Guaiac-based Fecal Occult Blood Test Research Articles

Well adjusted qualitative immunochemical faecal occult blood tests could be a promising alternative for inexpensive, high-quality colorectal cancer screening

Immunochemical faecal occult blood tests (iFOBTs) have been shown to have higher sensitivity to detect colorectal cancer (CRC) and its precursors than traditional guaiac-based faecal occult blood tests, but are more costly and require specific laboratory equipment. A number of qualitative iFOBTs have been developed, but their performance varied widely because of the large variation in positivity thresholds used for test positivity. We aimed to evaluate the performance of qualitative iFOBTs with well adjusted positivity thresholds in the screening setting. In a study of 229 participants who underwent screening colonoscopy in Germany (45 patients with CRC, 65 with advanced adenoma and 119 free of colorectal neoplasms), we evaluated the performance of two qualitative iFOBTs at five different positivity thresholds and compared it with the performance of a quantitative iFOBT. Receiver operating characteristic curves were constructed. The areas under the curve, and the sensitivity and specificity of the tests, were calculated. For both qualitative tests, sensitivities were around 30% for advanced adenoma and 80% for CRC at very high levels of specificity (98-99%). Comparison of results with the receiver operating characteristic curves for the quantitative test indicated that the qualitative tests yielded similarly high levels of sensitivity at comparable levels of specificity. In conclusion, with appropriate adjustment of positivity thresholds ensuring the levels of specificity required in population-based screening, qualitative, office-based iFOBTs can be an economic, qualitatively comparable alternative to quantitative iFOBTs.

Colorectal cancer screening with fecal occult blood test: A 22-year cohort study.

The aim of the present study was to investigate the efficacy of colorectal cancer (CRC) screening with a three-tier fecal occult blood test (FOBT) in the Chinese population. The study was performed between 1987 and 2008 at the Beijing Military General Hospital, in a cohort of army service males and females aged >50 years. Between 1987 and 2005, a three-tier screening program, comprising guaiac-based FOBTs (gFOBTs), followed by immunochemical FOBTs for positive guaiac test samples and then colonoscopy for positive immunochemical test subjects, was performed annually. The cohort was followed up until 2008. The cohort included 5,104 subjects, of which, 3,863 subjects participated in screening (screening group) and 1,241 did not (non-screening group). The two groups did not differ in age, gender or other major risk factors for colon cancer. Overall, 36 CRCs occurred in the screening group and 21 in the non-screening group. Compared with the non-screening group, the relative risk for the incidence and mortality of CRC was 0.51 [95% confidence interval (CI), 0.30–0.87] and 0.36 (95% CI, 0.18–0.71), respectively, in the screening group. The general sensitivity of this three-tier FOBT was 80.6% (95% CI, 65.3–91.1). Thus, annual screening using the three-tier FOBT program may reduce the CRC incidence and mortality rate.

Finding the Best FIT for Colorectal Cancer Screening

Experts widely agree that a fecal immunochemical test (FIT) should replace a guaiac-based fecal occult blood test for colorectal cancer (CRC) screening

PWE-020 Do Seasonal Trends in Positivity Exist with the Guaiac-Based Faecal Occult Blood Test?

IntroductionSeveral bowel cancer screening programmes, including the NHS Bowel Cancer Screening Programme (BCSP) in England, use a guaiac-based faecal occult blood test (gFOBt). Seasonal variations in gFOBt positivity have been...

Clinical outcomes using a faecal immunochemical test for haemoglobin as a first-line test in a national programme constrained by colonoscopy capacity.

Because of their many advantages, faecal immunochemical tests (FIT) are superseding traditional guaiac-based faecal occult blood tests in bowel screening programmes. A quantitative FIT was adopted for use in two evaluation National Health Service (NHS) Boards in Scotland using a cut-off faecal haemoglobin concentration chosen to give a positivity rate equivalent to that achieved in the Scottish Bowel Screening Programme. Uptake and clinical outcomes were compared with results obtained contemporaneously in two other similar NHS Boards and before and after the evaluation in the two evaluation NHS Boards. During the evaluation, uptake was 58.5%. This was higher than in the same NHS Boards both before and after the evaluation, higher than in the other two NHS Boards and higher than the 53.7% achieved overall in Scotland. The overall positivity rate was higher in men than in women and increased with age in both genders. Positive predictive values for cancer (4.8%), high-risk adenoma (23.3%), all adenoma (38.2%) and all neoplasia (43.0%) in the two test NHS Boards were similar in all groups. In summary, this evaluation of the FIT supports the introduction of FIT as a first-line test, even when colonoscopy capacity is limited.

PWE-021 An Investigation into High Gfobt Positivity During the First Five Days following sample Collection

IntroductionThe NHS Bowel Cancer Screening Programme (BCSP) in England has used the guaiac-based faecal occult blood test (gFOBt) since 2006. Test positivity is higher during the first 5 days after...

Mo1191 An Investigation of High gFOBT Positivity During the First Five Days Following Sample Collection

Introduction The NHS Bowel Cancer Screening Programme (BCSP) in England has used the guaiac-based faecal occult blood test (gFOBt) since 2006. Test positivity is higher during the first 5 days after sample collection. Methods The gFOBt kits used by the BCSP have six windows (three pairs) lined with guaiac-impregnated philtre paper. The screening participant is asked to apply two faecal samples from three separate stools. The samples usually arrive dry at the laboratory, which is likely to reduce the degree of haemoglobin (Hb) degradation and provide the best opportunity to detect bleeding. BCSP policy is that every kit is logged on the day of receipt and read as soon as possible thereafter. BCSP Southern Hub data from the Bowel Cancer Screening System (BCSS) for 01/2008–07/2012 were analysed for subjects aged 60–69 years completing the first prevalent round of screening. The interval between each sample date and the date the sample was analysed (elapsed time) was calculated. Spot positivity was assessed by elapsed time, stratified by sex. Clinical outcomes were extracted from BCSS for subjects who had a positive gFOBt result. The relationship between positivity, elapsed time and clinical outcomes was examined. Results During the period of observation, nearly 1.2 million kits were returned to the Hub and 92% were read within five days of the last sample collection. For samples analysed one day after the last sample collection, spot positivity was 2.7% for women and 3.8% for men. Positivity declined thereafter until it reached a steady level at day 5 (women 1.3%; men 2.0%). Positivity for the most recently collected sample (usually spots 5 and 6) was slightly higher than for the spots collected earlier. There were 20,408 subjects (8,343 women; 12,065 men) who accepted further investigation. The outcome of those investigations was not associated with elapsed time between faecal sampling and test kit reading; the proportion of cancers, high-, intermediate- and low-risk adenomas was fairly constant as elapsed time increased. Conclusion The higher positivity associated with a shorter elapsed time did not appear to be associated with more false-positive tests. A number of factors may contribute to the pattern of positivity observed: (a) vegetable peroxidases present in the diet cause short term increases in gFOBt positivity; (b) faecal Hb denatures gradually before analysis, and (c) screening invitees worried about their health may return test kits more rapidly than others and a proportion of those individuals will be found to have colorectal cancer and related disease. None of those factors alone can account for the marked elevation in the ‘early positivity rate’ and further studies are required to elucidate the reasons for this effect. Disclosure of Interest None Declared.

Mo1192 Impact of Incidental Findings of 18 FDG-PET/CT in the Patients With Gastric Cancer

Background The NHS Bowel Cancer Screening Programme (BCSP) in England has used the guaiac-based faecal occult blood test (gFOBt) since 2006. The kits have six windows (three pairs) lined with guaiac-impregnated filter paper to which two faecal samples from three consecutive stools are applied. The samples usually arrive dry at the laboratory, which is likely to reduce the degree of haemoglobin (Hb) degradation and provide the best opportunity to detect bleeding. The amount of bleeding from bowel cancer lesions and adenomas is directly related to the degree of bowel pathology. BCSP policy is that every kit is logged on the day of receipt and read as soon as possible thereafter. Test positivity is higher during the first 5 days after sample collection, but the reasons for this are unclear. Vegetable peroxidases in the diet and their rapid degradation in faeces is one possible explanation. Method BCSP Southern Hub data from the Bowel Cancer Screening System for 01/200807/2012 were analysed for subjects aged 60-69 years completing the first prevalent round of screening. The interval between each sample date and the date the sample was analysed (elapsed time) was calculated. Spot positivity was assessed by elapsed time, stratified by sex. Clinical outcomes were extracted from BCSS for subjects who had a positive gFOBt result. The relationship between positivity, elapsed time and clinical outcomes was examined. Results Overall, 92% of test kits were read in the Hub within 5 days of the last sample collection. For samples analysed one day after the last sample collection, spot positivity was 2.7% for women and 3.8% for men. Positivity declined thereafter until it reached a steady level at day 5 (women 1.3%; men 2.0%). Positivity for the most recently collected sample (spots 5 and 6) was slightly higher than for the spots collected earlier. There were 20,408 subjects (8,343 women; 12,065 men) referred for further investigation after gFOBt testing during the study period. The outcome of those further investigations was not associated with elapsed time between faecal sampling and test kit reading; the proportion of cancers, high-, intermediate and low-risk adenomas was fairly constant as elapsed time increased. Conclusions The higher positivity associated with a shorter elapsed time is not associated with a higher proportion of false-positive tests. There is the possibility that the fairly constant yield of false and true positives over time could reflect a balance between vegetable peroxidase degradation and the degradation of Hb associated with various degrees of pathology. Conversely, the higher positivity during the first few days after sample collection might be explained simply by the possibility that worried (perhaps symptomatic) individuals may return the test kit for analysis more quickly. Further work is required to confirm these observations.

Using resource modelling to inform decision making and service planning: the case of colorectal cancer screening in Ireland

BackgroundOrganised colorectal cancer screening is likely to be cost-effective, but cost-effectiveness results alone may not help policy makers to make decisions about programme feasibility or service providers to plan programme delivery. For these purposes, estimates of the impact on the health services of actually introducing screening in the target population would be helpful. However, these types of analyses are rarely reported. As an illustration of such an approach, we estimated annual health service resource requirements and health outcomes over the first decade of a population-based colorectal cancer screening programme in Ireland.MethodsA Markov state-transition model of colorectal neoplasia natural history was used. Three core screening scenarios were considered: (a) flexible sigmoidoscopy (FSIG) once at age 60, (b) biennial guaiac-based faecal occult blood tests (gFOBT) at 55–74 years, and (c) biennial faecal immunochemical tests (FIT) at 55–74 years. Three alternative FIT roll-out scenarios were also investigated relating to age-restricted screening (55–64 years) and staggered age-based roll-out across the 55–74 age group. Parameter estimates were derived from literature review, existing screening programmes, and expert opinion. Results were expressed in relation to the 2008 population (4.4 million people, of whom 700,800 were aged 55–74).ResultsFIT-based screening would deliver the greatest health benefits, averting 164 colorectal cancer cases and 272 deaths in year 10 of the programme. Capacity would be required for 11,095-14,820 diagnostic and surveillance colonoscopies annually, compared to 381–1,053 with FSIG-based, and 967–1,300 with gFOBT-based, screening. With FIT, in year 10, these colonoscopies would result in 62 hospital admissions for abdominal bleeding, 27 bowel perforations and one death. Resource requirements for pathology, diagnostic radiology, radiotherapy and colorectal resection were highest for FIT. Estimates depended on screening uptake. Alternative FIT roll-out scenarios had lower resource requirements.ConclusionsWhile FIT-based screening would quite quickly generate attractive health outcomes, it has heavy resource requirements. These could impact on the feasibility of a programme based on this screening modality. Staggered age-based roll-out would allow time to increase endoscopy capacity to meet programme requirements. Resource modelling of this type complements conventional cost-effectiveness analyses and can help inform policy making and service planning.

Harms of colonoscopy in a colorectal cancer screening programme with faecal occult blood test: A population-based cohort study

To assess the harms of colonoscopy in a real world colorectal cancer screening programme with faecal occult blood test. Retrospective cohort study of all colonoscopies performed in patients aged 50-74 for a positive guaiac-based faecal occult blood test between September 2003 and February 2010 within the screening programme in progress in Alsace (France). Adverse events were recorded through prospective voluntary reporting by gastroenterologists and retrospective postal surveys addressed to persons screened and their general practitioners. Of 10,277 colonoscopies, 250 adverse events were recorded, 48 (4.7 ‰, 95% CI 3.4-6.0) of them being moderate or severe, mainly 10 (1.0 ‰, 95% CI 0.4-1.6) perforations and 31 (3.0 ‰, 95% CI 2.0-4.1) bleeding. 91.7% of moderate and severe adverse events were the result of a therapeutic procedure. Of 103 serious adverse events, eight (7.8%) were considered preventable. Gastroenterologists reported 52.2% of moderate and severe adverse events. A mild adverse event or an incident was reported in up to 97.0 ‰ (95% CI 83.2-110.7) colonoscopies. The harms of colonoscopy were underestimated in all randomized controlled trials on colorectal cancer screening with faecal occult blood test. They are greater in a real world programme, estimated at 7.5 major and 100 minor adverse events per 1000 colonoscopies.

Critical considerations of fecal occult blood tests for colorectal cancer

1University of Dundee, Nethergate, Dundee, DD1 4HN, Scotland, UK *Author for correspondence: r.j.c.steele@dundee.ac.uk The most commonly used strategy in colo­ rectal cancer (CRC) screening pro grams involves the use of stool tests to detect occult blood, and guaiac fecal occult blood tests (gFOBTs) are, to date, the only fecal tests shown to reduce CRC mortality in population­based randomized trials [1]. However, gFOBTs also carry disadvantages. A major concern is that interval cancers account for around 50% of cancers detected in gFOBT screened populations [2] and recent data show that gFOBTs are less sensitive in women than in men, and in both rectal and right­sided cancers when compared with left­sided disease [2,3]. In addition, the test is associated with a high false­positive rate with no neoplasia detected in around half of colonoscopies performed following a positive gFOBT [2,3]. This may be, in part, explained by the fact that gFOBTs are not specific for human hemoglobin (Hb) and are subject to possible dietary interference from, for example, red meat and high­peroxidase fruits and vegetables. As a result, it has been common practice to instruct participants to adhere to dietary restrictions ahead of sample collection, although this may act as a barrier to screening and affect participation rates [4]. However, data from a meta­analysis did not support dietary restrictions with gFOBTs, leading to recommendations that restrictions are abandoned to improve adherence rates [5]. Fecal immunochemical tests (FITs) are now available and are increasingly being used in screening programs. Unlike gFOBTs, FITs are specific for the detection of human Hb, eliminating any potential for dietary interference, and are also more specific than gFOBT for lower gastrointestinal bleeding. In addition, modern FITs generally allow a more convenient method of sample collection, and are associated with better participation rates [6]. Another major advantage of FIT is that automated versions not only eliminate interobserver variability, but also the quantitative nature of these tests allow provision of a measured fecal Hb concentration. Screening program “...the adoption of fecal immunochemical tests in colorectal cancer screening programs has potential to address participation, appropriate positivity rates and the problem of false‐negative results.” EDITORIAL

Cost-effectiveness of population-based screening for colorectal cancer

Cost-effectiveness of population-based screening for colorectal cancer

Commentary: adherence and detection rates in colorectal cancer screening

Sirs, I read with interest the meta-analysis comparing immunochemical faecal occult blood test (FIT), guaiac-based faecal occult blood test (g-FOBT) and endoscopy in the detection rate for advanced neoplasia as well as the uptake to screening.1 Certainly CRC screening remains a very much debated issue at the moment, not just in the more established countries but also in the developing world where it is just a matter of time before CRC screening takes off on a large scale. The study addressed two very relevant questions comparing the two main methods of population screening at present. Hassan et al. found that perhaps not surprisingly, faecal occult blood tests have a higher rate of adherence compared with endoscopy; [optical colonoscopy(OC) and flexible sigmoidoscopy(FS)]. It would certainly be ideal to have more data comparing FS and OC, particularly if FS becomes more available in an out-patient setting. The most interesting finding was that endoscopy was superior in detecting advanced neoplasia even in an intention-to-treat (ITT) basis, i.e. taking into account the whole targeted population. This is presumably due to the false-negative rate of faecal occult blood tests and the low uptake of follow-up endoscopy in positive cases. Despite these findings, many other considerations are to be taken into account when considering a large population-based screening program. The cost effectiveness of each strategy remains difficult to determine.2 As the studies in the meta-analysis were mainly in Western countries, the findings may not necessarily apply to other populations. Availability of endoscopy is a significant problem in the developing world. A study is underway comparing the Asia-Pacific Colorectal Screening score3 and FIT in the detection of advanced neoplasia. It would certainly be ideal if we could identify and target at risk individuals without an excessive endoscopic burden or the large scale use of FIT. Declaration of personal and funding interests: None.

Fecal Immunochemical Testing for Colorectal Cancer Screening

Fecal immunochemical testing (FIT) might be more accurate than guaiac-based fecal occult blood testing (gFOBT) in screening for colorectal cancer. In

Yield of Fecal Immunochemical Test in Detection of Colorectal Cancer and Advanced Neoplasia in Veteran Population at Dayton VA Medical Center

Purpose: Fecal occult blood test (FOBT) is a widely accepted, non-invasive technique for colorectal cancer (CRC) screening. According to national VA directive, a diagnostic colonoscopy must be performed within 60 days of the positive FOBT test. Since May 2009, the Dayton VAMC has replaced the guaiac-based fecal occult blood test (gFOBT) with fecal immunochemical test (FIT) using a cut-off of 100 mg/ml hemoglobin. Aim: To compare the yield of gFOBT versus FIT in the detection of CRC and advanced neoplasia (AN) in average risk veterans at Dayton VAMC and to determine compliance with a follow-up colonoscopy within 60 days of a positive test. Methods: We performed a retrospective chart review of all patients referred for follow-up colonoscopy after a positive FOBT screening test at Dayton VAMC between February 2008 and September 2010. Results: During the study period a total of 351 FOBT (171 gFOBT and 180 FIT) positive subjects were referred for colonoscopy. A total of 65% (229/351) patients completed a colonoscopy, 71% (122/171) with positive gFOBT and 59% (107/180) with positive FIT. Median interval between positive FOBT and colonoscopy was 74 days (Range 1-846 days). Colonoscopy was completed within 60 and 90 days of a positive test in 28% (65/229) and 66% (152/229) subjects, respectively. There were 96% males with median age of 62 years (Range 38-90 years) at the time of positive FOBT. Positive colonoscopy findings (hemorrhoids, diverticuli, polyps, AVMs, mass, inflammation, ischemia) noted in 80% (97/122) gFOBT vs. 88% (94/107) FIT group (p=0.11). The prevalence of AN was 19% (23/122) in gFOBT vs. 23% (25/107) in FIT group. Prevalence of AN in single positive gFOBT was 12% (8/69) vs. 13% (8/61) in FIT group. AN in gFOBT group was located proximal and distal to the splenic flexure in 22% (5/23) and 35% (8/23), respectively. In FIT group, AN was located proximal and distal to the splenic flexure in 12% (3/25) and 32% (8/25), respectively. Synchronous proximal and distal AN was noted in 44% (10/23) gFOBT vs. 56% (14/25) FIT group. CRC was diagnosed in 4% (8/229) patients with median age of 72 years (Range: 55-85 years) at diagnosis. Six cancers were distal and two proximal to the splenic flexure. Prevalence of invasive CRC was 5% (6/122) in gFOBT vs. 2% (2/107) in FIT group (p=0.28). Prevalence of adenomas 10 mm or more in size was 27% (17/63) in gFOBT vs. 35% (21/60) in FIT group (p=0.44). Conclusion: The prevalence of AN was higher in the FIT compared to the gFOBT group, possibly indicating that the FIT test might be more sensitive for detecting earlier stages of neoplasia. Less than one third of the subjects completed a colonoscopy within 60 days of a positive test, indicating need to improve compliance with follow-up colonoscopy.

Detection of Methylated SEPT9 in Plasma Is a Reliable Screening Method for Both Left- and Right-Sided Colon Cancers

BackgroundMethylated Septin 9 (SEPT9) is a sensitive biomarker for colorectal cancer (CRC) from peripheral blood. However, its relationship to cancer localization, guaiac-based fecal occult blood test (gFOBT) and carcinoembryonic antigen (CEA) have not been described.Methodology/Principal FindingsPlasma samples were collected for SEPT9 analysis from patients with no evidence of disease (NED) (n = 92) before colonoscopy and CRC (n = 92) before surgical treatment. DNA was isolated and bisulfite-converted using Epi proColon kit 2.0. Qualitative determination was performed using Epi proColon 2.0 RT-PCR assay. Samples for gFOBT and CEA analysis were collected from NED (n = 17 and 27, respectively) and CRC (n = 22 and 27, respectively). SEPT9 test was positive in 15.2% (14/92) of NED and 95.6% (88/92) of CRC, including 100% (67/67) from stage II to stage IV CRC and 84% (21/25) of stage I CRC when a sample was called positive if 1 out of 3 PCR replicates was positive. In a second analysis (2 out of 3 PCR replicates) specificity improved to 99% (91/92) of NEDs, at a sensitivity of 79.3% (73/92) of SEPT9 positives in CRC. gFOBT was positive in 29.4% (5/17) of NED and 68.2% (15/22) of CRC and elevated CEA levels were detected in 14.8% (4/27) of NED and 51.8% (14/27) of CRC. Both SEPT9 (84.8%) and CEA (85.2%) showed higher specificity than gFOBT (70.6%). SEPT9 was positive in 96.4% (54/56) of left-sided colon cancer (LSCC) cases and 94.4% (34/36) of right-sided colon cancer (RSCC) cases. gFOBT was positive in 83.3% (10/12) of cases with LSCC and 50% (5/10) of cases with RSCC, elevated CEA was detected 60% (9/15) of LSCC and 41.7% (5/12) of RSCC.Conclusions/SignificanceThe high degree of sensitivity and specificity of SEPT9 in plasma makes it a better method to detect CRC than gFOBT and CEA, even for the more difficult to detect RSCC.

A future for faecal haemoglobin measurements in the medical laboratory

Guaiac-based faecal occult blood tests (gFOBT) are still used in asymptomatic population bowel screening programmes but are being replaced by faecal immunochemical tests (FIT) for haemoglobin. gFOBT have many well-documented disadvantages and there is little evidence for their use in assessment of the symptomatic. Many laboratories have eliminated gFOBT from their approved repertoires by invoking the authoritative published guidelines. Data continue to accumulate that gFOBT are obsolete. FIT are available in two formats, qualitative and quantitative, the latter having advantages that the faecal haemoglobin concentrations are measured and cut-off concentrations that stimulate further investigation can be user-defined. There is growing evidence that FIT would be useful in a spectrum of clinical settings in addition to screening. All laboratories should have FIT in their existing repertoire. For some uses, qualitative FIT would be adequate. However, much evidence has accumulated that measurements of faecal haemoglobin concentrations are beneficial for the assessment of both disease severity and the future risk of colorectal neoplasia. Interpretation requires appreciation that faecal haemoglobin concentrations are higher in men than women and rise with age. It might well be that risk scoring systems that take gender and age into account, possibly with other factors including symptoms, will benefit individuals. Laboratories should consider how quantitative faecal haemoglobin measurements could be brought into routine practice and included in their forward planning. External quality assessment is needed. Specialists in laboratory medicine are urged to play a significant role in the research and development still required to make this a truly mature investigation.

Effect of season and ambient temperature on outcome of guaiac-based faecal occult blood tests performed for colorectal cancer screening

Guaiac-based faecal occult blood tests (gFOBTs) are used in the colorectal cancer screening programme. Recent data suggested that the immunological faecal occult blood test illustrated a variation in positivity according to season and ambient temperature. Our aim was to assess the effect of season and ambient temperature on the positivity rates of the gFOBT during pilot screening for colorectal cancer. Data from the first year of round 1 of the pilot screening programme in Coventry and Warwickshire were analysed. Patients with positive and negative gFOBT samples were included. Patients with spoilt samples or incomplete data were excluded. Of the total of 59513 patients, 30311 were men and 29202 women. Mean age was 56 years. Daily temperature data were provided by the meteorological office. Median exposure of the gFOBT test card was 6 days (range 1-17). Median daily maximum temperature was 14°C. Spring and summer illustrated significantly decreased positivity rates compared with autumn and winter (Pearson's chi-squared test, P<0.001). Mean daily maximum temperature for the test card exposure showed no significant difference in positivity rates (P=0.53). Subgroup analysis revealed a significant reduction in positive samples in the >25°C subgroup (P=0.045). There is a seasonal variation in positivity rates of gFOBTs with increased positivity in spring and summer months. There is no difference in positivity rates in relation to ambient temperature except in subgroup analysis where there is a significant reduction in positivity rates above 25°C.

Challenges and opportunities: putting into practice research-tested approaches to increase colorectal cancer screening

189 ISSN 1758-194X 10.2217/CRC.12.26 © 2012 Future Medicine Ltd Colorect. Cancer (2012) 1(3), 189–192 1Fox Chase Cancer Center, 510 Township Line Road, Cheltenham, PA 19012, USA 2Division of Population Science, Department of Medical Oncology, 1025 Walnut Street, Suite 1014 College Bldg, Thomas Jefferson University, Philadelphia, PA 19107, USA 3Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA *Author for correspondence: Tel.: +1 215 728 3690; Fax: +1 215 379 1369; linda.fleisher@fccc.edu Colorectal cancer (CRC) is the third most common form of cancer in the USA among men and women, with approximately 141,210 new cases diagnosed and 49,380 deaths annually [101]. The American Cancer Society (ACS) and the United States Preventive Services Task Force (USPSTF) encourage screening for adults aged 50 years and older [101]. Numerous screening modalities currently exist, including fecal occult blood testing (FOBT), barium enema (BE), flexible sigmoidoscopy (FS) and colonoscopy. Recognizing the potential contribution that screening can play in reducing the burden of CRC, Healthy People 2020 has called for CRC screening rates to exceed 70%. When CRC is identified in its early stages, survival rates are significantly improved, with 5-year survival rates of stage I patients of up to 74% versus only 6% for those with stage IV disease [101]. While CRC screening rates are rising in the USA, they are still well below the target and lag far behind screening rates for breast and cervical cancers. Furthermore, there is a substantial and persistent CRC screening disparity that contributes to d ifferential mortality and survival. The ACS has separated CRC screening tests into two categories: first, “tests that primarily detect cancer, which include both guaiac-based FOBT (gFOBT) and immunochemical-based FOBT (FIT) and testing stool for exfoliated DNA (sDNA)”; and second, “tests that can detect cancer and advanced lesions, which include endoscopic examinations and radiologic examinations (i.e., flexible sigmoidoscopy [FSIG], colonoscopy, double-contrast barium enema [DCBE], and computed tomography [CT] colonography, or virtual colonoscopy)” [1]. This distinction can help patients and providers make informed decisions after weighing the pros and cons of the tests in each category. It is important to note that the priority is to prevent CRC, and any of these recommended tests are acceptable, although the “We must take advantage of and integrate the many proven approaches to help patients learn about the importance of colorectal cancer screening, understand their options and be motivated to participate.” EDITORIAL

The sensitivity and specificity of guaiac and immunochemical fecal occult blood tests for the detection of advanced colonic adenomas and cancer

Fecal immunochemical tests (FITs) have been developed to address analytical problems inherent in the older guaiac-based fecal occult blood tests (g-FOBTs). Our aim was to compare the performance characteristics of one g-FOBT (Hemoccult II) and two FITs (the Hemoccult ICT and MagStream HemSp) relative to colonoscopy for the detection of colorectal cancer and significant precursor lesions. We also examined whether a 1-day collection strategy would negatively impact test diagnostic performance. We used a prospective observational cohort design in a Canadian population eligible for screening. All participants received colonoscopy after performing the occult blood tests. One thousand seventy-five individuals were enrolled (mean age 56.3years, 53.8% females). Using colonoscopy as the gold standard, the sensitivity for screen-relevant neoplasm was determined for Hemoccult II (7.2, 95% CI: 1.1-13.4), Hemoccult ICT (23.2%: 13.2-33.1), and MagStream HemSp using 67μg/gram stool as the cut-off (23.2%: 13.2-33.1). The Magstream HemSp, using a cut-off threshold of 30μg/gram stool, had the lowest specificity at 87.6% (85.4-89.6), while the Hemoccult II had the highest at 98.8% (98.1-99.5). Single-day stool testing reduced the false-positive rates of all tests without significantly reducing the sensitivity. We found that FITs have a significantly increased sensitivity but reduced specificity for screen-relevant neoplasm compared to g-FOBT using colonoscopy as the gold standard. Optimal threshold levels for hemoglobin detection depend on the desired trade off between sensitivity and false-positive rate. Single-day testing with an FIT may be an option to enhance population compliance with screening.