Comparison of guaiac-based and quantitative immunochemical fecal occult blood testing in a population at average risk undergoing colorectal cancer screening

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

PURPOSE

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.

METHODS

We used a prospective observational cohort design in a Canadian population eligible for screening. All participants received colonoscopy after performing the occult blood tests.

RESULTS

One thousand seventy-five individuals were enrolled (mean age 56.3 years, 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 67 μg/gram stool as the cut-off (23.2 %: 13.2-33.1). The Magstream HemSp, using a cut-off threshold of 30 μg/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.

CONCLUSION

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.

Prevalence of proximal colon serrated polyps in a population at average risk undergoing screening colonoscopy: a multicenter study

BACKGROUND/AIMS

Proximal serrated polyp (SP) is one of potential explanations for the failure of colonoscopy to prevent all interval cancers. The aims of our study were to determine the prevalence of proximal SP in Korea and to investigate clinical factors associated with the proximal SP detection in average-risk people undergoing screening colonoscopy.

METHODS

We re-analyzed the data of the previous prospective study which included asymptomatic, average-risk people over 45 years of age who underwent screening colonoscopy from four tertiary medical centers in South Korea between December 2007 and November 2008 to compare guaiac-based and quantitative immunochemical fecal occult blood tests. SPs included hyperplastic polyps, sessile serrated adenomas, and traditional serrated adenomas.

RESULTS

A total of 926 subjects were analyzed. Of these, 454 subjects (49.0%) and 356 (38.4%) had a total of 859 polyps and 709 adenomas, respectively. One hundred and ten subjects (11.9%) had a total of 150 SPs and 49 (5.3%) had a total of 60 proximal SPs. In comparison between subjects with and without proximal SP, there were no differences with respect to procedure-related variables including endoscopic training, day of week, time of day, and elapsed time as well as demographic features such as age and sex.

CONCLUSIONS

In average-risk people underwent screening colonoscopy, the prevalence of proximal SP was 5.3% in Korea. There were no significant clinical factors associated with the proximal SP detection.

Pan-Canadian initiatives in colorectal cancer screening: adopting knowledge translation tools to accelerate uptake and impact

BACKGROUND

Despite the positive conclusions of several randomized controlled trials and the publication of national recommendations on colorectal cancer (crc) screening, uptake remained low. The inauguration of the National Colorectal Cancer Screening Network in 2007, the same year that the first screening program was announced in Canada, provided an opportunity for integrated knowledge translation to accelerate the processes of program implementation and screening uptake.

AIM

Two primary aims were identified. The first focused on means to monitor the effects of various implementation plans in delivering high-quality population-based crc screening. The second focused on identifying and addressing knowledge gaps that may impair screening participation.

METHOD

The methods used are described in the context of the knowledge-to-action cycle and demonstrate that the initiative itself dictates the point in the cycle at which to start.

RESULTS

The identified need to monitor various implementation plans resulted in the shared development of a quality determinants document. All programs committed to designing data collection so that core components could be measured and compared; 6 operating programs have conducted the first data collection, which will allow for monitoring and for new knowledge creation as the process develops further. The knowledge gap identification project started with new knowledge creation, which identified a higher-than-expected willingness of Canadians to discuss crc screening with physicians, but a low level of understanding of screening as a wellness-related behaviour. Knowledge translation interventions have been developed with the stakeholders to address those gaps, and ongoing surveys to be carried out later in 2011 will help to gauge progress in the understanding and acceptance of crc screening by the population.

CONCLUSIONS

A national network that engaged all programs, policymakers, experts, and lay representatives successfully used knowledge translation principles to enhance the trajectory of crc screening in Canada.

Immunochemical fecal occult blood testing is equally sensitive for proximal and distal advanced neoplasia

OBJECTIVE

Fecal immunochemical testing (FIT) is increasingly used for colorectal cancer (CRC) screening. We aimed to estimate its diagnostic accuracy in invitational population screening measured against colonoscopy.

METHODS

Participants (50-75 years) in an invitational primary colonoscopy screening program were asked to complete one sample FIT before colonoscopy. We estimated FIT sensitivity, specificity, and predictive values in detecting CRC and advanced neoplasia (carcinomas and advanced adenomas) for cutoff levels of 50 (FIT50), 75 (FIT75), and 100 (FIT100) ng hemoglobin (Hb)/ml, corresponding with, respectively, 10, 15 and 20 μg Hb/g feces.

RESULTS

A total of 1,256 participants underwent a FIT and screening colonoscopy. Advanced neoplasia was detected by colonoscopy in 119 (9%), 8 (0.6%) of them had CRC. At FIT50, 121 (10%) had a positive test result; 45 (37%) had advanced neoplasia and 7 (6%) had CRC. A total of 74 of 1,135 FIT50 negatives (7%) had advanced neoplasia including 1 (0.1%) CRC. FIT50 had a sensitivity of 38% (95% confidence interval (CI): 29-47) for advanced neoplasia and 88% (95% CI: 37-99) for CRC at a specificity of 93% (95% CI: 92-95) and 91% (95% CI: 89-92), respectively. The positive and negative predictive values for FIT50 were 6% (95% CI: 3-12) and almost 100% (95% CI: 99-100) for CRC, and 37% (95% CI: 29-46) and 93% (95% CI: 92-95) for advanced neoplasia. The sensitivity and specificity of FIT75 for advanced neoplasia were 33% (95% CI: 25-42) and 96% (95% CI: 94-97). At FIT100, 71 screenees (6%) had a positive test result. The sensitivity and specificity of FIT100 were for advanced neoplasia 31% (95% CI: 23-40) and 97% (95% CI: 96-98), and for CRC 75% (95% CI: 36-96) and 95% (95% CI: 93-96). The area under curve for detecting advanced neoplasia was 0.70 (95% CI: 0.64-0.76). FIT had a similar sensitivity for proximal and distal advanced neoplasia at cutoffs of 50 (38% vs. 37%; P=0.99), 75 (33% vs. 31%; P=0.85) and 100 (33% vs. 29%; P=0.68) ng Hb/ml.

DISCUSSION

Nine out of ten screening participants with CRC and four out of ten with advanced neoplasia will be detected using one single FIT at low cutoff. Sensitivity in detecting proximal and distal advanced neoplasia is comparable.

Colorectal cancer screening: why immunochemical faecal occult blood test performs as well with either one or two samples

BACKGROUND

Immunochemical faecal occult blood tests perform as well with either one or two samples, and better than guaiac tests with 6 samples.

AIMS

Clarifying relationship between tests' performance, bleeding pattern and observation level.

METHODS

The data of 32,225 average-risk subjects who performed both Hemoccult II (guaiac) and Magstream (immunochemical) tests were re-analysed by varying the cutoff and number of samples of Magstream.

RESULTS

The identical performances obtained using one or two samples of Magstream (lower cutoff for one sample) at the population level were explained by opposite patterns of bleeding according to the presence of advanced neoplasias. They translated into discrepancy at the individual level: for example a 60% increase in sensitivity and 20% in specificity observed with one (39ng Hb/ml cutoff) or two samples (63ng Hb/ml cutoff) Magstream compared with Hemoccult II meant that 28.5% of the subjects testing positive with one sample (18.0% in subjects with advanced neoplasias) would have been considered negative by using two samples of Magstream at a higher cutoff (and reciprocal).

CONCLUSION

The identical performance of immunochemical tests using one or two samples (different cutoff), explained by opposite pattern of bleeding according to advanced neoplasias is true only at the population level, the appropriate level for mass screening.

Role of capsule endoscopy as a screening tool for colorectal cancer

SUMMARY Colon capsule endoscopy is currently under evaluation to become a noninvasive colorectal cancer screening test. The sensitivity and specificity of colon capsule endoscopy for colorectal polyps and cancer are improving with ongoing technical refinements to the capsule and recording device, with sensitivity as high as 84% for polyps greater than 1 mm in size. Specificity for smaller polyps, however, remains suboptimal. Colon capsule endoscopy requires extensive bowel preparation to ensure adequate colon cleansing and complete colonic evaluation. The complication rate for colon capsule endoscopy is unclear, but may be lower than that for small bowel capsule endoscopy. The role of colon capsule endoscopy in colorectal cancer screening has not been fully defined, as technical, logistical and implementation issues remain.

[Korean guidelines for colorectal cancer screening and polyp detection]

Colorectal cancer is the second most common cancer in males and the fourth most common in females in Korea. Since the most of colorectal cancer occur through the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. Korean Multi-Society Take Force developed the guidelines with evidence-based methods. Parts of the statements drawn by systematic reviews and meta-analyses. Herein we discussed the epidemiology of colorectal cancers and adenomas in Korea, optimal screening methods for colorectal cancer, and detection for adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.

Comparison between a guaiac and three immunochemical faecal occult blood tests in screening for colorectal cancer

BACKGROUND

The aim of this study was to compare the performance of the guaiac-based faecal occult blood test (G-FOBT), with that of three immunochemical faecal occult blood tests (I-FOBT) which allow automatic interpretation.

PATIENTS AND METHODS

Under the French organised screening programme, 85,149 average-risk individuals aged 50-74 participating in the third screening round, performed both the G-FOBT (Hemoccult-II test) and one of the I-FOBTs: FOB-Gold, Magstream and OC-Sensor.

RESULTS

Given the chosen threshold, the positivity ratio between the different I-FOBTs and the G-FOBT was 2.4 for FOB-Gold, 2.0 for Magstream and 2.2 for OC-Sensor (P=0.17). The three I-FOBTs were superior to the G-FOBT for colorectal cancer (CRC) detection. The ratios for detection rates were 1.6 (FOB-Gold), 1.7 (Magstream) and 2.1 (OC-Sensor) (P=0.74). For non-invasive CRC they were, respectively, 2.5, 3.0 and 4.0 (P=0.83) and for advanced adenomas 3.6, 3.1 and 4.0 (P=0.39).

CONCLUSIONS

This study provides further evidence that I-FOBT is superior to G-FOBT. None of the three I-FOBTs studied appeared to be significantly better than the others.

Korean guidelines for colorectal cancer screening and polyp detection

Now colorectal cancer is the second most common cancer in males and the fourth most common cancer in females in Korea. Since most of colorectal cancers occur after the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. The guideline was developed by the Korean Multi-Society Take Force and we tried to establish the guideline by evidence-based methods. Parts of the statements were draw by systematic reviews and meta-analyses. Herein we discussed epidemiology of colorectal cancers and adenomas in Korea and optimal methods for screening of colorectal cancer and detection of adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.

Comparison and combination of blood-based inflammatory markers with faecal occult blood tests for non-invasive colorectal cancer screening

Background:

Faecal occult blood tests (FOBTs) are widely used for colorectal cancer (CRC) screening. Blood-based inflammatory markers have been suggested as alternative or supplementary non-invasive CRC screening tests.

Methods:

Among 179 CRC patients, 193 people with advanced adenoma and 225 people free of neoplasm, C-reactive protein (CRP), serum CD26 (sCD26), complement C3a anaphylatoxin and tissue inhibitor of metalloproteinases 1 (TIMP-1) levels in blood were measured by ELISA tests, and an immunochemical FOBT (iFOBT) and a guaiac-based FOBT were performed. Receiver operating characteristic curves were constructed and the areas under the curves (AUCs) were compared.

Results:

The blood levels of CRP, sCD26 and TIMP-1 showed statistically significant differences between CRC patients and neoplasm-free participants, and levels of TIMP-1 were furthermore significantly elevated in advanced adenoma patients. For the four inflammatory markers, AUCs ranged from 0.52 to 0.62 for CRC detection and from 0.50 to 0.58 for advanced adenomas detection, compared with AUCs of 0.90 and 0.68 for the iFOBT. At 97% specificity, blood markers showed much lower sensitivities than FOBTs. Combining inflammatory markers with the iFOBT increased the AUC for advanced adenomas.

Conclusion:

These blood-based markers do not seem to be an alternative to FOBT-based CRC screening. The potential use of these and other blood-based tests in combination with iFOBT might deserve further attention.

Fecal immunochemical tests compared with guaiac fecal occult blood tests for population-based colorectal cancer screening

Colorectal cancer (CRC) is the second most common cause of cancer deaths in Canadian men and women - accounting for almost 12% of all cancer deaths. In Ontario, it is estimated that 8100 persons were diagnosed with CRC in 2011, and 3250 died from the disease. CRC incidence and mortality rates in Ontario are among the highest in the world. Screening offers the best opportunity to reduce this burden of disease. The present report describes the findings and recommendations of Cancer Care Ontario's Fecal Immunochemical Tests (FIT) Guidelines Expert Panel, which was convened in September 2010 by the Program in Evidence-Based Care. The purpose of the present guideline is to evaluate the existing evidence concerning FIT to inform the decision on how to replace the current guaiac fecal occult blood test with FIT in the Ontario ColonCancerCheck Program. Eleven articles were included in the present guideline, comprising two systematic reviews, five articles reporting on three randomized controlled trials, and reports of four other studies. Additionally, one laboratory study was obtained that reported on several parameters of FIT tests that helped to inform the present recommendation. The performance of FIT is superior to the standard guaiac fecal occult blood test in terms of screening participation rates and the detection of CRC and advanced adenoma. Given greater specimen instability with the use of FIT, a pilot study should be undertaken to determine how to implement the FIT in Ontario.

Lower risk of advanced neoplasia among patients with a previous negative result from a fecal test for colorectal cancer

BACKGROUND & AIMS

Consecutive rounds of fecal occult blood tests (FOBTs) are used to screen for colorectal cancer (CRC); they detect precursor lesions and early-stage disease. We assessed whether the positivity rate and the positive predictive values (PPVs) for advanced neoplasia and CRC decrease with repeated testing by using fecal immunochemical tests (FITs).

METHODS

Data were collected from 2 rounds of screening. In the first round, average-risk persons (50 to 74 years old) were randomly assigned to groups that received the guaiac FOBT or FIT. In the second round, the subjects received only FIT (1594 received FIT after guaiac FOBT and 2022 received FIT after FIT). The positivity rate and PPV for advanced neoplasia and CRC were compared between second-round participants with a previous negative test result (FIT after guaiac FOBT or FIT after FIT) and first-round participants (guaiac FOBT or FIT).

RESULTS

The rate of positive results from FIT was 7.4% in the FIT-after-FIT group, compared with 8.1% in the first-round FIT group (P = .34). A significant decrease was observed in the PPV for advanced neoplasia between the first and second round from 55% (132/239) to 44% (112/252; P = .017). The PPV for CRC was 8% (20/239) in the first round versus 4% (9/252) in the second round (P = .024). Ten interval cancers were diagnosed. There were no significant differences in stages of cancers detected in the first and second round or the interval cancers.

CONCLUSIONS

The rate of positive results from FIT does not decrease after repeated CRC screening, but the PPVs of FIT for advanced neoplasia and for CRC are significantly lower among second-round participants who tested negative in the first round.

Discovery and validation of molecular biomarkers for colorectal adenomas and cancer with application to blood testing

Background & Aims

Colorectal cancer incidence and deaths are reduced by the detection and removal of early-stage, treatable neoplasia but we lack proven biomarkers sensitive for both cancer and pre-invasive adenomas. The aims of this study were to determine if adenomas and cancers exhibit characteristic patterns of biomarker expression and to explore whether a tissue-discovered (and validated) biomarker is differentially expressed in the plasma of patients with colorectal adenomas or cancer.

Methods

Candidate RNA biomarkers were identified by oligonucleotide microarray analysis of colorectal specimens (222 normal, 29 adenoma, 161 adenocarcinoma and 50 colitis) and validated in a previously untested cohort of 68 colorectal specimens using a custom-designed oligonucleotide microarray. One validated biomarker, KIAA1199, was assayed using qRT-PCR on plasma extracted RNA from 20 colonoscopy-confirmed healthy controls, 20 patients with adenoma, and 20 with cancer.

Results

Genome-wide analysis uncovered reproducible gene expression signatures for both adenomas and cancers compared to controls. 386/489 (79%) of the adenoma and 439/529 (83%) of the adenocarcinoma biomarkers were validated in independent tissues. We also identified genes differentially expressed in adenomas compared to cancer. KIAA1199 was selected for further analysis based on consistent up-regulation in neoplasia, previous studies and its interest as an uncharacterized gene. Plasma KIAA1199 RNA levels were significantly higher in patients with either cancer or adenoma (31/40) compared to neoplasia-free controls (6/20).

Conclusions

Colorectal neoplasia exhibits characteristic patterns of gene expression. KIAA1199 is differentially expressed in neoplastic tissues and KIAA1199 transcripts are more abundant in the plasma of patients with either cancer or adenoma compared to controls.

Are fecal immunochemical test characteristics influenced by sample return time? A population-based colorectal cancer screening trial

OBJECTIVES

Fecal immunochemical tests (FIT) are preferred over guaiac-based fecal occult blood testing as colorectal cancer (CRC) screening tool. However, hemoglobin (Hb) degradation over time may influence FIT outcome. We therefore evaluated the effect of sample return time on FIT performance characteristics in a population-based CRC screening trial.

METHODS

A representative random sample of the Dutch population (n=17,677), aged 50-74 years, was invited for FIT screening (OC-Sensor Micro; cutoff ≥ 50 ng Hb/ml). Sample return time was defined as the interval in days between fecal sampling and FIT laboratory delivery. Moreover, a random sample of positive FITs were selected to be stored at room temperature and re-tested every 3-4 days.

RESULTS

In total, 8,958 screenees fulfilled our inclusion criteria. The mean sample return time was 3 days (± 3). Overall, 792 screenees (8.8%) had a positive test. Between the sample return time groups, the positivity rate (PR) varied between 7.7 and 9.0%. No statistically significant associations were found between PR or detection rate (DR) and the different sample return time groups (P value=0.84 and 0.76, respectively). For the laboratory experiment, 71 positive FITs were stored at room temperature and re-tested with standard intervals. The mean daily fecal Hb decrease was 5.88% per day (95% confidence interval 4.78-6.96%). None of the positive FITs became negative before 10 days after fecal sampling.

CONCLUSIONS

This population-based CRC screening trial demonstrates that both the PR and DR of FITs do not decrease with prolonged sample return times up to 10 days. This means that a delay in sending the FIT back to the laboratory, of up to at least 1 week, does not necessitate repeat sampling in case of a negative test result. These data support the use of FIT-based screening as a reliable tool for nationwide CRC screening programs.

Editorial: taking FIT to the people: out of the office and into the mail

Colorectal cancer (CRC) screening is most commonly performed in the United States using an opportunistic approach: patients coming to a physician's office for other unrelated reasons are offered screening with either fecal occult blood tests or, more commonly, a referral for colonoscopy. This approach has been effective to a point. CRC screening rates are increasing, but are still suboptimal and vary across different regions of the United States. Mailed fecal immunochemical test (FIT) outreach has the potential to allow more consistent CRC screening, by moving beyond opportunistic, office visit-based screening, to an organized approach. The study by van Roon et al. in this issue of the American Journal of Gastroenterology demonstrates that mailing FIT collection devices will not result in decreased sensitivity for 10-14 days following the specimen collection.

Canadian guidelines for colorectal cancer screening

Decisions regarding colorectal cancer screening will continue to depend on local resources, which in some jurisdictions includes programmatic screening and individual patient preferences. I encourage gastroenterologists to participate in programmatic screening and assist in developing the colonoscopy quality assurance and improvement programs. Our involvement would ensure that we remain leaders in this area and that our expertise in quality in endoscopy is recognized. Finally, participation in programmatic screening should benefit endoscopic services by increasing resources to support higher colonoscopy volumes, shorter wait lists and continuing quality assurance.

Barriers to colorectal cancer screening among publicly insured urban women: no knowledge of tests and no clinician recommendation

OBJECTIVES

To assess barriers to colorectal cancer screening among urban publicly insured women and to evaluate how barriers among underscreened urban women have changed between 2001 and 2007-2008.

METHODS

Eligible women were selected using Medicaid Managed Care Organization (MMCO) administrative data. MMCO outreach staff interviewed women by phone between October 2007 and February 2008, and assessed their barriers to colorectal cancer screening. We compared the results of these interviews with interviews conducted in 2001 with women in community health center waiting rooms.

RESULTS

Thirty percent of overdue women had never heard of either colonoscopy or sigmoidoscopy, and 55% had never heard of home fecal occult blood testing (FOBT). Among overdue women who had heard of colonoscopy or sigmoidoscopy, 33% reported misconceptions and 28% reported worry as a barrier. No clinician recommendation was the most commonly reported barrier to home FOBT (44%) and was also reported as a barrier to endoscopy by 22% of women. Between 2001 and 2007-2008, the proportion of women reporting that they had not received a clinician's recommendation for endoscopy or home FOBT increased significantly.

CONCLUSIONS

A lack of information, no clinician recommendation, misconceptions, and worry persist as barriers to colon cancer screening among this underscreened urban population. An increased focus on clinician recommendation and patient education about stool-based as well as endoscopic screening methods could lead to greater screening compliance.

Is fecal occult blood testing more sensitive for left- versus right-sided colorectal neoplasia? A systematic literature review

Owing to its slow development from removable precursor lesions and early cancer stages with good prognosis, screening for colorectal cancer holds potential to reduce both the incidence and mortality of the disease. While sigmoidoscopy only detects left-sided neoplasia, there is accumulating evidence that colonoscopy is also more effective in protecting from neoplasia in the left versus the right colon and rectum. In this context, it is an important question whether the sensitivity of the most common noninvasive screening tool for colorectal cancer, fecal occult blood testing (FOBT), also differs for left- versus right-sided neoplasia. Therefore, we systematically searched the literature for prospective screening studies conducted in average-risk adults that performed FOBT (immunochemical and/or guaiac-based) and colonoscopy among all participants, and reported site-specific sensitivities of FOBT for advanced colorectal neoplasia. Most of the seven included studies showed a higher sensitivity of FOBT for advanced neoplasia in the left versus right colon, but this finding needs to be confirmed since the available literature is scarce and not entirely consistent.

Double sampling of a faecal immunochemical test is not superior to single sampling for detection of colorectal neoplasia: a colonoscopy controlled prospective cohort study

Background

A single sampled faecal immunochemical test (FIT) has moderate sensitivity for colorectal cancer and advanced adenomas. Repeated FIT sampling could improve test sensitivity. The aim of the present study is to determine whether any of three different strategies of double FIT sampling has a better combination of sensitivity and specificity than single FIT sampling.

Methods

Test performance of single FIT sampling in subjects scheduled for colonoscopy was compared to double FIT sampling intra-individually. Test positivity of double FIT sampling was evaluated in three different ways: 1) "one of two FITs+" when at least one out of two measurements exceeded the cut-off value, 2) "two of two FITs+" when both measurements exceeded the cut-off value, 3) "mean of two FITs+" when the geometric mean of two FITs exceeded the cut-off value. Receiver operator curves were calculated and sensitivity of single and the three strategies of double FIT sampling were compared at a fixed level of specificity.

Results

In 124 of 1096 subjects, screen relevant neoplasia (SRN) were found (i.e. early stage CRC or advanced adenomas). At any cut-off, "two of two FITs+" resulted in the lowest and "one of two FITs+" in the highest sensitivity for SRN (range 35-44% and 42%-54% respectively). ROC's of double FIT sampling were similar to single FIT sampling. At specificities of 85/90/95%, sensitivity of any double FIT sampling strategy did not differ significantly from single FIT (p-values 0.07-1).

Conclusion

At any cut off, "one of two FITs+" is the most sensitive double FIT sampling strategy. However, at a given specificity level, sensitivity of any double FIT sampling strategy for SRN is comparable to single FIT sampling at a different cut-off value. None of the double FIT strategies has a superior combination of sensitivity and specificity over single FIT.

Indirect Comparison of Two Quantitative Immunochemical Faecal Occult Blood Tests in a Population with Average Colorectal Cancer Risk

Magstream and OC Sensor quantitative immunochemical faecal occult blood tests (IFOBT) have shown better performances than guaiac (G) tests in colorectal cancer screening, however Magstream and OC Sensor have never been compared. We hypothesized that similar performances could be observed with Magstream and OC Sensors, provided a similar cut-off (expressed in concentration of haemoglobin in the stools) is used. We performed a literature-based indirect comparison between these tests, taking into account the cut-off, the number of samples, and the way they were combined (I2+: at least one positive sample of 2; I2++: both positive samples; I1: only one sample). Six studies conducted in general average-risk populations were included in this review. For each [test]*[cut-off], positivity rate (PR) decreased and predictive positive value (PPV) increased from I2+ to I1 and I2++. For similar PR, PPV with OC Sensor was greater than with Magstream. This could be due to factors other than the test, because PPVs associated with GFOBT in studies evaluating OC Sensor were greater than PPVs associated with GFOBT in the study evaluating Magstream. Direct comparison between Magstream and OC Sensor is needed to confirm the suspected superiority of OC Sensor.

Organized colorectal cancer screening in integrated health care systems

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

Colonoscopy screening rates among patients of colonoscopy-trained African American primary care physicians

BACKGROUND

When performed competently, colonoscopy screening can reduce colorectal cancer rates, especially in high-risk groups such as African Americans. Training primary care physicians (PCPs) to perform colonoscopy may improve screening rates among underserved high-risk populations.

METHODS

The authors compared colonoscopy screening rates and computed adjusted odds ratios for colonoscopy-eligible patients of trained African American PCPs (study group) versus untrained PCPs (comparison group), before and after initiating colonoscopy training. All colonoscopies were performed at a licensed ambulatory surgery center with specialist standby support. Retrospective chart review was conducted on 200 consecutive, established outpatients aged ≥50 years at each of 12 PCP offices (7 trained African American PCPs and 5 untrained PCPs, practicing in the same geographic region). There were a total of 1244 study group and 923 comparison group patients.

RESULTS

Post-training colonoscopy rates in both groups were higher than pretraining rates: 48.3% versus 9.3% in the study group, 29.6% versus 9.8% in the comparison group (both P < .001). African American patients in the study group showed a >5-fold increase (8.9% pretraining vs 52.8% post-training), with no change among whites (18.2% vs 25.0%). Corresponding pretraining and post-training rates among comparison patients were 10.4%% and 38.7%, respectively, among African Americans (P < .001), and 13.3% versus 13.2%, respectively, among whites. After adjusting for demographics, duration since becoming the PCP's patient, and health insurance, the study group had a 66% higher likelihood of colonoscopy in the post-training period (odds ratio, 1.66; 95% confidence interval, 1.30-2.13), and African Americans had a 5-fold increased likelihood of colonoscopy relative to whites.

CONCLUSIONS

Colonoscopy-trained PCPs may help reduce colorectal cancer disparities.

Diagnostic yield improves with collection of 2 samples in fecal immunochemical test screening without affecting attendance

BACKGROUND & AIMS

The fecal immunochemical test (FIT) is superior to the guaiac-based fecal occult blood test in detecting neoplasia. There are not much data on the optimal number of FITs to perform. We conducted a population-based trial to determine attendance and diagnostic yield of 1- and 2-sample FIT screening.

METHODS

The study included 2 randomly selected groups of subjects aged 50-74 years (1-sample FIT, n=5007; 2-sample FIT, n=3197). The 2-sample group was instructed to collect fecal samples on 2 consecutive days. Subjects were referred for colonoscopy when at least 1 sample tested positive (≥50 ng hemoglobin/mL).

RESULTS

Attendance was 61.5% in the 1-sample group (2979 of 4845; 95% confidence interval, 60.1%-62.9%) and 61.3% in the 2-sample group (1875 of 3061; 95% confidence interval, 59.6%-63.0%; P=.84). In the 1-sample group 8.1% tested positive, and in the 2-sample group 12.8% had at least 1 positive test outcome and 5.0% had 2 positive test outcomes (P<.05). When the mean from both test results in the 2-sample group was used, 10.1% had a positive test outcome (P<.05). The detection rates for advanced neoplasia were 3.1% in the 1-sample group, 4.1% in the 2-sample group with at least 1 positive test outcome, 2.5% when both test results were positive, and 3.7% among subjects with the mean from both test results being positive.

CONCLUSIONS

There is no difference in attendance for subjects offered 1- or 2-sample FIT screening. The results allow for the development of efficient FIT screening strategies that can be adapted for local colonoscopy capacities, rather than varying the cut-off value in a 1-sample strategy.

Reduction of novel circulating long-chain fatty acids in colorectal cancer patients is independent of tumor burden and correlates with age

BACKGROUND

Serum levels of novel hydroxy polyunsaturated ultra long-chain fatty acids (hPULCFAs) have been previously shown to be reduced in pre-treatment CRC patients compared to disease-free subjects, independent of disease stage. However, whether reduced levels of hPULCFAs result from the presence of cancer is currently unknown, as is the distribution of hPULCFAs in the general population. The following studies were carried out to assess whether conventional therapy would result in restoration of systemic hPULCFAs in CRC patients, and to investigate the relationship between hPULCFA levels and age.

METHODS

Tandem mass spectrometry was used to determine serum levels of the 28 carbon-containing hPULCFA C28H46O4 (CRC-446) in the following cohorts: two independent Japanese CRC populations following surgical tumor removal (n = 86), a North American Caucasian CRC cohort (n = 150) following post-surgery combination chemo/radiation therapy, 990 randomly selected anonymized serum samples from subjects ranging between 11 and 99 years of age, as well as longitudinally collected serum samples from healthy normals (n = 8, up to 90 weeks) and stage IV CRC subjects on combination therapy (n = 12, up to 63 weeks).

RESULTS

Serum CRC-446 levels in CRC subjects were significantly lower than controls (mean of 0.297 ± 0.07 ug/ml in controls versus 0.092 ± 0.03 in CRCs, p < 0.001), and were unaffected by surgical tumor removal or by chemo/radiation treatment (p > 0.05 between pre vs post surgery). CRC-446 levels showed a strong inverse association with age (p < E-11) across the randomly-selected cohort of 990 subjects, with no correlation observed in the CRC-positive subjects. Longitudinal intra-subject results, however, showed relatively stable CRC-446 levels over the short term of up to 90 weeks in both disease-free subjects and late-stage CRC patients.

CONCLUSIONS

Our findings show that CRC-446 levels are not affected by conventional CRC treatment and inversely correlate with age, which suggest that reduced serum CRC-446 levels likely exist prior to the development of CRC. Extrapolation of the results to a simple screening scenario showed that, compared to fecal blood testing, pre-colonoscopy screening using serum CRC-446 levels would require 80% fewer colonoscopies, would identify risk in subjects under the age of 50, and would result in increased numbers of early cases detected. The precise role these serum metabolites play in the aetiology of cancer development remains to be determined.