Immunochemical faecal occult blood tests are superior to guaiac-based tests for the detection of colorectal neoplasms

Effect of fecal immunochemical test cut-off levels on adenoma detection rate: a systematic review and meta-analysis

BACKGROUND

Adenoma detection rate (ADR) is higher after a positive fecal immunochemical test (FIT) compared to direct screening colonoscopy.

OBJECTIVE

This meta-analysis evaluated how ADR, the rates of advanced adenoma detection (AADR), colorectal cancer detection (CDR), and sessile serrated lesion detection (SSLDR) are affected by different FIT positivity thresholds.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and EBM Reviews databases for studies reporting ADR, AADR, CDR, and SSLDR according to different FIT cut-off values in asymptomatic average-risk individuals aged 50-74 years old. Data were stratified according to sex, age, time to colonoscopy, publication year, continent, and FIT kit type. Study quality, heterogeneity, and publication bias were assessed.

RESULTS

Overall, 4280 articles were retrieved and fifty-eight studies were included (277,661 FIT-positive colonoscopies; mean cecal intubation 96.3%; mean age 60.8 years; male 52.1%). Mean ADR was 56.1% (95% CI 53.4 - 58.7%), while mean AADR, CDR, and SSLDR were 27.2% (95% CI 24.4 - 30.1%), 5.3% (95% CI 4.7 - 6.0%), and 3.0% (95% CI 1.7 - 4.6%), respectively. For each 20 μg Hb/g increase in FIT cut-off level, ADR increased by 1.54% (95% CI 0.52 - 2.56%, p < 0.01), AADR by 3.90% (95% CI 2.76 - 5.05%, p < 0.01) and CDR by 1.46% (95% CI 0.66 - 2.24%, p < 0.01). Many detection rates were greater amongst males and Europeans.

CONCLUSIONS

ADRs in FIT-positive colonoscopies are influenced by the adopted FIT positivity threshold, and identified targets, importantly, proved to be higher than most current societal recommendations.

Impact of colorectal cancer screening on incidence, mortality and surgery rates: Evidences from programs based on the fecal immunochemical test in Italy

Fecal immunochemical tests (FIT) are among the most commonly used tests for colorectal cancer (CRC) screening programs worldwide. However, no randomised controlled trials have been carried out evaluating the impact of FIT-based screening programs (FIT-progr) on CRC incidence and mortality rates. Italian FIT-progr represent one of the most widespread and established experience worldwide. This paper reviews the evidence on the impact of FIT-progr on CRC incidence, tumor stage at diagnosis, mortality and surgery rates, deriving from Italian routine programs, i.e., outside the research setting. Unfortunately, the application of FIT-progr in Italy can be considered as an unplanned experimental model, due to the differences between Regions, both in health system management and adherence of the target population to the screening programs. The analysis of the manuscripts considered in the review, confirms that FIT-progr are effective in reducing CRC incidence and mortality rates and in improving the rate of endoscopic treatment of early invasive lesions. The review also highlights that FIT-progr are less performing for proximal colon than for distal colon and rectum.

Clinical Effectiveness of Faecal Immunochemical Test in the Early Detection of Colorectal Cancer-An Umbrella Review

Introduction: The colorectal cancer prognosis depends on the stage of the neoplasm; therefore, its early detection plays an important role. The aim of the study is evaluation of the sensitivity, specificity, and clinical effectiveness of the faecal immunochemical test in the early colorectal cancer detection. Methods: The clinical analysis was based on the results of the studies included in a systematic review conducted in accordance with the Cochrane Collaboration guidelines. The following medical information sources were searched: Medline (via PubMed), Embase (via Ovid), The Cochrane Library. Results: From 241 citations, 13 studies were included in this review. All included studies had a low risk of bias. The faecal immunochemical test is highly specific in all analysed populations ranging from 85% to 97%. In most of the found studies, sensitivity is over 75%. The faecal immunochemical test screening also determines a reduction in death (10-59%) due to colorectal cancer. Conclusions: The faecal immunochemical test is an effective and cost-effective method of conducting population-wide colorectal cancer screening. It is an alternative or complementary to other screening tests, including colonoscopy.

Pooled rates of adenoma detection by colonoscopy in asymptomatic average-risk individuals with positive fecal immunochemical test: a systematic review and meta-analysis

BACKGROUND AND AIMS

Current adenoma detection rate (ADR) benchmarks for colonoscopy in individuals positive for a fecal immunochemical test (FIT) are ≥45% in men and ≥35% in women. These are based on weak, low-quality evidence. We performed a meta-analysis to ascertain the pooled ADR in FIT-positive colonoscopy.

METHODS

Major databases like PubMed, EMBASE, and Web of Science were searched in October 2021 for studies reporting on ADR of colonoscopy in a FIT-positive population. Meta-analysis was performed by standard methodology using the random-effects model. Heterogeneity was assessed by I² and 95% prediction interval statistics.

RESULTS

Thirty-four high-quality studies that included more than 6 million asymptomatic average-risk individuals were analyzed; 2,655,345 individuals completed a screening FIT test. The pooled FIT screening rate was 69.8% (95% CI, 62.8-76.1), the pooled FIT positivity rate was 5.4% (95% CI, 4.3-6.9), and the colonoscopy completion rate was 85% (95% CI, 82.8-86.9). The pooled ADR was 47.8% (95% CI, 44.1-51.6), pooled advanced ADR was 25.3% (95% CI, 22-29), and the pooled colorectal cancer detection rate was 5.1% (95% CI, 4.4-5.9). The pooled ADR in men was 58.3% (95% CI, 52.8-63.6) and in women was 41.9% (95% CI, 36.4-47.6). The pooled ADR with qualitative FIT assessment was 67.7% (95% CI, 50.7-81), with 1-stool sample FIT was 52.8% (95% CI, 48.8-56.8), and at a cutoff threshold of 100 ng hemoglobin/mL was 52.1% (95% CI, 47-57.1). Based on time-period cumulative analysis, the ADR improved over time from 30.5% (95% CI, 24.6-37.2) to 47.8% (95% CI, 44.1-51.6).

CONCLUSIONS

This meta-analysis supports the current ADR benchmarks for colonoscopy in FIT-positive individuals. Excellent pooled ADR parameters were demonstrated with qualitative assessment of 1 stool sample at a test cutoff value of 100 ng hemoglobin/mL, and ADR per endoscopist improved over time.

Guaiac-based faecal occult blood tests versus faecal immunochemical tests for colorectal cancer screening in average-risk individuals

BACKGROUND

Worldwide, many countries have adopted colorectal cancer (CRC) screening programmes, often based on faecal occult blood tests (FOBTs). CRC screening aims to detect advanced neoplasia (AN), which is defined as CRC or advanced adenomas. FOBTs fall into two categories based on detection technique and the detected blood component: qualitative guaiac-based FOBTs (gFOBTs) and faecal immunochemical tests (FITs), which can be qualitative and quantitative. Screening with gFOBTs reduces CRC-related mortality.

OBJECTIVES

To compare the diagnostic test accuracy of gFOBT and FIT screening for detecting advanced colorectal neoplasia in average-risk individuals.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, BIOSIS Citation Index, Science Citation Index Expanded, and Google Scholar. We searched the reference lists and PubMed-related articles of included studies to identify additional studies.

SELECTION CRITERIA

We included prospective and retrospective studies that provided the number of true positives, false positives, false negatives, and true negatives for gFOBTs, FITs, or both, with colonoscopy as reference standard. We excluded case-control studies. We included studies in which all participants underwent both index test and reference standard ("reference standard: all"), and studies in which only participants with a positive index test underwent the reference standard while participants with a negative test were followed for at least one year for development of interval carcinomas ("reference standard: positive"). The target population consisted of asymptomatic, average-risk individuals undergoing CRC screening. The target conditions were CRC and advanced neoplasia (advanced adenomas and CRC combined).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and selected studies for inclusion. In case of disagreement, a third review author made the final decision. We used the Rutter and Gatsonis hierarchical summary receiver operating characteristic model to explore differences between tests and identify potential sources of heterogeneity, and the bivariate hierarchical model to estimate sensitivity and specificity at common thresholds: 10 µg haemoglobin (Hb)/g faeces and 20 µg Hb/g faeces. We performed indirect comparisons of the accuracy of the two tests and direct comparisons when both index tests were evaluated in the same population.

MAIN RESULTS

We ran the initial search on 25 June 2019, which yielded 63 studies for inclusion. We ran a top-up search on 14 September 2021, which yielded one potentially eligible study, currently awaiting classification. We included a total of 33 "reference standard: all" published articles involving 104,640 participants. Six studies evaluated only gFOBTs, 23 studies evaluated only FITs, and four studies included both gFOBTs and FITs. The cut-off for positivity of FITs varied between 2.4 μg and 50 µg Hb/g faeces. For each Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 domain, we assessed risk of bias as high in less than 20% of studies. The summary curve showed that FITs had a higher discriminative ability than gFOBTs for AN (P < 0.001) and CRC (P = 0.004). For the detection of AN, the summary sensitivity of gFOBTs was 15% (95% confidence interval (CI) 12% to 20%), which was significantly lower than FITs at both 10 μg and 20 μg Hb/g cut-offs with summary sensitivities of 33% (95% CI 27% to 40%; P < 0.001) and 26% (95% CI 21% to 31%, P = 0.002), respectively. Results were simulated in a hypothetical cohort of 10,000 screening participants with 1% CRC prevalence and 10% AN prevalence. Out of 1000 participants with AN, gFOBTs missed 850, while FITs missed 670 (10 μg Hb/g cut-off) and 740 (20 μg Hb/g cut-off). No significant differences in summary specificity for AN detection were found between gFOBTs (94%; 95% CI 92% to 96%), and FITs at 10 μg Hb/g cut-off (93%; 95% CI 90% to 95%) and at 20 μg Hb/g cut-off (97%; 95% CI 95% to 98%). So, among 9000 participants without AN, 540 were offered (unnecessary) colonoscopy with gFOBTs compared to 630 (10 μg Hb/g) and 270 (20 μg Hb/g) with FITs. Similarly, for the detection of CRC, the summary sensitivity of gFOBTs, 39% (95% CI 25% to 55%), was significantly lower than FITs at 10 μg and 20 μg Hb/g cut-offs: 76% (95% CI 57% to 88%: P = 0.001) and 65% (95% CI 46% to 80%; P = 0.035), respectively. So, out of 100 participants with CRC, gFOBTs missed 61, and FITs missed 24 (10 μg Hb/g) and 35 (20 μg Hb/g). No significant differences in summary specificity for CRC were found between gFOBTs (94%; 95% CI 91% to 96%), and FITs at the 10 μg Hb/g cut-off (94%; 95% CI 87% to 97%) and 20 μg Hb/g cut-off (96%; 95% CI 91% to 98%). So, out of 9900 participants without CRC, 594 were offered (unnecessary) colonoscopy with gFOBTs versus 594 (10 μg Hb/g) and 396 (20 μg Hb/g) with FITs. In five studies that compared FITs and gFOBTs in the same population, FITs showed a higher discriminative ability for AN than gFOBTs (P = 0.003). We included a total of 30 "reference standard: positive" studies involving 3,664,934 participants. Of these, eight were gFOBT-only studies, 18 were FIT-only studies, and four studies combined both gFOBTs and FITs. The cut-off for positivity of FITs varied between 5 µg to 250 µg Hb/g faeces. For each QUADAS-2 domain, we assessed risk of bias as high in less than 20% of studies. The summary curve showed that FITs had a higher discriminative ability for detecting CRC than gFOBTs (P < 0.001). The summary sensitivity for CRC of gFOBTs, 59% (95% CI 55% to 64%), was significantly lower than FITs at the 10 μg Hb/g cut-off, 89% (95% CI 80% to 95%; P < 0.001) and the 20 μg Hb/g cut-off, 89% (95% CI 85% to 92%; P < 0.001). So, in the hypothetical cohort with 100 participants with CRC, gFOBTs missed 41, while FITs missed 11 (10 μg Hb/g) and 11 (20 μg Hb/g). The summary specificity of gFOBTs was 98% (95% CI 98% to 99%), which was higher than FITs at both 10 μg and 20 μg Hb/g cut-offs: 94% (95% CI 92% to 95%; P < 0.001) and 95% (95% CI 94% to 96%; P < 0.001), respectively. So, out of 9900 participants without CRC, 198 were offered (unnecessary) colonoscopy with gFOBTs compared to 594 (10 μg Hb/g) and 495 (20 μg Hb/g) with FITs. At a specificity of 90% and 95%, FITs had a higher sensitivity than gFOBTs.

AUTHORS' CONCLUSIONS

FITs are superior to gFOBTs in detecting AN and CRC in average-risk individuals. Specificity of both tests was similar in "reference standard: all" studies, whereas specificity was significantly higher for gFOBTs than FITs in "reference standard: positive" studies. However, at pre-specified specificities, the sensitivity of FITs was significantly higher than gFOBTs.

Colonoscopy-Related Adverse Events in Patients With Abnormal Stool-Based Tests: A Systematic Review of Literature and Meta-analysis of Outcomes

INTRODUCTION

Colorectal cancer (CRC) screening programs based on the fecal immunochemical test (FIT) and guaiac-based fecal occult blood (gFOBT) are associated with a substantial reduction in CRC incidence and mortality. We conducted a systematic review and comprehensive meta-analysis to evaluate colonoscopy-related adverse events in individuals with a positive FIT or gFOBT.

METHODS

A systematic and detailed search was run in January 2021, with the assistance of a medical librarian for studies reporting on colonoscopy-related adverse events as part of organized CRC screening programs. Meta-analysis was performed using the random-effects model, and the results were expressed for pooled proportions along with relevant 95% confidence intervals (CIs).

RESULTS

A total of 771,730 colonoscopies were performed in patients undergoing CRC screening using either gFOBT or FIT across 31 studies. The overall pooled incidence of severe adverse events in the entire patient cohort was 0.42% (CI 0.20-0.64); I2 = 38.76%. In patients with abnormal gFOBT, the incidence was 0.2% (CI 0.1-0.3); I2 = 24.6%, and in patients with a positive FIT, it was 0.4% (CI 0.2-0.7); I2 = 48.89%. The overall pooled incidence of perforation, bleeding, and death was 0.13% (CI 0.09-0.21); I2 = 22.84%, 0.3% (CI 0.2-0.4); I2 = 35.58%, and 0.01% (CI 0.00-0.01); I2 = 33.21%, respectively.

DISCUSSION

Our analysis shows that in colonoscopies performed after abnormal stool-based testing, the overall risk of severe adverse events, perforation, bleeding, and death is minimal.

Screening for Colorectal Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Colorectal cancer (CRC) remains a significant cause of morbidity and mortality in the US.

OBJECTIVE

To systematically review the effectiveness, test accuracy, and harms of screening for CRC to inform the US Preventive Services Task Force.

DATA SOURCES

MEDLINE, PubMed, and the Cochrane Central Register of Controlled Trials for relevant studies published from January 1, 2015, to December 4, 2019; surveillance through March 26, 2021.

STUDY SELECTION

English-language studies conducted in asymptomatic populations at general risk of CRC.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently appraised the articles and extracted relevant study data from fair- or good-quality studies. Random-effects meta-analyses were conducted.

MAIN OUTCOMES AND MEASURES

Colorectal cancer incidence and mortality, test accuracy in detecting cancers or adenomas, and serious adverse events.

RESULTS

The review included 33 studies (n = 10 776 276) on the effectiveness of screening, 59 (n = 3 491 045) on the test performance of screening tests, and 131 (n = 26 987 366) on the harms of screening. In randomized clinical trials (4 trials, n = 458 002), intention to screen with 1- or 2-time flexible sigmoidoscopy vs no screening was associated with a decrease in CRC-specific mortality (incidence rate ratio, 0.74 [95% CI, 0.68-0.80]). Annual or biennial guaiac fecal occult blood test (gFOBT) vs no screening (5 trials, n = 419 966) was associated with a reduction of CRC-specific mortality after 2 to 9 rounds of screening (relative risk at 19.5 years, 0.91 [95% CI, 0.84-0.98]; relative risk at 30 years, 0.78 [95% CI, 0.65-0.93]). In observational studies, receipt of screening colonoscopy (2 studies, n = 436 927) or fecal immunochemical test (FIT) (1 study, n = 5.4 million) vs no screening was associated with lower risk of CRC incidence or mortality. Nine studies (n = 6497) evaluated the test accuracy of screening computed tomography (CT) colonography, 4 of which also reported the test accuracy of colonoscopy; pooled sensitivity to detect adenomas 6 mm or larger was similar between CT colonography with bowel prep (0.86) and colonoscopy (0.89). In pooled values, commonly evaluated FITs (14 studies, n = 45 403) (sensitivity, 0.74; specificity, 0.94) and stool DNA with FIT (4 studies, n = 12 424) (sensitivity, 0.93; specificity, 0.85) performed better than high-sensitivity gFOBT (2 studies, n = 3503) (sensitivity, 0.50-0.75; specificity, 0.96-0.98) to detect cancers. Serious harms of screening colonoscopy included perforations (3.1/10 000 procedures) and major bleeding (14.6/10 000 procedures). CT colonography may have harms resulting from low-dose ionizing radiation. It is unclear if detection of extracolonic findings on CT colonography is a net benefit or harm.

CONCLUSIONS AND RELEVANCE

There are several options to screen for colorectal cancer, each with a different level of evidence demonstrating its ability to reduce cancer mortality, its ability to detect cancer or precursor lesions, and its risk of harms.

PPV and Detection Rate of mt-sDNA Testing, FIT, and CT Colonography for Advanced Neoplasia: A Hierarchic Bayesian Meta-Analysis of the Noninvasive Colorectal Screening Tests

BACKGROUND. Noninvasive tests for colorectal cancer (CRC) screening and prevention limit the need for invasive colonoscopy to follow up positive test results. However, the relative performance characteristics of available noninvasive tests have not yet been adequately compared. OBJECTIVE. We performed a systematic review and meta-analysis to compare the diagnostic performance of the available noninvasive CRC screening tests, including multitarget stool DNA (mt-sDNA) testing, fecal immunochemical testing (FIT), and CT colonography (CTC), with an emphasis on comparison of PPV and detection rate (DR) for advanced neoplasia (AN; encompassing cases of advanced adenomas and CRC). EVIDENCE ACQUISITION. After systematic searches of MEDLINE and Google Scholar databases, 10 mt-sDNA, 27 CTC, and 88 FIT published screening studies involving 25,132, 33,493, and 2,355,958 asymptomatic adults, respectively, were included. Meta-analysis with hierarchic Bayesian modeling was conducted in accordance with Cochrane Collaboration and PRISMA guidelines to determine test positivity rates (TPRs) leading to optical colonoscopy, as well as PPVs and DRs for both AN and CRC. Different positivity thresholds were considered for FIT and CTC. EVIDENCE SYNTHESIS. Point estimates (with 95% credible intervals) from pooled Bayesian meta-analysis combining all thresholds for FIT and stratifying CTC results by a polyp size threshold of 6 mm or larger (CTC6) and 10 mm or larger (CTC10) were calculated. TPR was 13.5% (10.9-16.6%) for mt-sDNA testing, 6.4% (5.8-7.2%) for FIT, 13.4% (11.4-15.6%) for CTC6, and 6.6% (5.2-7.7%) for CTC10. AN PPV was 26.9% (95% credible interval, 21.8-33.2%) for mt-sDNA testing, 31.8% (29.3-34.5%) for FIT, 34.4% (27.2-41.0%) for CTC6, and 61.0% (54.0-70.0%) for CTC10. CRC PPV was 2.4% (1.5-3.9%) for mt-sDNA testing, 4.9% (4.3-5.3%) for FIT, 3.5% (2.5-4.8%) for CTC6, and 6.0% (4.3-8.0%) for CTC10. The DR for AN was 3.4% (95% credible interval, 2.5-4.8%) for mt-SDNA, 2.0% (1.8-2.3%) for FIT, 4.8% (4.0-6.5%) for CTC6, and 4.0% (3.0-4.6%) for CTC10. When FIT is restricted to a lower threshold (< 10 μg Hb/g feces), its performance profile is similar to that of mt-sDNA testing, although available data are limited. AN PPV odds ratios (relative to CTC10 as the reference) were 0.24 (95% credible interval, 0.17-0.33) for mt-sDNA testing, 0.30 (0.24-0.45) for FIT, and 0.33 (0.25-0.47) for CTC6. CONCLUSION. Among noninvasive CRC screening tests, CTC with a polyp size threshold of 10 mm or larger most effectively targets AN, preserving detection while also decreasing unnecessary colonoscopies compared with mt-sDNA testing and FIT. CLINICAL IMPACT. CTC performed with a polyp size threshold for colonoscopy referral set at 10 mm or larger represents the most effective and efficient noninvasive screening test for CRC prevention and detection.

Long-term risk of colorectal cancer after screen-detected adenoma: Experiences from a Danish gFOBT-positive screening cohort

Fecal occult blood test (FOBT) screening for colorectal cancer (CRC) is implemented in several countries. Approximately half of all FOBT-positive persons have screen-detected adenomas. Despite removal of these, patients with large/multiple adenomas have increased risk of later developing new advanced adenomas and CRC. International guidelines exist for colonoscopic surveillance following adenoma removal. These divide patients into low-, intermediate- and high-risk groups. We followed 711 FOBT-positive patients with screening adenoma identified during population-based CRC screening in two Danish counties in 2005-2006. As reference population, we included 1,240,348 persons in the same age group from the rest of Denmark not included in the screening. We estimated the long-term CRC risk stratified by adenoma findings during screening and compared to the reference group. After 12 years follow-up, the CRC incidence among all adenoma patients was 322 cases per 100,000 person-years (95% confidence interval [CI]: 212-489) ranging from 251 (95% CI: 94-671) to 542 (95% CI: 300-978) cases per 100,000 person-years in the low- and high-risk groups, respectively. In the reference population, the CRC incidence was 244 (95% CI: 242-247) per 100,000. Patients with screen-detected high-risk adenomas after a positive FOBT had an almost doubled risk of CRC compared to the reference population (adjusted hazard ratio [aHR] 1.95, 95% CI: 1.08-3.51), and the incidence in those with no follow-up visits was over 3.6 (aHR 3.64, 95% CI: 1.82-7.29) times the incidence in the reference population. The increased CRC risk could be controlled if high-risk patients underwent follow-up colonoscopy (aHR 0.87, 95% CI: 0.28-2.69).

Development and validation of a prediction rule for estimating gastric cancer risk in the Chinese high-risk population: a nationwide multicentre study

OBJECTIVE

To develop a gastric cancer (GC) risk prediction rule as an initial prescreening tool to identify individuals with a high risk prior to gastroscopy.

DESIGN

This was a nationwide multicentre cross-sectional study. Individuals aged 40-80 years who went to hospitals for a GC screening gastroscopy were recruited. Serum pepsinogen (PG) I, PG II, gastrin-17 (G-17) and anti-Helicobacter pylori IgG antibody concentrations were tested prior to endoscopy. Eligible participants (n=14 929) were randomly assigned into the derivation and validation cohorts, with a ratio of 2:1. Risk factors for GC were identified by univariate and multivariate analyses and an optimal prediction rule was then settled.

RESULTS

The novel GC risk prediction rule comprised seven variables (age, sex, PG I/II ratio, G-17 level, H. pylori infection, pickled food and fried food), with scores ranging from 0 to 25. The observed prevalence rates of GC in the derivation cohort at low-risk (≤11), medium-risk (12-16) or high-risk (17-25) group were 1.2%, 4.4% and 12.3%, respectively (p<0.001).When gastroscopy was used for individuals with medium risk and high risk, 70.8% of total GC cases and 70.3% of early GC cases were detected. While endoscopy requirements could be reduced by 66.7% according to the low-risk proportion. The prediction rule owns a good discrimination, with an area under curve of 0.76, or calibration (p<0.001).

CONCLUSIONS

The developed and validated prediction rule showed good performance on identifying individuals at a higher risk in a Chinese high-risk population. Future studies are needed to validate its efficacy in a larger population.

Low participation in organized colorectal cancer screening in France: underlying ethical issues

International studies have shown a significant reduction in colorectal cancer (CRC) mortality following the implementation of organized screening programs, given a sufficient participation rate and adequate follow-up. The French national CRC screening program has been generalized since 2008 and targets 18 million men and women aged 50-74 years. Despite broad recommendations, the participation rate remains low (29.8%), questioning the efficiency of the program. A panel of experts was appointed by the French National Cancer Institute to critically examine the place of autonomy and efficiency in CRC screening and propose recommendations. In this paper, we explore the ethical significance of a public health intervention that falls short of its objectives owing to low take-up by the population targeted. First, we analyze the reasons for the low CRC screening participation. Second, we examine the models that can be proposed for public health actions, reconciling respect for the individual and the collective good. Our expert panel explored possible ways to enhance take-up of CRC screening within the bounds of individual autonomy, adapting awareness campaigns, and new educational approaches that take into account knowledge and analysis of sociocultural hurdles. Although public health actions must be universal, target actions should nonetheless be developed for nonparticipating population subgroups.

Time to fecal immunochemical test completion for colorectal cancer screening

OBJECTIVES

Fecal immunochemical tests (FITs) can efficiently screen for colorectal cancer (CRC), but little is known on the timing to their completion. We investigate the time to return of a FIT following an order and describe patient characteristics associated with FIT return.

STUDY DESIGN

Retrospective cohort study.

METHODS

We identified 63,478 members of Kaiser Permanente Washington, aged 50 to 74 years, who received a FIT order from 2011 through 2012. Patient characteristics were ascertained through administrative and electronic health record data sources. We compared time from FIT order to return by patient characteristics using Kaplan-Meier and Cox regression methods.

RESULTS

About half (53.7%) of members completed a FIT. Median time from order to return was 13 days (mean, 44.5 days; interquartile range, 6-42 days). There was higher completion of FITs among Asian patients (hazard ratio [HR], 1.43; 95% CI, 1.38-1.48), black patients (HR, 1.13; 95% CI, 1.08-1.19), and Hispanic patients (HR, 1.10; 95% CI, 1.04-1.16) compared with white patients; among patients with recent CRC testing (vs no testing in past 2 years; HR, 1.90; 95% CI, 1.86-1.95); and among patients with Medicare insurance (vs commercial; HR, 1.30; 95% CI, 1.24-1.37). Factors associated with decreased FIT completion included younger age (50-54 years vs 70-74 years; HR, 0.87; 95% CI, 0.82-0.92), obesity (vs normal body mass index; HR, 0.88; 95% CI, 0.86-0.91), and higher Charlson Comorbidity Index score (≥3 vs 0; HR, 0.82; 95% CI, 0.79-0.87).

CONCLUSIONS

Time to return of FIT varies by patient characteristics. We observed greater FIT completion among people of color, suggesting that racial disparities in CRC may not be due to patient completion of the test after an order is received.

Progress of colorectal cancer screening in United States: Past achievements and future challenges

The United States has seen progress with colorectal cancer with both falling incidence and mortality rates. Factoring into this decline, the significance of early detection and removal of precancerous lesions through screening must be underscored. With the advancement of screening modalities, attention has been directed towards optimizing the quality of screening and detecting adenomas. Colorectal cancer screening has been a major agenda item for national gastroenterology societies, culminating in a major victory with passage of the Balanced Budget Act that allowed for Medicare coverage of colorectal cancer screening. Colonoscopy as the primary screening modality was solidified in the 1990s after landmark studies demonstrated its superiority over modalities for detecting precancerous polyps. Despite progress, colorectal cancer screening disparities between race and gender continue to exist. Legislative efforts are on-going and include the SCREEN Act and Dent Act that aim to further improve access to screening. The National Colorectal Cancer Roundtable has launched colorectal cancer screening initiatives targeting at risk populations. Today, the current goal of these initiatives is to reach colorectal screening rate of 80% of eligible patients by 2018. With these initiatives, efforts to narrow the gaps in screening disparities and lower overall mortality have been prioritized and continued by the medical community. This review article details colorectal cancer screening progress to date and highlights major studies and initiatives that have solidified its success in the United States.

Faecal immunochemical tests versus colonoscopy for post-polypectomy surveillance: an accuracy, acceptability and economic study

BACKGROUND

In the UK, patients with one or two adenomas, of which at least one is ≥ 10 mm in size, or three or four small adenomas, are deemed to be at intermediate risk of colorectal cancer (CRC) and referred for surveillance colonoscopy 3 years post polypectomy. However, colonoscopy is costly, can cause discomfort and carries a small risk of complications.

OBJECTIVES

To determine whether or not annual faecal immunochemical tests (FITs) are effective, acceptable and cost saving compared with colonoscopy surveillance for detecting CRC and advanced adenomas (AAs).

DESIGN

Diagnostic accuracy study with health psychology assessment and economic evaluation.

SETTING

Participants were recruited from 30 January 2012 to 30 December 2013 within the Bowel Cancer Screening Programme in England.

PARTICIPANTS

Men and women, aged 60-72 years, deemed to be at intermediate risk of CRC following adenoma removal after a positive guaiac faecal occult blood test were invited to participate. Invitees who consented and returned an analysable FIT were included.

INTERVENTION

We offered participants quantitative FITs at 1, 2 and 3 years post polypectomy. Participants testing positive with any FIT were referred for colonoscopy and not offered further FITs. Participants testing negative were offered colonoscopy at 3 years post polypectomy. Acceptibility of FIT was assessed using discussion groups, questionnaires and interviews.

MAIN OUTCOME MEASURES

The primary outcome was 3-year sensitivity of an annual FIT versus colonoscopy at 3 years for detecting advanced colorectal neoplasia (ACN) (CRC and/or AA). Secondary outcomes included participants' surveillance preferences, and the incremental costs and cost-effectiveness of FIT versus colonoscopy surveillance.

RESULTS

Of 8008 invitees, 5946 (74.3%) consented and returned a round 1 FIT. FIT uptake in rounds 2 and 3 was 97.2% and 96.9%, respectively. With a threshold of 40 µg of haemoglobin (Hb)/g faeces (hereafter referred to as µg/g), positivity was 5.8% in round 1, declining to 4.1% in round 3. Over three rounds, 69.2% (18/26) of participants with CRC, 34.3% (152/443) with AAs and 35.6% (165/463) with ACN tested positive at 40 µg/g. Sensitivity for CRC and AAs increased, whereas specificity decreased, with lower thresholds and multiple rounds. At 40 µg/g, sensitivity and specificity of the first FIT for CRC were 30.8% and 93.9%, respectively. The programme sensitivity and specificity of three rounds at 10 µg/g were 84.6% and 70.8%, respectively. Participants' preferred surveillance strategy was 3-yearly colonoscopy plus annual FITs (57.9%), followed by annual FITs with colonoscopy in positive cases (31.5%). FIT with colonoscopy in positive cases was cheaper than 3-yearly colonoscopy (£2,633,382), varying from £485,236 (40 µg/g) to £956,602 (10 µg/g). Over 3 years, FIT surveillance could miss 291 AAs and eight CRCs using a threshold of 40 µg/g, or 189 AAs and four CRCs using a threshold of 10 µg/g.

CONCLUSIONS

Annual low-threshold FIT with colonoscopy in positive cases achieved high sensitivity for CRC and would be cost saving compared with 3-yearly colonoscopy. However, at higher thresholds, this strategy could miss 15-30% of CRCs and 40-70% of AAs. Most participants preferred annual FITs plus 3-yearly colonoscopy. Further research is needed to define a clear role for FITs in surveillance.

FUTURE WORK

Evaluate the impact of ACN missed by FITs on quality-adjusted life-years.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN18040196.

FUNDING

National Institute for Health Research (NIHR) Health Technology Assessment programme, NIHR Imperial Biomedical Research Centre and the Bobby Moore Fund for Cancer Research UK. MAST Group Ltd provided FIT kits.

Performance of two faecal immunochemical tests for the detection of advanced neoplasia at different positivity thresholds: a cross-sectional study of the Dutch national colorectal cancer screening programme

BACKGROUND

Faecal immunochemical tests (FITs) are recommended for colorectal cancer screening. Two frequently used FIT methods (FOB-Gold, Sentinel Diagnostics, Milan, Italy and OC-Sensor, Eiken Chemical, Tokyo, Japan) perform similarly in detecting advanced neoplasia (ie, colorectal cancer and advanced adenoma) at a fixed positivity cutoff for faecal haemoglobin concentration. It is unclear whether the performance of the two methods is also comparable at other thresholds. We compared the accuracy of the two assays in detecting advanced neoplasia across various thresholds.

METHODS

In a cross-sectional study in the Dutch national screening programme, individuals who were screening naive in 2016 (aged 55-75 years) living in the southwest region of the Netherlands were invited to use two different FIT assays on the same bowel movement. Eligible participants were randomly selected from municipal registers. Participants were referred for colonoscopy if either FIT assay result met the predefined positivity threshold (≥15 μg haemoglobin per g faeces). We compared the respective distributions of reported haemoglobin concentration and positivity rates with various FIT positivity thresholds. The performance of each FIT for identifying advanced neoplasia at colonoscopy in FIT-positive assays was compared with the area under the receiver operating characteristic curve.

FINDINGS

21 078 (50·0%) of 42 179 invitees completed both FIT assays. The distribution of haemoglobin concentrations differed significantly between the two FITs (p<0·0001), with higher positivity rates for OC-Sensor at FIT thresholds of 5 and 10 μg haemoglobin per g faeces, similar positivity rates at 15 and 20 μg haemoglobin per g faeces, and higher rates for FOB-Gold at FIT thresholds of 25-150 μg haemoglobin per g faeces. 2046 (9·7%) of 21 078 participants had at least one FIT assay that was positive and of these, 1724 (84·3%) attended colonoscopy. The accuracy of results in individuals undergoing colonoscopy did not significantly differ between the FITs, with an area under the receiver operating characteristic curve of 0·675 (95% CI 0·649 to 0·702) for FOB-Gold and 0·686 (0·661 to 0·712) for OC-Sensor (p=0·40). At identical positivity rates, the positive predictive value of the two FIT assays was similar (difference varying from 0·5% [95% CI -2·6 to 3·7] at a positivity rate of 3·5% to 2·4% [-2·5 to 7·3] at a positivity rate of 2·0%).

INTERPRETATION

The two widely used FITs have significantly different distributions of reported haemoglobin concentration and yield different positivity rates at equal thresholds. However, they perform similarly in detecting advanced neoplasia at a preset positivity rate. When implementing either FIT in a screening programme, the desired positivity rate that identifies participants to be referred for colonoscopy should first be set, guided by available resources and feasibility.

FUNDING

The Netherlands Organisation for Health Research and Development.

Long-term performance of colorectal cancerscreening programmes based on the faecal immunochemical test

BACKGROUND

The long-term performance of colorectal cancer (CRC) screening programmes based on a 2-year faecal immunochemical test (FIT) is still unclear.

METHODS

In a sample of 50 to 69-year-olds repeatedly screened with the FIT (OC-Hemodia latex agglutination test; cut-off: 20 µg haemoglobin/g faeces), we examined: (1) the FIT positivity rate, the CRC and advanced adenoma detection rate and the FIT's positive predictive value (PPV) for advanced neoplasia, at each round of screening and (2) the cumulative CRC and advanced adenoma detection rate after five rounds of FIT.

RESULTS

Over 12 years (2002-2014), 123 347 individuals were administered the FIT up to six times, and 781 CRCs and 4713 advanced adenomas were diagnosed. The CRC and advanced adenoma detection rates declined substantially from the first to the third (rate ratio (RR) 0.25, 95% CI 0.20 to 0.32) and second (RR 0.51, 95% CI 0.47 to 0.56) rounds, respectively, and then remained stable. The PPV for advanced neoplasia dropped by 18% in the second round (RR 0.82, 95% CI 0.77 to 0.89), with no further reduction thereafter due to a concomitant decline in the FIT positivity rate (RR first to sixth rounds: 0.56, 95% CI 0.53 to 0.60).The cumulative CRC and advanced adenoma detection rates over five consecutive rounds were 8.5‰ (95% CI 7.8 to 9.2), and 58.9‰ (95% CI 56.9 to 61.0), respectively.

CONCLUSIONS

Repeated FIT significantly reduces the burden of colorectal disease while facilitating an efficient use of colonoscopy resources. The cumulative detection rate after five rounds of FIT is similar to primary screening with colonoscopy, supporting the need to account for the cumulative sensitivity of repeated FITs when evaluating the test's efficacy.

Divergent Long-Term Detection Rates of Proximal and Distal Advanced Neoplasia in Fecal Immunochemical Test Screening Programs: A Retrospective Cohort Study

BACKGROUND

Short-term studies have reported that the fecal immunochemical test (FIT) is less accurate in detecting proximal than distal colorectal neoplasia.

OBJECTIVE

To assess the long-term detection rates for advanced adenoma and colorectal cancer (CRC), according to anatomical location.

DESIGN

Retrospective study.

SETTING

Population-based, organized screening program in the Veneto region of Italy.

PARTICIPANTS

Persons aged 50 to 69 years who completed 6 rounds of FIT screening.

MEASUREMENTS

At each screening round, the detection rates for advanced adenoma and cancer, as well as the proportional interval cancer rate (PICR), were calculated by anatomical location (proximal colon, distal colon, or rectum).

RESULTS

Between 2002 and 2014, a total of 123 347 participants had 441 647 FITs. The numbers of advanced adenomas and cancer cases detected, respectively, were 1704 and 200 in the proximal colon, 3703 and 324 in the distal colon, and 1220 and 209 in the rectum. Although the detection rate for proximal colon cancer declined only from the first to the second screening round (0.63 to 0.36 per 1000 screenees), the rate for both distal colon and rectal cancer steadily decreased across 6 rounds (distal colon, 1.65 in the first round to 0.17 in the sixth; rectum, 0.82 in the first round to 0.17 in the sixth). Similar trends were found for advanced adenoma (proximal colon, 5.32 in the first round to 4.22 in the sixth; distal colon, 15.2 in the first round to 5.02 in the sixth). Overall, 150 cases of interval cancer were diagnosed. The PICR was higher in the proximal colon (25.2% [95% CI, 19.9% to 31.5%]) than the distal colon (6.0% [CI, 3.9% to 8.9%]) or rectum (9.9% [CI, 6.9% to 13.7%]).

LIMITATIONS

Participants with irregular attendance were censored. Those who had a false-positive result on a previous FIT but negative colonoscopy results were included in subsequent rounds.

CONCLUSION

This FIT-based, multiple-round, long-term screening program had a negligible reduction in detection rates for neoplastic lesions in the proximal versus the distal colon after the first round. This was related to a higher PICR in the proximal colon and suboptimal efficacy in preventing the age-related proximal shifting of CRC.

PRIMARY FUNDING SOURCE

None.

Histopathologic study from a colorectal cancer screening in Chile: results from the first 2 years of an international collaboration between Chile and Japan

A national colorectal cancer (CRC) screening program began in Chile in 2012, which is an international collaboration between Japan and Chile and is based on a standardized protocol supported by Tokyo Medical and Dental University. We describe the results from the first 2 years of screening at one public hospital in Punta Arenas, Chile. Of 4124 asymptomatic individuals aged between 50 and 75 years, 485 participants with immunological fecal occult blood test values of at least 100 ng/ml and/or those with family histories of CRC underwent colonoscopies. Lesions were found in 291 participants, and 642 histologic samples were obtained. Chilean pathologists made the initial histologic diagnoses, and a Japanese pathologist reviewed the histologic slides and analyzed the results. Of the 291 participants with lesions, 60 (20.6%) were diagnosed with adenocarcinomas, of which 50 (83.3%) were early-phase adenocarcinomas (pTis or pT1), and 163 (56.0%) were diagnosed with conventional adenomas, of which 96 (58.9%) were high-risk adenomas. The cancer prevalence within the screened population was 1.5% (60 of 4124). The colonoscopy cancer detection rate was 12.4% (60 of 485). Notably, we detected one flat-depressed (0-IIc) lesion that measured 5 mm and had invaded the submucosa. The findings from this screening program are the first to show the histopathologic distributions of consecutive lesions and the high incidence of CRC in Chile. The high detection rates for high-risk adenomas and cancer support the feasibility of early CRC screening and its potential to reduce the mortality associated with CRC.

Improving diagnosis, prognosis and prediction by using biomarkers in CRC patients (Review)

Colorectal cancer (CRC) is among the most common cancers. In fact, it is placed in the third place among the most diagnosed cancer in men, after lung and prostate cancer, and in the second one for the most diagnosed cancer in women, following breast cancer. Moreover, its high mortality rates classifies it among the leading causes of cancer‑related death worldwide. Thus, in order to help clinicians to optimize their practice, it is crucial to introduce more effective tools that will improve not only early diagnosis, but also prediction of the most likely progression of the disease and response to chemotherapy. In that way, they will be able to decrease both morbidity and mortality of their patients. In accordance with that, colon cancer research has described numerous biomarkers for diagnostic, prognostic and predictive purposes that either alone or as part of a panel would help improve patient's clinical management. This review aims to describe the most accepted biomarkers among those proposed for use in CRC divided based on the clinical specimen that is examined (tissue, faeces or blood) along with their restrictions. Lastly, new insight in CRC monitoring will be discussed presenting promising emerging biomarkers (telomerase activity, telomere length and micronuclei frequency).

A large proportion of fecal immunochemical test-positive participants in colorectal cancer screening is symptomatic

Background

Symptomatic invitees are advised not to participate in colorectal cancer (CRC) screening but to directly consult their general practitioner (GP), because fecal immunochemical test (FIT) sensitivity for cancer is not optimal. This recommendation may not always be followed in daily practice. We evaluated how many FIT-positive participants had CRC-related symptoms and whether the presence of symptoms was associated with the presence and location of CRC/advanced neoplasia.

Methods

We prospectively collected data on CRC-related symptoms in all FIT-positive participants in the Dutch CRC screening program, referred to our endoscopy centers between 2014 and 2016, and evaluated whether symptoms were associated with detected CRC/advanced neoplasia at colonoscopy.

Results

Of 527 FIT-positive participants, 314 had advanced neoplasia, of which 41 had CRC. Overall, 246 (47%; 95% confidence interval (CI) 0.42–0.51) reported CRC-related symptoms. A change in bowel habits (odds ratio (OR) 2.86, CI 1.23–6.62) and visible blood in stool (OR 8.65, CI 2.34–32.0) were associated with the detection of CRC at colonoscopy. We did not observe significant associations between evaluated symptoms and advanced neoplasia.

Conclusions

A large proportion of FIT-positive screening participants have CRC-related symptoms. This suggests that current instructions do not retain symptomatic screening invitees from participation and awareness of CRC-related symptoms is inadequate.

Long-term risk of colorectal cancer after negative colonoscopy in a Danish gFOBT screening cohort

Faecal occult blood test (FOBT) screening for colorectal cancer (CRC) is implemented in several countries. Approximately half of all screen positive persons have negative colonoscopy, but consensus is lacking on how these persons should be followed up. Health authorities in Denmark and The Netherlands recommend suspending screening for 8-10 years, while patients in UK are invited to screening after 2 years. In this cohort-study, we followed 166,277 individuals invited to FOBT-screening in 2005-2006 and a reference group comprising the remaining 1,240,348 Danes of the same age. We linked Danish population and health service registers to obtain information about colonoscopy outcome and incident CRC. We estimated CRC risk by colonoscopy outcome (adenoma, other colorectal pathology or negative colonoscopy) for the reference group, the screening group, and subgroups. Persons with positive screening FOBT followed by negative colonoscopy had the same long-term CRC risk as persons with adenoma detected due to a positive screening FOBT (aHR 1.33, 95% CI: 0.65-2.71). We found no difference in the long-term CRC risk between persons with negative colonoscopy after a positive FOBT screening test and the unscreened reference population (aHR 1.05, 95% CI: 0.62-1.78). Since FOBT screen positive persons in our study remained at average risk of CRC despite of a negative index colonoscopy, we question the safety of suspending FOBT screening for this group. It needs to be monitored whether recent efforts to improve colonoscopy quality have been successful in ensuring low CRC risk after negative colonoscopy also in FOBT positive persons.

Fecal immunochemical test for colorectal cancer from a prospective cohort with 513,283 individuals: Providing detailed number needed to scope (NNS) before colonoscopy

The fecal immunochemical test (FIT) is underutilized, in part, because its benefits have not been fully understood. We assessed the relationship of FIT values with cancer incidence and mortality, and explored how repeated administrations of FIT could aid clinicians. A cohort with 513,283 adults in Taiwan participated in a screening program between 1994 and the end of 2007. Colorectal cancer was identified from National Cancer Registry and not from colonoscopy. Positive FIT was FIT ≥ 100 ng/mL. Number needed to scope (NNS) to identify 1 cancer by different FIT values was calculated for the study time. Only 4% of subjects had FIT ≥ 100 ng/mL but contributed 40% of cancer cases, leading to a NNS of 25 for finding 1 in this group. However, within the same FIT ≥ 100 ng/mL, NNS was different by age: 10 for age 60 to 69 years, 42 for age 40 to 49 years, and 156 for age 20 to 39 years. Furthermore, within the same age, NNS was different by FIT values, for instance, 66 for FIT 100 to 199 ng/mL and 12 for FIT 600 to 799 ng/mL, a difference of 5-fold for age 50 to 59 years. The dose-response relationship of FIT can facilitate consultation regarding the need for colonoscopy by providing a quantitative NNS for cancer risk, an index easily understood by patients. Our conclusion made use of (a) age-dependent and (b) quantitative interpretation of FIT values. This single cutpoint practice obliterates a large amount of valuable cancer risk information available to patients.

Fecal hemoglobin concentration is useful for risk stratification of advanced colorectal neoplasia

BACKGROUND

Although a fecal immunochemical test (FIT) allows quantitation of fecal hemoglobin (f-Hb), it is typically used as a binary result to identify subjects above a predetermined cut-off concentration.

AIMS

To investigate whether f-Hb concentration is useful for risk stratification of advanced colorectal neoplasia (CRN).

METHODS

This was a retrospective study conducted in a university hospital in Korea. Of 34,547 participants who underwent FIT from June 2013 to May 2015, 1532 (4.4%) showed positive results (≥100ng Hb/ml). Of participants with positive results, 738 subjects aged ≥50 years who underwent colonoscopy were analyzed.

RESULTS

Increasing quartile of f-Hb concentration (Q4 vs. Q1; odds ratio, 3.87; 95% confidence interval, 2.36-6.34), as well as older age, male sex, smoking, and metabolic syndrome (MetS), was significantly associated with a higher prevalence of advanced CRN. Risk for advanced CRN increased 5.13-, 4.27-, 5.12-, and 7.15-fold, respectively, among individuals with f-Hb in the fourth quartile who had risk factors such as age ≥70 years, male sex, smoking, and MetS compared with individuals with first quartile levels of f-Hb who did not have those risk factors.

CONCLUSION

In addition to age, sex, smoking status, and MetS, f-Hb concentration in individuals with positive results from FIT can be used to stratify the probability of detection of advanced CRN.

Screening for Colorectal Cancer: A Systematic Review and Meta-Analysis

To evaluate the effectiveness of colorectal cancer (CRC) screening in asymptomatic adults. A search was conducted of the Medline, Embase, and the Cochrane Library databases. A targeted search of PubMed was conducted for on-topic randomized controlled trials (RCTs). Meta-analysis across 4 RCTs for guaiac fecal occult blood testing (gFOBT) and flexible sigmoidoscopy (FS) screening showed a reduction of 18% (risk ratio [RR], 0.82; 95% CI [CI], 0.73-0.92) and 26% (RR, 0.74; 95% CI, 0.67-0.83) in CRC mortality for the screening group compared to controls, respectively. The number needed to screen (NNS) were 377 (95% CI, 249-887) and 864 (95% CI, 672-1266) for gFOBT and FS screening, respectively. A reduction of 8% and 27% in incidence of late-stage CRC was also observed for gFOBT and FS screening, respectively, but both had no significant effect on all-cause mortality. A single RCT found that screening with immunochemical fecal occult blood test (iFOBT) had no significant impact on CRC mortality (RR, 0.88; 95% CI, 0.72-1.07). Screening with FS has potential harms such as perforation, major and minor bleeding, and death from the procedure or from follow-up colonoscopy. gFOBT and FS screening reduce CRC mortality and incidence of late-stage disease. The absolute effect and NNS were much more favorable for older adults (≥ 60 years), suggesting that a targeted screening approach may avoid exposing younger adults to the harms of CRC screening, from which they are unlikely to derive any significant benefit. Although there is insufficient RCT evidence on the impact of iFOBT on mortality outcomes. compared to gFOBT, this test showed higher sensitivity and comparable specificity, indicating the need to update and reevaluate the evidence in light of future high-quality research. The protocol for this systematic review have been published with PROSPERO 2014: CRD42014009777.

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

Objectives

To 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 methods

We 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.

Results

Of 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).

Conclusion

In areas where other advance screening methods of CRC are not feasible, the use of FIT can be considered.

Impact of Screening Program on Incidence of Colorectal Cancer: A Cohort Study in Italy

OBJECTIVES

Colorectal cancer (CRC) screening using the fecal occult blood test (FOBT) has been shown to be effective in reducing cause-specific mortality. However, although it detects pre-cancerous adenomas, it is uncertain whether FOBT reduces the incidence of invasive cancer. The objective is to evaluate the impact of screening with immunochemical FOBT (FIT) on CRC incidence and mortality.

METHODS

An organized screening program was implemented in 2005 in the province of Reggio Emilia (Northern Italy). The program invites the resident population aged 50-69 for FIT every 2 years. Subjects who test positive are referred for colonoscopy. Incidence was studied through cancer registry. Person-times of people aged 50-74 from 1997 to 2012 were classified for exposure to screening according to age and period. Furthermore, two open cohorts-one never screened (aged 50-69 in 1997) and one invited for screening (aged 50-69 in 2005)-were followed up for 8 years.

RESULTS

A total of 171,785 people have been invited, and approximately 70% have undergone FIT at least once (272,197 tests). The rate of colonoscopy participation has been about 90%, and 2896 cancers have been recorded (1237 in the screening period). The age-adjusted and sex-adjusted incidence rate ratios as compared with pre-screening were 1.60 (95% confidence interval (CI), 1.43-1.79), 0.86 (95% CI, 0.78-0.94), and 0.59 (95% CI, 0.50-0.69) for the first round, subsequent rounds, and post screening, respectively. Cumulative incidence and incidence-based mortality decreased by 10% (95% CI, 3-17%) and 27% (95% CI, 15-37%), respectively.

CONCLUSIONS

FIT screening leads to a decrease in the incidence of CRC and in its mortality.

Improving uptake of screening for colorectal cancer: a study on invitation strategies and different test kit use

OBJECTIVE

The aim of this study was to compare the uptake of mail-delivered tests for colorectal cancer screening. We assessed the effect of an advance notification letter and a reminder letter, and analysed the proportion of inappropriately handled tests.

MATERIALS AND METHODS

Fifteen thousand randomly selected residents of Latvia aged 50-74 years were allocated to receive one of three different test systems: either a guaiac faecal occult blood test (gFOBT) or one of two laboratory-based immunochemical tests (FIT) - FOB Gold or OC-Sensor. Half of the target population received an advance notification letter; all nonresponders were sent a reminder letter.

RESULTS

The uptake of screening was 31.2% for the gFOBT, 44.7% for FOB Gold and 47.4% for the OC-Sensor (odds ratio 0.55; 95% confidence interval 0.51-0.60 for gFOBT vs. FOB Gold; odds ratio 0.90; 95% confidence interval 0.83-0.98 for FOB Gold vs. OC-Sensor). The uptake in the gFOBT group was improved by the advance notification letter (7.7%, P<0.0001). 30.9% returned tests were received after the reminder letter. The proportion of tests that could not be analysed because of inadequate handling was 0.9% for gFOBT, 4.4% for FOB Gold and 0.2% for the OC-Sensor (P=0.002 for gFOBT vs. OC-Sensor; P<0.001 for all comparisons vs. FOB Gold).

CONCLUSION

The use of FIT resulted in higher uptake. Receipt of a reminder letter was critical to participation, but the use of an advance notification letter was important mainly for gFOBT. The proportion of inappropriately handled tests was markedly higher for FOB Gold.

Impact on colorectal cancer mortality of screening programmes based on the faecal immunochemical test

OBJECTIVE

Colorectal cancer (CRC) screening programmes based on the guaiac faecal occult blood test (gFOBT) reduce CRC-specific mortality. Several studies have shown higher sensitivity with the faecal immunochemical test (FIT) compared with gFOBT. We carried out an ecological study to evaluate the impact of FIT-based screening programmes on CRC mortality.

DESIGN

In the Veneto Region (Italy), biennial FIT-based screening programmes that invited 50-69-year-old residents were introduced in different areas between 2002 and 2009. We compared CRC mortality rates from 1995 to 2011 between the areas where screening started in 2002-2004 (early screening areas (ESA)) and areas that introduced the screening in 2008-2009 (late screening areas (LSA)) using Poisson regression models. We also compared available data on CRC incidence rates (1995-2007) and surgical resection rates (2001-2012).

RESULTS

Before the introduction of screening, CRC mortality and incidence rates in the two areas were similar. Compared with 1995-2000, 2006-2011 mortality rates were 22% lower in the ESA than in the LSA (rate ratio (RR)=0.78; 95% CI 0.68 to 0.89). The reduction was larger in women (RR=0.64; CI 0.51 to 0.80) than in men (RR=0.87; CI 0.73 to 1.04). In the ESA, incidence and surgery rates peaked during the introduction of the screening programme and then returned to the baseline (2006-2007 incidence) or dropped below initial values (surgery after 2007).

CONCLUSIONS

FIT-based screening programmes were associated with a significant reduction in CRC mortality. This effect took place much earlier than reported by gFOBT-based trials and observational studies.

Programmatic screening for colorectal cancer: the COLONPREV study

The COLONPREV study is an ongoing multicenter, nationwide, randomized controlled trial aimed at evaluating the efficacy of once-only colonoscopy and biennial fecal immunochemical testing with respect to the reduction of CRC-related mortality at 10 years in average-risk colorectal cancer screening population. Following a pragmatic approach, this study may contribute to establishing the most cost-effective strategy in a programmatic, population-based setting. In this review, we report the results obtained at the first screening round, as well as others achieved in nested evaluations using the COLONPREV dataset with the aim of clarifying some controversial issues on the different strategies of colorectal cancer screening.

Sustained participation, colonoscopy uptake and adenoma detection rates over two rounds of the Tallaght-Trinity College colorectal cancer screening programme with the faecal immunological test

BACKGROUND

Studies to date support the use of the faecal immunological test (FIT) in colorectal cancer screening programmes, and it has been widely adopted across Europe, Canada, Australia, and the USA. Successive screening rounds are necessary to detect and prevent colorectal cancer. The overall success of FIT screening will depend on several factors, the most important probably being the acceptability of repeated screening rounds. Being a newer form of occult blood testing, there is little data available on its overall efficacy over time.

AIMS

The aim of this study was to assess key performance indices during a second round of FIT screening in an Irish cohort and to compare results between successive rounds.

METHODS

A biennial, two tests, two-step design with postal invites and colonoscopy offered to anyone with a single FIT greater than 100 ngHb/ml was used. Recommended key performance measures were assessed and compared, including participation, positivity, colonoscopy uptake and adenoma and cancer detection rates.

RESULTS

In round two, 9863 individuals (98.6%) of the round one cohort were contacted. The round two participation rate was 47.5% (n=4685), only slightly lower than the 51% registered in round one. Male sex and younger age were associated with lower uptake. Overall positivity decreased from 10 to 8% over time (P<0.0001). Although the number of cancers detected during round two decreased significantly, overall neoplasia detection rates remained stable; positive predictive values for cancer and adenoma were 4 versus 1% and 37 versus 35%, respectively.

CONCLUSION

Repeated rounds of FIT screening in the Tallaght-Trinity College cohort achieved stable participation and neoplasia detection rates, suggesting that this mode of screening is both effective and acceptable to patients in the long term.

Increasing colorectal cancer screening in an overdue population: participation and cost impacts of adding telephone calls to a FIT mailing program

Many people who live in rural areas face distance barriers to colonoscopy. Our previous study demonstrated the utility of mailing fecal immunochemical tests (FIT) to average risk patients overdue for colorectal cancer (CRC screening). The aims of this study were to determine if introductory and reminder telephone calls would increase the proportion of returned FITs as well as to compare costs. Average risk patients overdue for CRC screening received a high intensity intervention (HII), which included an introductory telephone call to see if they were interested in taking a FIT prior to mailing the test out and reminder phone calls if the FIT was not returned. This HII group was compared to our previous low intensity intervention (LII) where a FIT was mailed to a similar group of veterans with no telephone contact. While a higher proportion of eligible respondents returned FITs in the LII (92 vs. 45 %), there was a much higher proportion of FITs returned out of those mailed in the HII (85 vs. 14 %). The fewer wasted FITs in the HII led to it having lower cost per FIT returned ($27.43 vs. $44.86). Given that either intervention is a feasible approach for patients overdue for CRC screening, health care providers should consider offering FITs using a home-based mailing program along with other evidence-based CRC screening options to average risk patients. Factors such as location, patient population, FIT cost and reimbursement, and personnel costs need to be considered when deciding the most effective way to implement FIT screening.

Colorectal cancer screening: tests, strategies, and perspectives

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

Test characteristics of faecal immunochemical tests (FIT) compared with optical colonoscopy

BACKGROUND

Faecal occult blood tests are often the initial test in population-based screening. We aimed to: 1) compare the results of single sample faecal immunochemical tests (FITs) with colonoscopy, and 2) calculate the sensitivity for proximal vs. distal adenomatous polyps or cancer.

METHODS

Individuals scheduled for a colonoscopy were invited to complete a FIT prior to their colonoscopy preparation. FIT results were classified as positive, negative, or invalid. Colonoscopy reports were reviewed and abstracted. Because of product issues, four different FIT manufacturers were used. The test characteristics for each FIT manufacturer were calculated for advanced adenomatous polyps or cancer according to broad reason for colonoscopy (screening or surveillance/diagnostic).

RESULTS

Of those invited, 1,026 individuals (43.9%) completed their colonoscopy and had a valid FIT result. The overall sensitivity of the FITs (95% confidence intervals) was 0.18 (0.10 to 0.28) and specificity was 0.90 (0.87 to 0.91) for advanced adenomas or cancer. The sensitivity for distal lesions was 0.23 (0.11 to 0.38) and for proximal lesions was 0.09 (0.02 to 0.25). The odds ratio of an individual with a distal advanced adenoma or cancer testing positive was 2.68 (1.20 to 5.99). The two individuals with colorectal cancer tested negative, as did one individual with high-grade dysplasia.

CONCLUSIONS

The sensitivity of a single-sample FIT for advanced adenomas or cancer was low. Individuals with distal adenomas had a higher odds of testing positive than those with proximal lesions or no lesions.

Validity of fecal occult blood test in the national cancer screening program, Korea

AIM

The aims of the current study were to assess the validity of the fecal occult blood test (FOBT) in an organized screening setting in Korea and to determine factors associated with FOBT validity, such as screening round, age group, and anatomical location of the cancer.

METHODS

Study participants were those who were 50 years and older who received an FOBT through the National Cancer Screening Program between 2004 and 2007. Colorectal cancer diagnoses were ascertained through linkage with the Korean National Cancer Incidence Database. The positivity rate, colorectal cancer detection rate, interval cancer rate, sensitivity, specificity, and positive predictive value of the FOBT were calculated.

RESULTS

A total of 2,193,093 tests were included in the analysis. Overall, the sensitivity of the FOBT for colorectal cancer was 59.7% for the first round and 56.1% for the subsequent round. Sensitivity was highest for distal colon cancer (65.9%) in the first round, and for rectal cancer (58.4%) for the subsequent round. The sensitivity and positive predictive value of the FOBT generally improved between 2004 and 2008.

CONCLUSIONS

The FOBT showed reasonable validity in an organized screening setting, and the validity of the FOBT varied by screening round, anatomical location, and screening year.

Screening and Primary prevention of Colorectal Cancer: a Review of sex-specific and site-specific differences

Background

Colorectal cancer (CRC) is the second commonest cancer in England. Incidence rates for colorectal adenomas and advanced colorectal neoplasia are higher in men than in women of all age groups. The male-to-female ratio for CRC incidence rates differs for different parts of the large bowel.

Objective

To summarize the current evidence on colorectal screening and prevention, focussing on potential differences in benefits between sexes and colorectal sites.

Methods

(i), We reviewed the evidence from randomized controlled trials (RCTs) of the impact of different screening approaches on CRC incidence and mortality, overall, for each sex separately, and for subsites of the large bowel. (ii) We reviewed studies comparing detection parameters for faecal immunochemical tests for haemoglobin (FIT) with guaiac FOBt (gFOBt). (iii) The role of aspirin in CRC prevention in the general population was reviewed using evidence from RCTs, with specific emphasis on the differences observed between sexes and lesion site.

Results

(i) Our intention-to-treat random-effects meta-analysis showed that once-only flexible sigmoidoscopy (FS) screening performed on average-risk individuals aged 55 + decreased CRC incidence by 18% and mortality by 28%, but sex-specific results were lacking. (ii) Modern quantitative FIT were superior to qualitative gFOBt in average-risk population screening in their ability to discriminate between individuals with and without colorectal neoplasia. Some recent FIT studies suggest varying operating characteristics in men and women. (iii) Evidence of an effect of aspirin on the incidence of CRC (in particular, proximal disease) in both sexes aged 40 and over at average-risk of CRC is emerging.

Conclusions

We encourage researchers of CRC screening and prevention to publish their results by sex where possible. Pilot studies should be undertaken before implementation of quantitative FIT in a national screening programme to establish the appropriate threshold. Finally, individual risk assessment for CRC and non-CRC events, will be necessary to make an informed decision on whether a patient should receive aspirin chemoprevention.

Uptake and positive predictive value of fecal occult blood tests: A randomized controlled trial

OBJECTIVE

The aim of this study is to compare the uptake of three mailed high-sensitivity fecal occult blood tests (FOBTs).

METHODS

We conducted a parallel 3-arm randomized controlled trial in an integrated healthcare delivery system in Washington State. From January 2010 through February 2011, automated data were used to identify potentially eligible patients aged 50-74 due for colorectal cancer screening. Participants were mailed one of three FOBT kits (1-sample OC-Auto® fecal immunochemical test [FIT], 2-sample InSure® FIT, or 3-sample guaiac Hemoccult SENSA®), instructions, and a postage-paid return envelope. We performed a modified intent-to-treat analysis with return of any FOBT within 6 months of randomization as the primary outcome.

RESULTS

Of the 9922 people invited, 2873 returned surveys, 2263 were randomized, and 2234 were analyzed. FOBTs were returned by 1431 participants. At 6 months post-randomization, the proportions screened by any FOBT were 0.69 (95% confidence interval [CI] 0.66-0.72) for the OC-Auto arm, 0.64 (95% CI: 0.61-0.68) for the InSure arm, and 0.61 (95% CI: 0.58-0.65) for the Hemoccult SENSA arm (P<0.001 for any difference). Pairwise comparisons showed significant differences between the OC-Auto group and each of the other groups after correction for multiple comparisons.

CONCLUSION

Uptake of mailed FOBT kits varies by kit type.

Comparative evaluation of nine faecal immunochemical tests for the detection of colorectal cancer

BACKGROUND

Faecal immunochemical tests (FITs) for haemoglobin are increasingly used for non-invasive screening for colorectal cancer (CRC) but large scale comparative studies of different FITs for detection of CRC, overall and by stage, are sparse. We aimed to determine and compare performance of different FITs for the detection of CRC, and to assess their stage-specific sensitivities.

MATERIAL AND METHODS

We assessed sensitivity, specificity and their corresponding 95% confidence intervals for six qualitative FITs among 74 CRC cases (59% stage I or II cancers) and 1480 controls free of colorectal neoplasm. Overall and stage-specific receiver operating characteristic curves were derived for three quantitative FITs. The areas under the curves (AUCs) were calculated and compared.

RESULTS

Pairs of overall sensitivity and specificity of the qualitative FITs ranged from 66% and 96% to 92% and 62%, respectively. For the three quantitative tests, AUCs ranged from 0.90 to 0.92, with sensitivities ranging from 80% to 87% at cut-offs yielding 90% specificity. AUCs ranged from 0.85 to 0.92, 0.94 to 0.96, and 0.86 to 0.93 for stage I, stage II and advanced stages (stage III and IV) cancers, respectively. At a specificity of 90%, the tests detected 65%-85% of stage I cancers.

CONCLUSION

The diagnostic performance of FITs regarding detection of CRC is promising, even though the pre-defined cut-offs of some of the qualitative FITs need to be adjusted to limit false-positive rates in screening setting. At cut-off levels yielding 90% specificity, the quantitative tests detected the vast majority of CRCs, even at early stages.

Evaluation of a home-based colorectal cancer screening intervention in a rural state

PURPOSE

Distance from health care facilities can be a barrier to colorectal cancer (CRC) screening, especially for colonoscopy. Alternatively, an improved at-home stool-based screening tool, the fecal immunochemical test (FIT), requires only a single sample and has a better sensitivity-specificity balance compared to traditional guaiac fecal occult blood tests. Our objective was to determine if FITs mailed to asymptomatic, average-risk patients overdue for screening resulted in higher screening rates versus mailing educational materials alone or no intervention (ie, usual care).

METHODS

Veterans ages 51-64, asymptomatic, at average risk for CRC, overdue for screening and in a veterans administration (VA) catchment area covering a large rural population were randomly assigned to 3 groups: (1) education only (Ed) group: mailed CRC educational materials and a survey of screening history and preferences (N = 499); (2) FIT group: mailed the FIT, plus educational materials and survey (N = 500); and (3) usual care (UC) group: received no mailings (N = 500).

FINDINGS

At 6 months postintervention, 21% of the FIT group had received CRC screening by any method compared to 6% of the Ed group (and 6% of the UC group) (P < .0001). Of the 105 respondents from the FIT group, 71 (68%) were eligible to take the FIT. Of those, 64 (90%) completed the FIT and 8 (12%) tested positive.

CONCLUSIONS

This low-intensity intervention of mailing FITs to average risk patients overdue for screening resulted in a significantly higher screening rate than educational materials alone or usual care, and may be of particular interest in rural areas.

Diagnostic inconsistency of faecal immunochemical tests for haemoglobin in population screening of colorectal cancer

BACKGROUND

There is currently very little data available on the consistency of quantitative and qualitative faecal immunochemical test (FIT) for colorectal cancer screening.

METHODS

A representative random population (n=1889, 40-74 year olds) in Jiashan, China was invited for FIT screening in 2012. Faecal samples were collected by a single specimen collection device and simultaneously tested by a quantitative FIT (OC-SENSOR, OC) and two qualitative FITs (FIT A and FIT B with intrinsic positive haemoglobin cut-off concentrations of 20 μg Hb/g faeces and 40 μg Hb/g faeces, respectively). The observational criteria for a positive result of the qualitative FIT were set according to the density of the colour appearing in the test strip. The results produced by the quantitative and qualitative FIT for each sample were compared. κ coefficient was used to measure consistency.

RESULTS

A total of 1368 (72.4%) individuals returned faecal samples. Both FIT A and FIT B precisely identified all faecal samples with haemoglobin concentration above 100 μg Hb/g faeces, but the overall consistency was poor for OC & FIT A (κ=0.32, 95% CI 0.20-0.44) and was moderate for OC & FIT B (κ=0.74, 95% CI 0.64-0.85). A more favourable consistency (κ=0.64, 95% CI 0.57-0.72) was achieved when a different positive criterion was employed for FIT A.

CONCLUSIONS

The diagnostic inconsistency between quantitative and qualitative FITs mainly exists in the faecal samples with low haemoglobin concentrations. Refining the criterion for a positive result may be a feasible way to improve the accuracy of qualitative FIT.

Fecal miR-106a is a useful marker for colorectal cancer patients with false-negative results in immunochemical fecal occult blood test

BACKGROUND

Immunochemical fecal occult blood test (iFOBT) is widely used for colorectal cancer screening; however, its sensitivity is insufficient. We recently reported a fecal microRNA (miRNA) test (FmiRT) to detect colorectal cancer. In this study, we investigated a new colorectal cancer screening method combining iFOBT and FmiRT to improve the sensitivity compared with iFOBT alone.

METHODS

In total, 117 colorectal cancer patients and 107 healthy volunteers were enrolled. Ten-milligram fecal samples were collected and iFOBT was conducted. Fecal RNA was extracted from residuum of iFOBT and then the expression of 14 kinds of miRNA was analyzed for the FmiRT using real-time reverse transcription PCR.

RESULTS

Levels of fecal miR-106a expression in iFOBT+ patients and iFOBT- patients were significantly higher than in healthy volunteers (P = 0.001). The sensitivity and specificity of FmiRT using miR-106a were 34.2% and 97.2%, and those of iFOBT were 60.7% and 98.1%, respectively. The overall sensitivity and specificity of the new screening method combining iFOBT and FmiRT were 70.9% and 96.3%, respectively. One quarter of colorectal cancer patients with false-negative iFOBT seemed to be true positive upon adding FmiRT using fecal miR-106a.

CONCLUSIONS

Fecal miR-106a is a good molecular marker to identify colorectal cancer patients from among those with negative iFOBT results. FmiRT combined with iFOBT may improve the sensitivity to detect colorectal cancer.

IMPACT

We have shown the usefulness of fecal miR-106a to detect the colorectal cancer patients among those with negative iFOBT results.

The "Iowa get screened" colon cancer screening program

OBJECTIVE

To implement a colon cancer screening program for uninsured or underinsured Iowans.

METHODS

All 1995 uninsured patients or patients with Iowa Care insurance aged 50 to 64 years attending the University of Iowa Clinic or the Iowa City Free Medical Clinic were mailed information about the project. Recruitment also took place in person, by having the clinic receptionist hand subjects a research packet, and through community posters. Individuals with colonic symptoms or who were up to date with screening were ineligible. Eligible subjects received a free fecal immunochemical test (FIT), and those with positive FITs were provided with a colonoscopy at no cost to them.

RESULTS

Of 449 individuals who completed eligibility forms (23% of the study population), 297 (66%) were eligible and were provided with an FIT. Two-hundred thirty-five (79%) returned a stool sample, with 49 (21%) testing positive. Thirty of the 49 (61%) individuals had a colonoscopy, and 20 individuals had at least 1 polyp biopsied. Thirteen individuals had at least 1 tubular adenoma; 2 had adenomas more than 1 cm in diameter, with no colon cancers identified. Face-to-face recruitment had the highest rate of returned FITs (72%) compared with handing the subject a research packet (3%) or a mailing only (9%) (Chi-square, P < .001).

CONCLUSION

There was high interest in and compliance with colon cancer screening using a FIT among underinsured individuals. Although the FIT positivity rate was higher than expected, many individuals did not complete recommended follow-up colonoscopies. Population-based strategies for offering FIT could significantly increase colon cancer screening among disadvantaged individuals, but programs will have to develop sustainable mechanisms to include the necessary organization and address substantial costs of providing mass screening, as well as facilitating and providing colonoscopies for those who test positive.

Current status of screening for colorectal cancer

BACKGROUND

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Diagnostic yield of a one sample immunochemical test at different cut-off values in an organised screening programme for colorectal cancer

BACKGROUND

Quantitative immunochemical faecal occult blood tests have become the recommended tests for colorectal cancer screening. The aim of this study was to complete our knowledge on the performance of one of the quantitative immunochemical tests available, FOB-Gold, and to propose a possible strategy for an organised screening programme.

PATIENTS AND METHODS

Within the French organised screening programme, 23,231 average-risk individuals, aged 50-74 performed both a 3-day Hemoccult test and a 1-day FOB-Gold test. Performances of the immunochemical test were evaluated at different cut-off levels.

RESULTS

The positivity rate for the Hemoccult was 2.1% and for the FOB-Gold varied between 4.6% (cut-off value of 100 ng/mL, the lowest studied cut-off) and 2.1% (cut-off value of 352 ng/mL). The number of colonoscopies decreased with increasing cut-off values by 21.5% (150 ng/mL), 35.4% (200 ng/mL) and 53.3% (352 ng/mL). The corresponding miss rate for CRC was respectively 6.4%, 11.1% and 22.2%, and for advanced adenoma respectively 16.3%, 29.2% and 43.6%. Compared with the reference cut-off for the FOB-Gold (100 ng/mL) the miss rate for Hemoccult was 53% for CRC and 77% for advanced adenoma.

CONCLUSION

The study suggests that in countries with colonoscopy facilities compatible with a screening test positivity rate of up to 5%, use of a 1-day test with a cut-off value between 100 and 150 ng/mL could be the recommended strategy. Further increasing the cut-off value up to the same positivity rate as Hemoccult could be used in areas with limited access to colonoscopy.

Screening for colorectal cancer with immunochemical faecal occult blood tests

Population-based studies have shown that guaiac faecal occult blood testing followed by colonoscopy in case of positivity can reduce colorectal cancer mortality. However these tests have been criticised for their fairly low sensitivity. For this reason attention has been given to alternative tests. The aim of this paper is to review the evidence for screening for colorectal cancer using qualitative immunochemical faecal occult blood tests. For the complete range of tested cut-off values, immunochemical faecal occult blood tests lead to higher diagnostic yield, improved sensitivity and greater participation. The optimal number of samples and the optimal cut-off value has to suit local resources and the acceptability of missed cancers. All economic evaluations, despite some differences between studies, add further arguments to support the opinion that the immunochemical faecal occult blood test is currently the most cost-effective screening test for average-risk populations. These economic evaluations provide strong arguments in favour of the 1-sample strategy. With decreasing the cut-off value similar performances can be achieved with one-compared to two day sampling. Too few data are currently available to accurately compare existing qualitative tests.

Similar fecal immunochemical test results in screening and referral colorectal cancer

AIM: To improve the interpretation of fecal immunochemical test (FIT) results in colorectal cancer (CRC) cases from screening and referral cohorts.

METHODS: In this comparative observational study, two prospective cohorts of CRC cases were compared. The first cohort was obtained from 10 322 average risk subjects invited for CRC screening with FIT, of which, only subjects with a positive FIT were referred for colonoscopy. The second cohort was obtained from 3637 subjects scheduled for elective colonoscopy with a positive FIT result. The same FIT and positivity threshold (OC sensor; ≥ 50 ng/mL) was used in both cohorts. Colonoscopy was performed in all referral subjects and in FIT positive screening subjects. All CRC cases were selected from both cohorts. Outcome measurements were mean FIT results and FIT scores per tissue tumor stage (T stage).

RESULTS: One hundred and eighteen patients with CRC were included in the present study: 28 cases obtained from the screening cohort (64% male; mean age 65 years, SD 6.5) and 90 cases obtained from the referral cohort (58% male; mean age 69 years, SD 9.8). The mean FIT results found were higher in the referral cohort (829 ± 302 ng/mL vs 613 ± 368 ng/mL, P = 0.02). Tissue tumor stage (T stage) distribution was different between both populations [screening population: 13 (46%) T1, eight (29%) T2, six (21%) T3, one (4%) T4 carcinoma; referral population: 12 (13%) T1, 22 (24%) T2, 52 (58%) T3, four (4%) T4 carcinoma], and higher T stage was significantly associated with higher FIT results (P < 0.001). Per tumor stage, no significant difference in mean FIT results was observed (screening vs referral: T1 498 ± 382 ng/mL vs 725 ± 374 ng/mL, P = 0.22; T2 787 ± 303 ng/mL vs 794 ± 341 ng/mL, P = 0.79; T3 563 ± 368 ng/mL vs 870 ± 258 ng/mL, P = 0.13; T4 not available). After correction for T stage in logistic regression analysis, no significant differences in mean FIT results were observed between both types of cohorts (P = 0.10).

CONCLUSION: Differences in T stage distribution largely explain differences in FIT results between screening and referral cohorts. Therefore, FIT results should be reported according to T stage.

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

BACKGROUND

Immunochemical 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.

METHODS

A 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.

RESULTS

Positivity 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.

CONCLUSION

For 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 200 ng/mL (OC-Sensor) and 176 and 234 ng/mL (FOB-Gold). Data on the ease of test interpretation and cost-effectiveness now necessary to make definitive choices.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.