-off levels within a colorectal cancer screening programme

BackgroundImmunochemical faecal occult blood tests have greater sensitivity for colorectal cancer screening than guaiac-based tests; however the number of positive tests required is still under discussion. MethodsA direct comparison of Hemoccult II with two immunochemical quantitative tests (OC-Sensor and FOB-Gold) using a 2-sample strategy was performed in over 30,000 patients undergoing colorectal cancer screening in France. ResultsPositivity ratio between immunochemical tests and Hemoccult II varied between 2.2 (OC-Sensor) and 2.4 (FOB-Gold) for the lowest cut-off value and 1.5–1.4 for the highest cut-off value. The positive predictive value for colorectal cancer was similar for immunochemical tests and Hemoccult II, and significantly higher for immunochemical tests for advanced adenomas. The detection rate of both colorectal cancer and advanced adenomas was higher with immunochemical tests than with Hemoccult II. With the 2-sample strategy and the lowest cut-off value the detection rate of colorectal cancer almost doubled and for advanced adenomas quadrupled. ConclusionFor colorectal cancer screening with immunochemical faecal occult blood tests, an acceptable strategy would be 2-day sampling with at least one positive test at a cut-off between 150 and 200ng/mL (OC-Sensor) and 176 and 234ng/mL (FOB-Gold). Data on the ease of test interpretation and cost-effectiveness now necessary to make definitive choices.

Results of National Colorectal Cancer Screening Program in Croatia (2007-2011)

To study the epidemiologic indicators of uptake and characteristic colonoscopic findings in the Croatian National Colorectal Cancer Screening Program. Colorectal cancer (CRC) was the second leading cause of cancer mortality in men (n = 1063, 49.77/100,000), as well as women (n = 803, 34.89/100,000) in Croatia in 2009. The Croatian National CRC Screening Program was established by the Ministry of Health and Social Welfare, and its implementation started in September, 2007. The coordinators were recruited in each county institute of public health with an obligation to provide fecal occult blood testing (FOBT) to the participants, followed by colonoscopy in all positive cases. The FOBT was performed by hypersensitive guaiac-based Hemognost card test (Biognost, Zagreb). The test and short questionnaire were delivered to the home addresses of all citizens aged 50-74 years consecutively during a 3-year period. Each participant was required to complete the questionnaire and send it together with the stool specimen on three test cards back to the institute for further analysis. About 4% FOBT positive cases are expected in normal risk populations. A descriptive analysis was performed. A total of 1,056,694 individuals (born between 1933-1945 and 1952-1957) were invited to screening by the end of September 2011. In total, 210,239 (19.9%) persons returned the envelope with a completed questionnaire, and 181,102 of them returned it with a correctly placed stool specimen on FOBT cards. Until now, 12,477 (6.9%), FOBT-positive patients have been found, which is at the upper limit of the expected values in European Guidelines for Quality Assurance in CRC Screening and Diagnosis [European Union (EU) Guidelines]. Colonoscopy was performed in 8541 cases (uptake 66%). Screening has identified CRC in 472 patients (5.5% of colonoscopied, 3.8% of FOBT-positive, and 0.26% of all screened individuals). This is also in the expected range according to EU Guidelines. Polyps were found and removed in 3329 (39% of colonoscopied) patients. The largest number of polyps were found in the left half of the colon: 64% (19%, 37% and 8% in the rectum, sigma, and descendens, respectively). The other 36% were detected in the proximal part (17% in the transverse colon and 19% in ceco-ascending colon). Small polyps in the rectum (5-10 mm in diameter), sigmoid and descending colon were histologically found to be tubular adenomas in 60% of cases, with a low degree of dysplasia, and 40% were classified as hyperplastic. Polyps of this size in the transverse or ceco-ascending colon in almost 20% had a histologically villous component, but still had a low degree of dysplasia. Polyps sized 10-20 mm in diameter were in 43% cases tubulovillous, and among them, 32% had areas with a high degree of dysplasia, especially those polyps in the ceco-ascending or transverse part. The characteristics of the Croatian CRC Screening National Program in the first 3 years were as follows: relatively low percentage of returned FOBT, higher number of FOBT-positive persons but still in the range for population-based programs, and higher number of pathologic findings (polyps and cancers). These results suggest a need for intervention strategies that include organizational changes and educational activities to improve awareness of CRC screening usefulness and increase participation rates.

David Reginald Ball

Previous randomized studies suggest that fecal occult blood test (FOBT) screening can reduce mortality from colorectal cancer (CRC). Our aim was to review the current status of FOBTs in CRC...

Analytical Comparison of Three Quantitative Immunochemical Fecal Occult Blood Tests for Colorectal Cancer Screening

The superiority of several immunochemical fecal occult blood tests (I-FOBT) over guaiac-based tests in colorectal cancer screening is now established. The aim of this study was to compare the analytical performance of 3 quantitative I-FOBTs. Stool samples from 10 healthy volunteers, initially I-FOBT negative, supplemented with human blood, were used to compare reproducibility and stability of measurement at varying storage temperatures (4°C, 10°C, 20°C, and 30°C) and durations before test analysis (1 to 10 days) for 3 I-FOBTs (New Hemtube/Magstream HT, OC-Auto sampling bottle3/OC-Sensor DIANA, and FOB Gold/SENTiFOB). Concentrations ranging from 0 to 350 μg Hb/g of feces were evaluated. The measurement reproducibility of OC-Sensor was superior to Magstream and far superior to FOB Gold. For all tests, variability was essentially related to sampling. Detected hemoglobin (Hb) levels were substantially lower for all tests at temperatures above 20°C. At 20°C, this loss in concentration was less important with OC-Sensor (significant 1.7% daily decrease vs. 7.4% for Magstream and 7.8% for FOB Gold). At 30°C, daily loss was 8.6% with OC-Sensor, whereas after 24 hours, only 30% of the original Hb was detected with FOB Gold, compared to 70% with Magstream. No Hb was detected on day 5 for the latter 2 tests. About reproducibility and temperature stability, OC-Sensor performed better than Magstream and far better that FOB Gold. Independently of the chosen test, the delay between sampling and test processing should be reduced, the maximal admissible delay depending on ambient temperature.