Measuring interval cancers in population-based screening using different assays of fecal occult blood testing: The district of Florence experience

Results of Compliant Participation in Five Rounds of Fecal Immunochemical Test Screening for Colorectal Cancer

BACKGROUND & AIMS

We investigated the magnitude and temporal patterns of the decreasing trend in main performance measures of fecal immunochemical test (FIT) screening for colorectal cancer (CRC) observed in second and subsequent rounds.

METHODS

We followed up 494,187 participants from the first round of a regional biennial FIT screening program in Italy (cut-off value for positivity, 20 μg hemoglobin/g feces) for 5 total rounds (2005-2016). At each round, only compliant participants were eligible. Performance measures from the first, third, fourth, and fifth rounds were compared with those from the second round (the first incidence round) using rate ratios from multivariate Poisson regression models and relative risk ratios from multinomial logistic regression models.

RESULTS

Between the second and the third rounds, a significant 20% to 30% decrease was found in the proportion of men with a positive FIT result (from 5.2% to 4.3%) and in detection rates of advanced adenoma (from 13.4 to 10.2 per 1000), CRC (from 1.7 to 1.4 per 1000), and advanced neoplasia (from 15.1 to 11.6 per 1000). Positive predictive values (PPVs) decreased by 10% or less between the second and third rounds. Detection rates and PPVs for adenoma stabilized by the fourth and fifth rounds. The PPVs for advanced adenoma, CRC, and advanced neoplasia decreased slightly in men and women by the fourth and fifth rounds. The detection rate of proximal colon cancer stabilized after the second round, whereas the detection rate of distal colon cancer decreased until the fourth round in men (from 0.7 to 0.3 per 1000), and the fifth round in women.

CONCLUSIONS

These findings support the notion that FIT screening prevents progression of a subset of advanced adenomas. Screening intensity could be modulated based on results from previous rounds, with a risk-based strategy.

Quality indicators for screening colonoscopy and colonoscopist performance and the subsequent risk of interval colorectal cancer: a systematic review

OBJECTIVE

The objective of this review was to assess the association between quality indicators used to evaluate individual colonoscopist performance and subsequent interval colorectal cancers (CRCs) in patients participating in bowel cancer screening programs.

INTRODUCTION

Colorectal cancer is a leading cause of cancer death. Bowel cancer screening has been shown to reduce CRC mortality and morbidity, and has therefore been introduced in many countries. Endoscopy societies have developed quality assurance guidelines and guidelines on quality indicators for screening colonoscopies. These quality indicators need to be validated against a relevant outcome to assess their value.

INCLUSION CRITERIA

We included studies on screening colonoscopies conducted on participants in a bowel cancer screening program, regardless of comorbidity. Studies on procedures performed on patients with known CRC, hereditary nonpolyposis colorectal cancer or familial adenomatous polyposis were excluded. We also included studies evaluating the quality indicators of withdrawal time (WT), cecal intubation rate (CIR) and adenoma detection rate (ADR). The search did not reveal any studies evaluating the quality indicators polyp retrieval rate and incomplete adenoma resection/incomplete polyp resection. Only studies with interval CRC as an outcome were included (i.e. CRC diagnosed after a negative screening colonoscopy, but before the next recommended examination date).

METHODS

Published studies were searched in: MEDLINE, Embase, Web of Science and CINAHL. Unpublished studies were searched in: OpenGrey and Grey Literature Report. The sources were searched from 1980 to2018. Data were extracted using the JBI critical appraisal checklist for analytical cross sectional studies. A meta-analysis was conducted based on three of the colonoscopist dependent quality indicators: WT, CIR and ADR.

RESULTS

Seven prospective and retrospective cohort studies were included out of 2373 papers identified after duplicates were removed. The included studies were on bowel cancer screening programs with colonoscopy as the primary screening tool, resulting in the inclusion of a total of 616,390 screening colonoscopies performed by 1431 colonoscopists and 2319 subsequent interval CRCs. Six studies were assessed as high-quality studies, and one study was of low quality. The meta-analysis on WT revealed a 61% lower risk of interval CRC among the patients if the mean WT per colonoscopist was >6 minutes as compared to a mean WT of <6 minutes (RR: 0.39 [95% CI: 0.23 - 0.66]). The meta-analysis on CIR revealed a 31% lower risk of interval CRC among the patients if the CIR per colonoscopist was ≥90% as compared to a CIR of <85% (RR: 0.69 [95% CI: 0.56 - 0.83]). One of two meta-analyses on the individual colonoscopist ADR suggested that this should be 15-19%, as compared to an ADR <10% (RR: 0.77 [95% CI: 0.62 - 0.96]), in order to significantly reduce the risk of interval CRC. The other meta-analysis on ADR revealed a significant association between an individual colonoscopist ADR of ≥25% and a lower risk of interval CRC as compared to an ADR of <25% (RR: 0.51 [95% CI: 0.33 - 0.80]). The meta-analyses on WT and CIR showed no heterogeneity concerning the significant results (I = 0.0%). A high variability across studies due to heterogeneity concerning an ADR of ≥20% resulted in an I = 59.9%, and an I = 63.2% for an ADR of ≥25%.

CONCLUSIONS

To minimize the risk of interval CRC, it may be recommended that WT and CIRs are monitored in bowel cancer screening programs, with an optimal individual colonoscopist mean withdrawal time of >6 minutes and a cecal intubation rate of ≥90%. In bowel cancer screening programs using colonoscopy as their primary screening tool, it may be recommended that the individual colonoscopist ADR be 15-19% or better ≥25% to minimize the risk of interval CRC.

Interval colorectal cancers after negative faecal immunochemical test in a 13-year screening programme

OBJECTIVE

To assess faecal immunochemical test sensitivity for cancer in a very large population-based cohort followed up for six rounds with biennial faecal immunochemical test repetition.

METHODS

This study is based on interval colorectal cancers diagnosed in a cohort of subjects aged 50-69 undergoing repeated faecal immunochemical test screening (six rounds) from 2002 to 2015. Test sensitivity was calculated using both the Proportional Interval Cancer Rate and the Interval Cancer Proportion method.

RESULTS

Among 441,647 faecal immunochemical tests (123,347 individuals), 150 interval colorectal cancers were detected after a negative faecal immunochemical test. Interval colorectal cancer incidence rate was 1.87 per 10,000 person-years (95%CI: 1.60-2.20), and it was higher during the second interval year (rate ratio: 1.78; 95%CI: 1.28-2.47), for proximal locations (rate ratio: 3.00; 95%CI: 1.92-4.68), and among 60-71 year old subjects (rate ratio: 2.37; 95%CI: 1.61-3.50). The Proportional Interval Cancer Rate was 13.1%, with an overall faecal immunochemical test sensitivity of 86.9% (95%CI: 84.7-89.0). Sensitivity was lowest at the first round (81.5%; 95%CI: 75.6-86.2), and increased to 91.9% (95%CI: 83.9-96.5) for subsequent rounds. Applying the Interval Cancer Proportion method, sensitivity was 83.9% (95%CI: 81.3-86.2), and it was highest at the first round (89.0%; 95%CI: 85.7-91.6), ranging between 73% and 83.1% at subsequent rounds.

CONCLUSIONS

A faecal immunochemical test sensitivity for cancer higher than 80% resulted in a low incidence of interval colorectal cancers, representing an accurate estimate of one of the major limits of screening programmes. Due to intrinsic biases, the Proportional Interval Cancer Rate and the Interval Cancer Proportion methods generated different trends in faecal immunochemical test sensitivity by screening round.

Proportional incidence of interval colorectal cancer in a large population-based faecal immunochemical test screening programme

BACKGROUND

The European guidelines for quality assurance in colorectal cancer (CRC) screening recommend that interval cancer rate be expressed as a proportion of background incidence rate.

AIM

To determine the crude and adjusted proportional incidence of interval CRC in an Italian regional two-yearly faecal immunochemical test (FIT) screening programme.

METHODS

The programme (year of implementation, 2005) is targeted at over 1,000,000 people aged 50-69 years. The test is a one-sample OC-Sensor (Eiken Chemical Co., Tokyo, Japan). The study covered one-third of the regional area. Excerpts of 434,295 eligible negative FIT records dated 2005-2012 from 193,193 subjects were retrieved from the regional CRC screening data warehouse. By 31 December 2013, the cohort accumulated 198,302 man-years and 235,370 woman-years. Interval CRCs were identified by record-linkage with the local population-based cancer registry. Their number was divided by the expected number, estimated with age-period-cohort models, to obtain the proportional incidence.

RESULTS

The proportional incidence of interval CRC for men and women was, respectively, 0.06 (95% confidence interval (CI), 0.04-0.09) and 0.17 (95% CI, 0.13-0.23) in the first interval year, and 0.21 (95% CI, 0.16-0.26) and 0.28 (95% CI, 0.22-0.36) in the second year.

CONCLUSIONS

The results were acceptable and in line with previous studies.

Impact of temperature and humidity on performance of the fecal immunochemical test for advanced colorectal neoplasia

Although it is known that ambient temperature can affect the diagnostic performance of the fecal immunochemical test (FIT), the impact of other weather parameters, including humidity, on the sensitivity of FIT remains to be further investigated. We aimed to evaluate the impact of ambient temperature and humidity on the performance of FIT for screening for advanced colorectal neoplasia (ACRN). We included asymptomatic individuals who had undergone both screening colonoscopy and FIT. The diagnostic performance of FIT, including its sensitivity, was analyzed according to the ambient temperature and humidity on the day that FIT was performed. Temperature and humidity were divided into five levels. Among 35,461 participants, 589 (1.7%) had ACRN. The positivity rate of FIT was lower at ≥24 °C (3.1%) than at <0 °C (3.9%), 0–8 °C (4.3%), and 8–16 °C (3.9%). It was also lower at 80–90% humidity (3.1%) than at < 60% humidity (3.9%). Multivariable analysis showed that high ambient temperature (≥24 °C) with high ambient humidity (≥80%) was associated with a low positivity rate of FIT (odds ratio [OR] 0.62, 95% confidence interval [CI] 0.44–0.86). Sensitivity tended to decrease at high ambient temperature (<24 °C vs. ≥24 °C; 20.8% vs. 14.6%, P = 0.110) and was significantly lower at high ambient humidity (<80% vs. ≥80%; 21.0% vs. 12.5%, P = 0.044). The multivariable analysis also showed that high ambient humidity was independently associated with low sensitivity of FIT (OR 0.54, 95% CI 0.28–0.96). In conclusion, high ambient humidity decreased the sensitivity, while high ambient temperature along with high ambient humidity decreased the positivity rate of FIT.

Incidence of faecal occult blood test interval cancers in population-based colorectal cancer screening: a systematic review and meta-analysis

OBJECTIVE

Faecal immunochemical tests (FITs) are replacing guaiac faecal occult blood tests (gFOBTs) for colorectal cancer (CRC) screening. Incidence of interval colorectal cancer (iCRC) following a negative stool test result is not yet known. We aimed to compare incidence of iCRC following a negative FIT or gFOBT.

DESIGN

We searched Ovid Medline, Embase, Cochrane Library, Science Citation Index, PubMed and Google Scholar from inception to 12 December 2017 for citations related to CRC screening based on stool tests. We included studies on FIT or gFOBT iCRC in average-risk screening populations. Main outcome was pooled incidence rate of iCRCs per 100 000 person-years (p-y). Pooled incidence rates were obtained by fitting random-effect Poisson regression models.

RESULTS

We identified 7 426 records and included 29 studies. Meta-analyses comprised data of 6 987 825 subjects with a negative test result, in whom 11 932 screen-detected CRCs and 5 548 gFOBT or FIT iCRCs were documented. Median faecal haemoglobin (Hb) positivity cut-off used was 20 (range 10-200) µg Hb/g faeces in the 17 studies that provided FIT results. Pooled incidence rates of iCRC following FIT and gFOBT were 20 (95% CI 14 to 29; I²=99%) and 34 (95% CI 20 to 57; I²=99%) per 100 000 p-y, respectively. Pooled incidence rate ratio of FIT versus gFOBT iCRC was 0.58 (95% CI 0.32 to 1.07; I²=99%) and 0.36 (95% CI 0.17 to 0.75; I²=10%) in sensitivity analysis. For every FIT iCRC, 2.6 screen-detected CRCs were found (ratio 1:2.6); for gFOBT, the ratio between iCRC and screen-detected CRC was 1:1.2. Age below 60 years and the third screening round were significantly associated with a lower iCRC rate.

CONCLUSION

A negative gFOBT result is associated with a higher iCRC incidence than a negative FIT. This supports the use of FIT over gFOBT as CRC screening tool.

Interval cancers after negative immunochemical test compared to screen and non-responders' detected cancers in Slovenian colorectal cancer screening programme

Background

We assessed the incidence and characteristics of interval cancers after faecal immunochemical occult blood test and calculated the test sensitivity in Slovenian colorectal cancer screening programme.

Patients and methods

The analysis included the population aged between 50 to 69 years, which was invited for screening between April 2011 and December 2012. The persons were followed-up until the next foreseen invitation, in average for 2 years. The data on interval cancers and cancers in non-responders were obtained from cancer registry. Gender, age, years of schooling, the cancer site and stage were compared among three observed groups. We used the proportional incidence method to calculate the screening test sensitivity.

Results

Among 502,488 persons invited for screening, 493 cancers were detected after positive screening test, 79 interval cancers after negative faecal immunochemical test and 395 in non-responders. The proportion of interval cancers was 13.8%. Among the three observed groups cancers were more frequent in men (p = 0.009) and in persons aged 60+ years (p < 0.001). Comparing screen detected and cancers in non-responders with interval cancers more interval cancers were detected in persons with 10 years of schooling or more (p = 0.029 and p = 0.001), in stage III (p = 0.027) and IV (p < 0.001), and in right hemicolon (p < 0.001). Interval cancers were more frequently in stage I than non-responders cancers (p = 0.004). Test sensitivity of faecal immunochemical test was 88.45%.

Conclusions

Interval cancers in Slovenian screening programme were detected in expected proportions as in similar programmes. Test sensitivity was among the highest when compared to similar programmes and was accomplished using test kit for two stool samples.

Determining the Sensitivity of Transrectal Ultrasonography on a Consecutive Series of Prostate Cancers in a Clinical and Screening Setting

Purpose

To evaluate the sensitivity at transrectal ultrasonography (TRUS) for prostate cancer.

Material

A consecutive series of 170 prostate cancers identified by matching local cancer registry and TRUS archives at the Centro per lo Studio e la Prevenzione Oncologica of Florence.

Method

TRUS sensitivity was determined as the ratio of TRUS positive to total prostate cancers occurring at different intervals from TRUS date. Univariate and multivariate analyses of sensitivity determinants were performed.

Results

Sensitivity at 6 months, 1, 2 and 3 years after the test was 94.1% (95% Cl, 90-98), 89.8% (95% Cl, 85-95), 80.4% (95% Cl, 74-87) and 74.1% (95% Cl, 68-81%), respectively. A higher sensitivity (statistically significant) of TRUS was observed only if digital rectal examination was suspicious, whereas no association to sensitivity was observed for age, prostate-specific antigen or prostate-specific antigen density.

Conclusions

The study provided a reliable estimate of TRUS sensitivity, particularly reliable being checked against a cancer registry: observed sensitivity was high, at least of the same magnitude of other cancer screening tests. TRUS, which is known to allow for considerable diagnostic anticipation and is more specific than prostate-specific antigen, might still be considered for its contribution to a screening approach.

Overall evaluation of an immunological latex agglutination system for fecal occult blood testing in the colorectal cancer screening program of Florence

Several immunological fecal occult blood tests (FOBT) are currently available for colorectal cancer (CRC) screening. We compared the HM Jack (Jack) (Kiowa, Japan), with the OC-Hemodia (OC) (Eiken, Japan) in use in the Florence screening program. Aims of the study were: (i) to investigate the diagnostic performance and the best cutoff value for Jack; (ii) to evaluate the handiness of sampling tubes; (iii) to compare costs. A total of 5,044 subjects were screened with both tests. Sampling tube investigation was performed running each sample on both instruments. A number of 352 subjects positive for at least one test (175 OC, 310 Jack) were selected for further investigations, while 46 subjects refused further assessments. Analysis of costs related to the assessment phase was performed on the basis of Tuscany region's fares. Amongst the 306 subjects investigated, 9 CRC and 67 advanced adenomas (AdA) were detected. Detection rates (DR) were 1.4‰ for CRC and 9.6‰ for AdA. After Jack cutoff optimization, DR for CRC+AdA resulted in 11.1‰ for OC and 13.3‰ for Jack (p=0.041). Sensitivity of the methods was 73.7 for OC and 88.2 for Jack; specificity was 97.6 for OC and 96.0 for Jack, resulting in an increase of the required assessments from 3.5% to 5.1%. No differences were observed between sampling methods. Despite the lower specificity of Jack, its greater sensitivity makes the method attractive for screening programs. An increase of the costs of 30% for every subject investigated for pathological lesion (CRC+AdA) may be thus foreseen.

Age-adapted Variation in Screening Interval of Fecal Immunochemical Test May Improve its Participation and Colonoscopy Acceptance

GOALS

We determined appropriate intervals for administering the fecal immunochemical test (FIT) and performance outcomes in an Asian national colorectal cancer (CRC) screening program.

BACKGROUND

The optimal interval for FIT in CRC screening is unclear, especially in Asian populations.

STUDY

Between January 2009 and December 2015, 13,480 individuals aged 50 years or older with an initial negative FIT result underwent 2 rounds of FIT screening at intervals of 1 (annual group, 5333), 2 (biennial group, 7363), or 3 years (triennial group, 784). Positive rates of FIT, colonoscopy acceptance, colonoscopy findings, and detection rates for CRC and advanced neoplasia were compared according to FIT intervals.

RESULTS

The overall positivity rate of FIT in the second screening round was significantly higher in men and in older subjects than in the entire sample. Younger subjects were less likely to undergo annual FIT (36.0% vs. 46.4%, P<0.001). The colonoscopy acceptance rate was decreased in the biennial and triennial groups compared with an annual group among younger subjects (odds ratio, 0.56; 95% confidence interval, 0.33-0.95 for the biennial group vs. odds ratio, 0.19; 95% confidence interval, 0.03-1.37 for the triennial group). Detection rates for CRC and advanced neoplasia in the second round were significantly higher and accompanied by increased FIT screening intervals in older, but not younger subjects.

CONCLUSIONS

Age-adapted variation in FIT screening intervals, such as annual screening for elderly subjects and biennial screening for younger subject, may improve FIT participation and colonoscopy acceptance.

Incidence of interval cancers in faecal immunochemical test colorectal screening programmes in Italy

Objective

In Italy, colorectal screening programmes using the faecal immunochemical test from ages 50 to 69 every two years have been in place since 2005. We aimed to measure the incidence of interval cancers in the two years after a negative faecal immunochemical test, and compare this with the pre-screening incidence of colorectal cancer.

Methods

Using data on colorectal cancers diagnosed in Italy from 2000 to 2008 collected by cancer registries in areas with active screening programmes, we identified cases that occurred within 24 months of negative screening tests. We used the number of tests with a negative result as a denominator, grouped by age and sex. Proportional incidence was calculated for the first and second year after screening.

Results

Among 579,176 and 226,738 persons with negative test results followed up at 12 and 24 months, respectively, we identified 100 interval cancers in the first year and 70 in the second year. The proportional incidence was 13% (95% confidence interval 10–15) and 23% (95% confidence interval 18–25), respectively. The estimate for the two-year incidence is 18%, which was slightly higher in females (22%; 95% confidence interval 17–26), and for proximal colon (22%; 95% confidence interval 16–28).

Conclusion

The incidence of interval cancers in the two years after a negative faecal immunochemical test in routine population-based colorectal cancer screening was less than one-fifth of the expected incidence. This is direct evidence that the faecal immunochemical test-based screening programme protocol has high sensitivity for cancers that will become symptomatic.

Interval cancers in a guaiac-based colorectal cancer screening programme: Consequences on sensitivity

Objective

To evaluate interval cancers in the population-based colorectal cancer screening programme of Stockholm/Gotland, Sweden.

Methods

From 2008, individuals aged 60–69 were invited to colorectal cancer screening using biennial guaiac-based faecal occult blood test (Hemoccult®). Interval cancers, defined as colorectal cancer among participants not diagnosed by the screening programme but registered in the Swedish cancer register, were evaluated by cross-checking the screening histories for all cancers in the region 2008–2012.

Results

Of 203,848 individuals from nine different birth cohorts who participated (∼60%), 4530 (2.2%) tested positive. All invited individuals were followed up for 24 months after invitation. The cancer register reported 557 colorectal cancer, 219 (39.3%) screen-detected cancers and 338 (60.7%) interval cancers, generating both test- and episode sensitivities of approximately 40% and an interval cancer-rate of 17.1/10,000 tests. Among individuals with positive tests without colorectal cancer diagnosed at work-up colonoscopy, 37 interval cancers (10.9%) occurred. There was statistically significant lower sensitivity in women, ranging 22.4–32.2%, compared with 43.2–52.0% in men. Age-group and tumour location were not strongly correlated to screen-detected cancer rates. The programme sensitivity increased by year (20.3–25.0%), with successively more colorectal cancers diagnosed within the expanding programme (11.6–16.2%).

Conclusion

Interval cancer is a quality indicator of a screening programme. As the interval cancer-rate determined in a well-organized population-based screening programme was actually higher than the screen-detected cancer rate, a change to a more sensitive screening test is indicated. The lower screen-detected cancers among women, and compliance and quality of work-up colonoscopies also need attention.

Performance of a quantitative fecal immunochemical test in a colorectal cancer screening pilot program: a prospective cohort study

BACKGROUND

British Columbia undertook a colorectal cancer screening pilot program in 3 communities. Our objective was to assess the performance of 2-specimen fecal immunochemical testing in the detection of colorectal neoplasms in this population-based screening program.

METHODS

A prospective cohort of asymptomatic, average-risk people aged 50 to 74 years completed 2 quantitative fecal immunochemical tests every 2 years, with follow-up colonoscopy if the result of either test was positive. Participant demographics, fecal immunochemical test results, colonoscopy quality indicators and pathology results were recorded. Non-screen-detected colorectal cancer that developed in program participants was identified through review of data from the BC Cancer Registry.

RESULTS

A total of 16 234 people completed a first round of fecal immunochemical testing, with a positivity rate of 8.6%; 5378 (86.0% of eligible participants) completed a second round before the end of the pilot program, with a positivity rate of 6.7%. Of the 1756 who had a positive test result, 1555 (88.6%) underwent colonoscopy. The detection rate of colorectal cancer was 3.5 per 1000 participants. The positive predictive value of the fecal immunochemical test was 4.9% (95% confidence interval [CI] 3.8%-6.0%) for colorectal cancer, 35.0% (95% CI 32.5%-37.2%) for high-risk polyps and 62.0% (95% CI 59.6%-64.4%) for all neoplasms. The number needed to screen was 283 to detect 1 cancer, 40 to detect 1 high-risk polyp and 22 to detect any neoplasm.

INTERPRETATION

Screening every 2 years with a 2-specimen fecal immunochemical test surpassed the current benchmark for colorectal cancer detection in population-based screening. This study has implications for other jurisdictions planning colorectal cancer screening programs.

[Interval cancers and episode sensitivity in population-based screening programmes for colorectal cancer: a systematic review]

OBJECTIVE

To describe interval cancers (IC) and the sensitivity of colorectal cancer (CRC) screening programmes.

METHODS

A systematic review of the literature was conducted through a MEDLINE (PubMed) search. The search strategy combined the terms 'interval cancer', 'false negative', 'mass screening', 'screening' 'early detection of cancer', 'colorectal cancer' and 'bowel cancer'. Inclusion criteria consisted of population-based screening programmes, original articles written in English or Spanish and publication dates between 1999/01/01 and 2015/02/28. A narrative synthesis of the included articles was performed detailing the characteristics of the screening programmes, the IC rate, and the information sources used in each study.

RESULTS

Thirteen articles were included. The episode sensitivity of CRC screening programmes ranged from 42.2% to 65.3% in programmes using the guaiac test and between 59.1% and 87.0% with the immunochemical test. We found a higher proportion of women who were diagnosed with IC and these lesions were mainly located in the proximal colon.

CONCLUSION

There is wide variability in the IC rate in CRC programmes. To ensure comparability between programmes, there is a need for consensus on the working definition of IC and the methods used for their identification and quantification.

Impact of Preanalytical Factors on Fecal Immunochemical Tests: Need for New Strategies in Comparison of Methods

Background

Harmonization of fecal immunochemical tests for hemoglobin (FIT-Hb) is crucial to compare clinical outcomes in screening programs. The lack of reference materials and standard procedures does not allow the use of usual protocols to compare methods. We propose 2 protocols, based on artificial biological samples (ABS), to discriminate preanalytical and analytical variation and investigate clinical performances. The protocols were used to compare 2 FIT systems available on European markets: the OC-Sensor Diana (Eiken, Tokyo, Japan) and HM-JACKarc (Kyowa-Medex, Tokyo, Japan).

Methods

ABS were obtained adding Hb to Hb-free feces. In the first procedure, 35 ABS were collected for each collection device and analyzed on both systems. In the second, 188 ABS (106 positive and 82 negative) were ­collected and tested on the specific systems. Passing-Bablock (PB), Pearson's correlation coefficients (R) and Bland-Altman difference analysis were used to compare data.

Results

PB, R and mean standard errors for Bland-Altman analysis (Diana vs. Arc) results were 0.93x-0.56: R = 0.97 and 19%; and 1.09x + 5.60: R = 0.96 and −18%; for Diana and Arc devices, respectively. No correlations and no difference in positive/negative assessment were observed with the second protocol.

Conclusions

A good correlation was observed in comparing data generated using collection devices on the 2 systems. Manufacturers have developed different sample collection procedures for feces: therefore, data from different systems cannot easily be compared. Adoption of protocols to discriminate preanalytical and analytical variation would be a significant contribution to harmonization of FIT, facilitating data comparison and information acquisition for sample collection strategy and effect of buffers on systems.

The Diagnostic Accuracy of the M2 Pyruvate Kinase Quick Stool Test--A Rapid Office Based Assay Test for the Detection of Colorectal Cancer

Background

M2 pyruvate kinase (M2PK) is an oncoprotein secreted by colorectal cancers in stools. This the first report on the accuracy of a rapid stool test in the detection of colorectal cancer (CRC).

Objective

To determine the sensitivity, specificity and positive and negative predictive value of a rapid, point of care stool test M2 PK- the M2PK Quick.

Methods

Consecutive cases of endoscopically diagnosed and histological proven CRC were recruited. Stools were collected by patients and tested with the immunochromatographic M2PK Quick Test (Schebo Biotech AC, Giessen, Germany). Controls were consecutively chosen from patients without any significant colorectal or gastrointestinal disease undergoing colonoscopy. CRC was staged according to the AJCC staging manual (7^th Edition) and location of tumor defined as proximal or distal.

Results

The sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy were: 93%, 97.5%, 94.9%, 96.5% and 96.0% respectively. The positive predictive value for proximal tumors was significantly lower compared to distal tumors. No differences were seen between the different stages of the tumor.

Conclusions

The M2-PK Quick, rapid, point-of-care test is a highly accurate test in the detection of CRC. It is easy and convenient to perform and a useful diagnostic test for the detection of CRC in a clinical practice setting.

Difference in performance of fecal immunochemical tests with the same hemoglobin cutoff concentration in a nationwide colorectal cancer screening program

BACKGROUND & AIMS

We investigated whether 2 quantitative fecal immunochemical tests (FITs) with the same cutoff concentration of fecal hemoglobin perform equivalently in identifying patients with colorectal cancer (CRC).

METHODS

A total of 956,005 Taiwanese subjects, 50 to 69 years old, participated in a nationwide CRC screening program to compare results from 2 FITs; 78% were tested using the OC-Sensor (n = 747,076; Eiken Chemical Co, Tokyo, Japan) and 22% were tested using the HM-Jack (n = 208,929; Kyowa Medex Co Ltd, Tokyo, Japan), from 2004 through 2009. The cutoff concentration for a positive finding was 20 μg hemoglobin/g feces, based on a standardized reporting unit system. The tests were compared using short-term and long-term indicators of performance.

RESULTS

The OC-Sensor test detected CRC in 0.21% of patients, with a positive predictive value of 6.8%. The HM-Jack test detected CRC in 0.17% of patients, with a positive predictive value of 5.2%. The rate of interval cancer rate was 30.7/100,000 person-years among subjects receiving the OC-Sensor test and 40.6/100,000 person-years among those receiving the HM-Jack test; there was significant difference in test sensitivity (80% vs 68%, P = .005) that was related to the detectability of proximal CRC. After adjusting for differences in city/county, age, sex, ambient temperature, and colonoscopy quality, significant differences were observed between the tests in the positive predictive value for cancer detection (adjusted relative risk = 1.29; 95% confidence interval, 1.14-1.46) and the rates of interval cancer (0.75; 95% confidence interval, 0.62-0.92). Although each test was estimated to reduce CRC mortality by approximately 10%, no significant difference in mortality was observed when the 2 groups were compared.

CONCLUSIONS

Different brands of quantitative FITs, even with the same cutoff hemoglobin concentration, perform differently in mass screening. Population-level data should be gathered to verify the credibility of quantitative laboratory findings.

Guaiac faecal occult blood test performance at initial and repeat screens in the English Bowel Cancer Screening Programme

BACKGROUND

In many countries, screening for colorectal cancer (CRC) relies on repeat testing using the guaiac faecal occult blood test (gFOBT). This study aimed to compare gFOBT performance measures between initial and repeat screens.

METHODS

Data on screening uptake and outcomes from the English Bowel Cancer Screening Programme (BCSP) for the years 2008 and 2011 were used. An existing CRC natural history model was used to estimate gFOBT sensitivity and specificity, and the cost-effectiveness of different screening strategies.

RESULTS

The gFOBT sensitivity for CRC was estimated to decrease from 27.35% at the initial screen to 20.22% at the repeat screen. Decreases were also observed for the positive predictive value (8.4-7.2%) and detection rate for CRC (0.19-0.14%). Assuming equal performance measures for both the initial and repeat screens led to an overestimate of the cost effectiveness of gFOBT screening compared with the other screening modalities.

CONCLUSIONS

Performance measures for gFOBT screening were generally lower in the repeat screen compared with the initial screen. Screening for CRC using gFOBT is likely to be cost-effective; however, the use of different screening modalities may result in additional benefits. Future economic evaluations of gFOBT should not assume equal sensitivities between screening rounds.

A new insight into fecal hemoglobin concentration-dependent predictor for colorectal neoplasia

We sought to assess how much of the variation in incidence of colorectal neoplasia is explained by baseline fecal hemoglobin concentration (FHbC) and also to assess the additional predictive value of conventional risk factors. We enrolled subjects aged 40 years and over who attended screening for colorectal cancer with the fecal immunochemical test (FIT) in Keelung community-based integrated screening program. The accelerated failure time model was used to train the clinical weights of covariates in the prediction model. Datasets from two external communities were used for external validation. The area under curve (AUC) for the model containing only FHbC was 83.0% (95% CI: 81.5-84.4%), which was considerably greater than the one containing only conventional risk factors (65.8%, 95% CI: 64.2-67.4%). Adding conventional risk factors did not make significant additional contribution (p = 0.62, AUC = 83.5%, 95% CI: 82.1-84.9%) to the predictive model with FHbC only. Males showed a stronger linear dose-response relationship than females, yielding gender-specific FHbC predictive models. External validation confirms these results. The high predictive ability supported by a dose-dependent relationship between baseline FHbC and the risk of developing colorectal neoplasia suggests that FHbC may be useful for identifying cases requiring closer postdiagnosis clinical surveillance as well as being an early indicator of colorectal neoplasia risk in the general population. Our findings may also make contribution to the development of the FHbC-guided screening policy but its pros and cons in connection with cost and effectiveness of screening should be evaluated before it can be applied to population-based screening for colorectal cancer.

Sensitivity of endoscopic screening for gastric cancer by the incidence method

Although radiographic screening for gastric cancer has been conducted in Japan, it is anticipated that endoscopy will become a new screening method because of its high detection rate. The sensitivities of endoscopic and radiographic screening were calculated by the detection method and the incidence method based on the results of community-based screening in Japan. There were 56,676 screenings for gastric cancer using endoscopy and radiography from April 2002 to March 2007 in Yonago, Japan. The target age group was from 40 to 79 years. Screen-detected and interval cancers were investigated based on a screening database linked to the Tottori Cancer Registry. All gastric cancers diagnosed within 1 year after a negative screen were considered interval cancers. Based on the screening history, these were divided into prevalence screening and incidence screening. Prevalence screenings included 7,388 for endoscopic screening and 5,410 for radiographic screening, whereas incidence screenings included 18,021 for endoscopic screening and 11,417 for radiographic screening. The sensitivity of prevalence screening calculated by the incidence method was 0.886 (95% confidence interval [CI] = 0.698-0.976) for endoscopic screening and 0.831 (95% CI = 0.586-0.964) for radiographic screening; however, the difference was not significant (p = 0.626). The sensitivity of incidence screening calculated by the incidence method was 0.954 (95% CI = 0.842-0.994) for endoscopic screening and 0.855 (95% CI = 0.637-0.970) for radiographic screening (p = 0.177). Endoscopic screening for gastric cancer had a higher sensitivity than radiographic screening by the incidence method in both screening rounds. However, further study is needed to evaluate mortality reduction and to estimate overdiagnosis with endoscopic screening for gastric cancer.

Immunological faecal occult blood testing: a discriminatory test to identify colorectal cancer in symptomatic patients

INTRODUCTION

Current investigation for patients with colorectal symptoms without overt rectal bleeding is undertaken by colonoscopy or by flexible sigmoidoscopy and barium enema. A large majority of patients do not have colorectal cancer. There exists no instant, objective measure to discriminate patients who are likely to have colorectal cancer and therefore require expedient investigation.

AIM

To evaluate the sensitivity and specificity of immunological faecal occult blood testing (FOBT) in patients with colorectal symptoms without overt rectal bleeding.

METHODS

Consecutive patients referred for urgent colonic investigation, were prospectively studied. A faecal sample was obtained from each one and subjected to immunological FOB which tested either negative or positive. All patients then underwent complete colonic imaging. The correlation between FOBT status and results from colonic imaging was studied.

RESULTS

Of 126 tested, thirty patients (26.8%) were FOBT positive. One hundred and twelve patients underwent complete colonic imaging. In the FOBT positive group colonic imaging identified 17 cases of histologically proven adenocarcinoma, 1 recurrent squamous cell carcinoma of anus, 1 adenomatous polyp, 6 cases of diverticulosis, and no pathology in 5 cases. In the 82 FOBT negative patients, no cancers were found. Overall the Immunological Faecal Occult Blood Test was found to have 100% sensitivity and 86.3% specificity.

CONCLUSION

Immunological faecal occult blood testing is a sensitive and specific test in identifying colorectal cancer and may be useful in identifying those patients who warrant urgent investigation. Routine clinical application may be useful in the allocation of resources.

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

PURPOSE

Fecal immunochemical tests (FITs) have been developed to address analytical problems inherent in the older guaiac-based fecal occult blood tests (g-FOBTs). Our aim was to compare the performance characteristics of one g-FOBT (Hemoccult II) and two FITs (the Hemoccult ICT and MagStream HemSp) relative to colonoscopy for the detection of colorectal cancer and significant precursor lesions. We also examined whether a 1-day collection strategy would negatively impact test diagnostic performance.

METHODS

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

RESULTS

One thousand seventy-five individuals were enrolled (mean age 56.3 years, 53.8 % females). Using colonoscopy as the gold standard, the sensitivity for screen-relevant neoplasm was determined for Hemoccult II (7.2, 95 % CI: 1.1-13.4), Hemoccult ICT (23.2 %: 13.2-33.1), and MagStream HemSp using 67 μg/gram stool as the cut-off (23.2 %: 13.2-33.1). The Magstream HemSp, using a cut-off threshold of 30 μg/gram stool, had the lowest specificity at 87.6 % (85.4-89.6), while the Hemoccult II had the highest at 98.8 % (98.1-99.5). Single-day stool testing reduced the false-positive rates of all tests without significantly reducing the sensitivity.

CONCLUSION

We found that FITs have a significantly increased sensitivity but reduced specificity for screen-relevant neoplasm compared to g-FOBT using colonoscopy as the gold standard. Optimal threshold levels for hemoglobin detection depend on the desired trade off between sensitivity and false-positive rate. Single-day testing with an FIT may be an option to enhance population compliance with screening.

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.

Cost-effectiveness of mass screening for colorectal cancer: choice of fecal occult blood test and screening strategy

BACKGROUND

Colorectal cancer is a major cause of mortality. This gives high public health priority to mass screening using a noninvasive, fecal occult blood test of asymptomatic individuals. A positive test selects those who should undergo colonoscopy to ensure early detection of colorectal cancer. Guaiac fecal occult blood test has low sensitivity. Automated immunochemical tests that measure the fecal human hemoglobin concentration are more sensitive and can be simplified as a 1- to 3-sample format with optimum cutoff points.

OBJECTIVE

The aim was to improve the sensitivity of the test by choosing an accurate format (1- to 3-sample and optimum hemoglobin concentration) while maintaining acceptable specificity and avoiding alteration of the screening program in terms of quality of life and economic outputs.

METHODS

We used a Markov model to estimate the cost-effectiveness of a screening program for a population of 100,000 asymptomatic individuals by use of immunological fecal tests with different cutoffs, leading to different sensitivity/specificity ratios, and to compare its incremental cost-effectiveness ratio compared with the guaiac fecal test program.

RESULTS

The results suggest that a 3-sample immunological test with 50 ng/mL as a positive cutoff is cost-effective. It provides more asymptomatic cancer detection without significantly increasing normal colonoscopies.

CONCLUSION

This format should be prospectively evaluated in mass screening.

Performance improvements of stool-based screening tests

Stool testing is a widely accepted, non-invasive, technique for colorectal cancer (CRC) screening. Guaiac-based faecal occult blood test (gFOBT) screening has been proven to decrease CRC-related mortality; however gFOBT is hampered by a low sensitivity. Faecal immunochemical tests (FITs) have several advantages over gFOBT. First of all, FIT has a better sensitivity and higher uptake. Furthermore, the quantitative variant of the FIT allows choices on cut-off level for test-positivity according to colonoscopy resources available, personal risk profile, and/or intended detection rate in the screened population. Stool-based DNA (sDNA) tests aiming at the detection of specific DNA alterations may improve detection of CRC and adenomas compared to gFOBT screening, but large-scale population based studies are lacking. This review focuses on factors influencing test performance of those three stool based screening tests.

Cost-effectiveness of colorectal cancer screening - an overview

There are several modalities available for a colorectal cancer (CRC) screening program. When determining which CRC screening program to implement, the costs of such programs should be considered in comparison to the health benefits they are expected to provide. Cost-effectiveness analysis provides a tool to do this. In this paper we review the evidence on the cost-effectiveness of CRC screening. Published studies universally indicate that when compared with no CRC screening, all screening modalities provide additional years of life at a cost that is deemed acceptable by most industrialized nations. Many recent studies even find CRC screening to be cost-saving. However, when the alternative CRC screening strategies are compared against each other in an incremental cost-effectiveness analysis, no single optimal strategy emerges across the studies. There is consensus that the new technologies of stool DNA testing, computed tomographic colonography and capsule endoscopy are not yet cost-effective compared with the established CRC screening tests.

Diagnostic accuracy of immunochemical versus guaiac faecal occult blood tests for colorectal cancer screening

BACKGROUND

Immunochemical tests show important advantages over chemical-based faecal occult blood tests (FOBT) for colorectal cancer (CRC) screening, but comparison studies are limited. This study was performed to compare the accuracy of a sensitive immunochemical test with the guaiac test for detecting significant neoplasia (advanced adenomas and CRC) in an average-risk population.

METHODS

A random sample of 2288 asymptomatic subjects 50-79 years of age was prospectively included. Participants received three cards of the guaiac test, one sample of a latex-agglutination test (haemoglobin cut-off 50 ng/ml), and an invitation to undergo colonoscopy. Test sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated in 1756 compliers.

RESULTS

Immunochemical and guaiac tests were positive in 143 (8.1%) and 62 (3.5%) subjects, respectively. Complete colonoscopy, performed in 402 participants (158 FOBT+ and 244 FOBT-), detected 14 (0.8%) patients with CRC and 49 (2.8%) with advanced adenomas. The immunochemical and guaiac tests for significant colorectal neoplasia showed sensitivities of 61% versus 23.8%, specificities of 95.1% versus 97.7%, PPVs of 43.4% versus 39.0%, and NPVs of 97.5% versus 95.4%, respectively. Proximal significant neoplasms were more frequently detected with the immunochemical test (85% vs. 15%) The relative risk for detecting significant neoplasia was superior in patients with a positive immunochemical test (RR 16.93; CI 7.94-36.10) than with a positive guaiac test (RR 3.34; CI 2.17-5.15).

CONCLUSION

A sensitive immunochemical test is markedly superior to the guaiac test for detecting significant colorectal neoplasia, and should be considered the first-choice FOBT for CRC screening in the average-risk population.

Cost-effectiveness analysis of the optimal threshold of an automated immunochemical test for colorectal cancer screening: performances of immunochemical colorectal cancer screening

BACKGROUND

Most industrialized countries, including France, have undertaken to generalize colorectal cancer screening using guaiac fecal occult blood tests (G-FOBT). However, recent researches demonstrate that immunochemical fecal occult blood tests (I-FOBT) are more effective than G-FOBT. Moreover, new generation I-FOBT benefits from a quantitative reading technique allowing the positivity threshold to be chosen, hence offering the best balance between effectiveness and cost. We aimed at comparing the cost and the clinical performance of one round of screening using I-FOBT at different positivity thresholds to those obtained with G-FOBT to determine the optimal cut-off for I-FOBT.

METHODS

Data were derived from an experiment conducted from June 2004 to December 2005 in Calvados (France) where 20,322 inhabitants aged 50-74 years performed both I-FOBT and G-FOBT. Clinical performance was assessed by the number of advanced tumors screened, including large adenomas and cancers. Costs were assessed by the French Social Security Board and included only direct costs.

RESULTS

Screening using I-FOBT resulted in better health outcomes and lower costs than screening using G-FOBT for thresholds comprised between 75 and 93 ng/ml. I-FOBT at 55 ng/ml also offers a satisfactory alternative to G-FOBT, because it is 1.8-fold more effective than G-FOBT, without increasing the number of unnecessary colonoscopies, and at an extra cost of 2,519 euros per advanced tumor screened.

CONCLUSIONS

The use of an automated I-FOBT at 75 ng/ml would guarantee more efficient screening than currently used G-FOBT. Health authorities in industrialized countries should consider the replacement of G-FOBT by an automated I-FOBT test in the near future.

Cost-effectiveness of screening for colorectal cancer in France using a guaiac test versus an immunochemical test

Objectives: The aim of this study was to compare the cost and the effectiveness of two biennial fecal occult blood screening tests for colorectal cancer: a guaiac nonrehydrated test (G-FOBT) and an immunochemical test (I-FOBT) with the absence of screening.

Methods: A Markov model was developed to compare these strategies in a general population of subjects aged 50 to 74 over a 20-year period.

Results: Compared with the absence of screening, G-FOBT and I-FOBT were associated with a decrease in colorectal cancer mortality of 17.4 percent and 25.2 percent, respectively. With regard to cost-effectiveness, expressed as cost per life-year gained, I-FOBT was the most effective and most costly alternative. Compared with no screening, G-FOBT and I-FOBT presented similar discounted incremental cost-effectiveness ratios: €2,739 and €2,819 respectively per life-year gained. When compared with G-FOBT, I-FOBT presented an incremental cost-effectiveness ratio of €2,988 per life-year gained. Sensitivity analyses showed the strong influence of the I-FOBT lead time, of the participation rate to screening for I-FOBT, and of the purchase price of the I-FOBT on the discounted incremental cost-effectiveness ratios.

Conclusions: Compared with the absence of screening and with G-FOBT, the biennial two-stool immunochemical test can be considered a promising method for mass screening for colorectal cancer.

[Improvement in screening for colorectal cancer associated with the use of immunochemical faecal occult blood test]

Faecal occult blood tests (FOBT) have been established as the most relevant procedure for colorectal cancer screening in the general average risk population. Immunochemical FOBT consists in monoclonal antibodies reacting with the globin of the haemoglobin. These tests provide higher performances than traditional guaiac tests. They do not need any diet restriction and their analytic sensitivity is higher. An increasing number of papers suggest that their acceptance and clinical performances in the general population are more satisfactory than the guaiac test. The use of automated reading allowed to cut the process price making it similar to the guaiac test. The providing of quantitative measure of haemoglobin allows to choose the positivity threshold associated with the best balance between sensitivity, specificity and positivity rate. Comparative studies conducted in France suggest the use of a positivity threshold allowing an increase in both sensitivity and specificity compared to the guaiac tests.

[Chemical or immunological tests for the detection of fecal occult blood in colorectal cancer screening?]

Colorectal cancer (CRC) can be prevented by screening programs in the population at average risk (men and women aged between 50 and 74 years) and at high risk (first degree relatives, CRC hereditary syndromes and chronic inflammatory bowel disease). Early CRC (with submucosal invasion) and advanced adenomas (size > or =10mm, with severe dysplasia or >20% villous component) produce intermittent microscopic blood losses that can be detected through chemical and immunological testing for fecal occult blood (C-FOBT and I-FOBT). Among the screening strategies in the population at average risk, annual or biannual fecal occult blood testing is the most widely used due to its non-invasiveness and low cost. Four randomized clinical trials have shown that annual or biannual screening with guaiac-based tests (C-FOBT) reduces overall mortality due to CRC by 16% and CRC incidence by 20% and 17% respectively. However, these tests have major drawbacks, especially their low sensitivity in detecting early CRC and advanced adenoma, their lack of specificity in detecting human hemoglobin (Hb), and their high fecal Hb detection threshold (>300microgHb/gfeces). In the last few years, major developments have occurred in immunological tests (I-FOBT), based on an antigen-antibody reaction that specifically detects human Hb, and these tests are currently available as an alternative to C-FOBT. Their main advantages are as follows: firstly, I-FOBT specifically detect human Hb in stools and at much lower levels (40-300microgHb/gfeces) than C-FOBT; secondly, automated analysis avoids subjectivity in reading qualitative tests and allows large population groups to be studied in a short time, making I-FOBT ideal for population-based screening; thirdly, I-FOBT fairly accurately selects individuals for colonoscopy so that approximately half of patients with an I-FOBT test show clinically significant colorectal neoplasia (advanced adenoma or invasive CRC); fourthly, the cut-off point for fecal Hb detection can be modified, depending on the availability of endoscopic resources; fifthly, when cut-off points for fecal Hb of 50-150microgHb/gfeces are used, more than twice the number of CRC and advanced adenomas are detected than with C-FOBT, with a reasonable false-positive rate; and sixthly, I-FOBT are better accepted by the population due to their simplicity and ease of use, increasing participation in screening programs. For all these reasons, the current recommendation is that the new quantitative I-FOBT tests replace C-FOBT tests when the strategy of population-based screening through annual or biannual fecal occult blood testing is considered.

Screening for colorectal cancer: random comparison of guaiac and immunochemical faecal occult blood testing at different cut-off levels

Immunochemical faecal occult blood testing (FIT) provides quantitative test results, which allows optimisation of the cut-off value for follow-up colonoscopy. We conducted a randomised population-based trial to determine test characteristics of FIT (OC-Sensor micro, Eiken, Japan) screening at different cut-off levels and compare these with guaiac-based faecal occult blood test (gFOBT) screening in an average risk population. A representative sample of the Dutch population (n=10 011), aged 50–74 years, was 1 : 1 randomised before invitation to gFOBT and FIT screening. Colonoscopy was offered to screenees with a positive gFOBT or FIT (cut-off 50 ng haemoglobin/ml). When varying the cut-off level between 50 and 200 ng ml⁻¹, the positivity rate of FIT ranged between 8.1% (95% CI: 7.2–9.1%) and 3.5% (95% CI: 2.9–4.2%), the detection rate of advanced neoplasia ranged between 3.2% (95% CI: 2.6–3.9%) and 2.1% (95% CI: 1.6–2.6%), and the specificity ranged between 95.5% (95% CI: 94.5–96.3%) and 98.8% (95% CI: 98.4–99.0%). At a cut-off value of 75 ng ml⁻¹, the detection rate was two times higher than with gFOBT screening (gFOBT: 1.2%; FIT: 2.5%; P<0.001), whereas the number needed to scope (NNscope) to find one screenee with advanced neoplasia was similar (2.2 vs 1.9; P=0.69). Immunochemical faecal occult blood testing is considerably more effective than gFOBT screening within the range of tested cut-off values. From our experience, a cut-off value of 75 ng ml⁻¹ provided an adequate positivity rate and an acceptable trade-off between detection rate and NNscope.

Cost evaluation in a colorectal cancer screening programme by faecal occult blood test in the District of Florence

OBJECTIVES

To evaluate the direct costs of first and repeat colorectal cancer screening by immunochemical faecal occult blood testing (I-FOBT).

METHODS

Florence district residents aged 50-70 were invited to undergo one-time I-FOBT every two years. Full colonoscopy was recommended for FOBT-positive subjects. Direct cost analysis was carried out separately for the first and repeat screening. All relevant resources consumed by the programme were calculated.

RESULTS

Among 25,428 or 62,369 subjects invited to the first or repeat screening, respectively, the corresponding participation rate was 47.8% or 52.3%, and the positivity rate was 4.4% and 3.3%. Corresponding detection rates and positive predictive values for cancer and advanced adenoma were 11.3% or 8.9% and 32.4% or 32.8%, respectively. The assessment phase accounted for the major cost, as compared with recruitment and screening. All cost indicators were slightly higher in the first screening compared with repeat screening. Cost per cancer and advanced adenoma detected was similar in the first or repeat screening. A higher than observed participation rate would have substantially reduced screening cost.

CONCLUSION

Analysis of I-FOBT-organized population-based screening cost demonstrates lower cost at repeat compared with first screening and provides reference for decision-making in screening implementation.

Immunochemical faecal occult blood test: number of samples and positivity cutoff. What is the best strategy for colorectal cancer screening?

Immunochemical faecal occult blood tests have shown a greater sensitivity than guaiac test in colorectal cancer screening, but optimal number of samples and cutoff have still to be defined. The aim of this multicentric study was to evaluate the performance of immunochemical-based screening strategies according to different positivity thresholds (80, 100, 120 ng ml(-1)) and single vs double sampling (one, at least one, or both positive samples) using 1-day sample with cutoff at 100 ng ml(-1) as the reference strategy. A total of 20 596 subjects aged 50-69 years were enrolled from Italian population-based screening programmes. Positivity rate was 4.5% for reference strategy and 8.0 and 2.0% for the most sensitive and the most specific strategy, respectively. Cancer detection rate of reference strategy was 2.8 per thousand, and ranged between 2.1 and 3.4 per thousand in other strategies; reference strategy detected 15.6 per thousand advanced adenomas (range=10.0-22.5 per thousand). The number needed to scope to find a cancer or an advanced adenoma was lower than 2 (1.5-1.7) for the most specific strategies, whereas it was 2.4-2.7, according to different thresholds, for the most sensitive ones. Different strategies seem to have a greater impact on adenomas rather than on cancer detection rate. The study provides information when deciding screening protocols and to adapt them to local resources.

Colorectal cancer mortality in two areas of Tuscany with different screening exposures

Several randomized trials have demonstrated the efficacy of colorectal cancer screening by the fecal occult blood test in reducing colorectal cancer mortality, but an evaluation of population-based screening programs is still lacking. We compared the colorectal cancer mortality rates (both adjusted rates and 3-year moving average rates) during 1985-2006 for two geographic areas in the provinces of Florence and Prato in the Tuscany region of Italy that began active population-based screening for colorectal cancer at different times: the Empolese-Mugello district, in the early 1980s, and the rest of the Florence and Prato provinces, in early 2000. A log-linear Poisson model was used to estimate the annual percent change in mortality and to examine whether geographic area modified the effect of calendar year on it. The Empolese-Mugello district had a greater decrease in colorectal cancer mortality than the rest of the Florence and Prato provinces (estimated annual percent change in age-adjusted colorectal cancer mortality rate, 2.7% decrease per year [95% confidence interval {CI} = 1.7% to 3.7%] vs 1.3% decrease per year [95% CI = 0.8% to 1.7%], respectively). The interaction between calendar period and area was statistically significant (P < .001). Our results support the hypothesis that the implementation of colorectal cancer screening in the early 1980s in the Empolese-Mugello district, where approximately 17 500 people were tested each year with the fecal occult blood test, was associated with a larger reduction in colorectal cancer mortality than that observed in the rest of Florence and Prato provinces, where screening started 15-20 years later and where approximately 38 000 people were screened each year beginning in 2000.

Sensitivity and specificity of lung cancer screening using chest low-dose computed tomography

Lung cancer screening programmes using chest X-ray and sputum cytology are routinely performed in Japan; however, the efficacy is insufficient. Screening using low-dose computed tomography (CT) is a more effective approach and has the potential to detect the disease more accurately. A total of 7183 low-dose CT screening tests for 4689 participants and 36 085 chest X-ray screening tests for 13 381 participants were conducted between August 1998 and May 2002. Sensitivity and specificity of lung cancer screening were calculated by both the detection method and the incidence method by linkage of the screening database and the Cancer Registry database. The preclinical detectable phase was assumed to be 1 year. Sensitivity and specificity by the detection method were 88.9 and 92.6% for low-dose CT and 78.3 and 97.0% for chest X-ray, respectively. Sensitivity of low-dose CT by the incidence method was 79.5%, whereas that of chest X-ray was 86.5%. Lung cancer screening using low-dose CT resulted in higher sensitivity and lower specificity than traditional screening according to the detection method. However, sensitivity by the incidence method was not as high as this. These findings demonstrate the potential for overdiagnosis in CT screening-detected cases.

Screening for colorectal cancer

Although there are several methods available for colon cancer screening, none is optimal. This article reviews methods for screening, including fecal occult blood tests, flexible sigmoidoscopy, colonoscopy, CT colonography, capsule endoscopy, and double contrast barium enema. A simple, inexpensive, noninvasive, and relatively sensitive screening test is needed to identify people at risk for developing advanced adenomas or colorectal cancer who would benefit from colonoscopy. It is hoped that new markers will be identified that perform better. Until then we fortunately have a variety of screening strategies that do work.

Comparing attendance and detection rate of colonoscopy with sigmoidoscopy and FIT for colorectal cancer screening

BACKGROUND & AIMS

We conducted a study to estimate population coverage and detection rate (DR) achievable through different strategies of colorectal cancer (CRC) screening.

METHODS

A population-based multicenter randomized trial comparing 3 strategies was used: (1) biennial immunologic fecal occult blood test (FIT), (2) "once only" sigmoidoscopy (FS), and (3) "once only" colonoscopy (TC). A random sample of men and women, aged 55 to 64 years, was drawn from general practitioners' (GP) rosters. Eligible subjects, randomized within GP, were mailed a personal invitation. Nonresponders in groups 2 and 3 were invited again at 12 and 24 months. Screenees with "high-risk" distal polyps (villous component >20%, high-grade dysplasia, CRC, size >or=10 mm, >2 adenomas) at FS, or with positive FIT, were referred for TC.

RESULTS

The attendance rate was 32.3% (1965/6075) for FIT, 32.3% (1944/6018) for FS, 26.5% (1597/6021) for TC. FIT detected 2 patients with CRC (0.1%) and 21 with an advanced adenoma (1.1%). The corresponding figures were as follows: 12 (0.6%) and 86 (4.5%) patients, respectively, for FS; 13 (0.8%) and 100 (6.3%) patients, respectively, for TC. To detect 1 advanced neoplasm, it would be necessary to invite 264 people with FIT, 60 with FS, 53 with TC. FS would have detected 27.3% of the proximal advanced neoplasms detected at TC. Assuming the same participation rate at TC as at FS, 48 TCs would be necessary to detect 1 additional advanced neoplasm missed by FS.

CONCLUSIONS

When participants are offered 1 screening test, participation is lower in a TC than in an FS program. However, DR of advanced neoplasia is higher with TC.

Sensitivity of latex agglutination faecal occult blood test in the Florence District population-based colorectal cancer screening programme

We evaluated the sensitivity for colorectal cancer (CRC) of the latex agglutination test (LAT), an immunochemical test routinely used in the Florence District screening programme since 2000. Sensitivity was calculated by the proportional interval cancer incidence method in a population of 27,503 consecutive subjects screened in 2000-2002, interval cancers being identified by linkage to the Tuscany Cancer Registry files. Sensitivity was calculated overall and by gender, age, time since last negative LAT, CRC site, and rank of screening. Overall 1- and 2-year sensitivity estimates were 80.7 and 71.5%, respectively, suggesting that faecal occult blood testing screening sensitivity may be suboptimal due to testing or programme quality problems. Increasing screening sensitivity might be achieved if the detection rate of advanced adenomas could be increased without unacceptable loss in specificity.

Early detection of cancer: ideas for a debate

Even if the overall number of cancer is increasing, the mortality has started to decrease in the Western World. The role of early detection in this decrease is a matter of debate. To assess its impact on mortality it is important to distinguish between diagnosis of cancer in symptomatic patients, and early detection in asymptomatic individuals who may self-refer or who may be offered ad hoc or systematic screening. The policies for early detection and screening vary greatly between European countries, despite many similarities in their cancer burden, and this partly reflects the uncertainties surrounding asymptomatic testing for cancer. A Task Force of European expert, held in Azzate (VA), Italy, established to address these issues, acknowledged the need for more research in the field of individual risk assessment since general statistics are more and more perceived as inadequate to design personal early detection plans. The group also recognised that combinations of early detection and screening will enforce the effectiveness of new treatments in curbing mortality curves, although policies will vary with different cancers.

Prospective multicenter evaluation of fecal tumor pyruvate kinase type M2 (M2-PK) as a screening biomarker for colorectal neoplasia

Proliferating cells, particularly the tumor cells, express a dimeric isoenzyme of pyruvate kinase, termed M2-PK. It's a direct target of several oncoproteins; the determination of fecal tumor pyruvate kinase type M2 (M2-PK) might be another promising tool for colorectal cancer (CRC) screening. In this study, we have evaluated fecal M2-PK as a screening biomarker for colorectal neoplasia. It was compared against fecal occult blood (FOB) and colonoscopy. Three hundred and seventeen consecutive subjects from 4 different centers were included. Stool specimens were collected before purgation, processed appropriately and were tested for FOB and quantitatively analyzed for M2-PK. Colonoscopies were performed by experienced endoscopists who were unaware of fecal assay results. At cutoff value of 4 U/ml, fecal M2-PK assay had a sensitivity, specificity, PPV and NPV of 81.1, 86.7, 71.1 and 61.9% respectively for diagnosing CRC whereas FOBT showed a sensitivity of 36.5%, specificity of 92.2%, PPV of 72.9% and NPV of 71.5% for CRC. Such low specificity of fecal M2-PK will lead to unacceptably high number of false positives if it is used for mass CRC screening, leading to unindicated colonoscopies with its associated inconveniences, risks and costs. CRC screening test must have high specificity; a high sensitivity is not as vital. To conclude, M2-PK was found to be a poor screening biomarker for CR neoplasia in a subject population at above average risk based on its prospective comparison with colonoscopy. These marginal performance characteristics do not permit its use as a screening tool for CR neoplasia in present clinical settings.

Evaluation of an immunochemical fecal occult blood test with automated reading in screening for colorectal cancer in a general average-risk population

Colorectal cancer screening is a high public health priority in all industrialized countries. However, the low sensitivity of the common guaiac screening test (HemoccultII) makes practitioners and public health decision makers reluctant to set up a national screening program. In recent years, immunochemical tests based on the use of a specific antibody have been found to be more sensitive than the HemoccultII test. However, for screening purposes, any gain in sensitivity is of interest only if specificity and positive predictive value are satisfactory. Our aim was to assess the performance of an immunochemical test with an automated reading technique (Magstream 1000) for different hemoglobin content cut-off points. The study was carried out in the general population aged 50-74 years in the geographic area of Cotentin (Normandy, France). From 1 January 2001 to 31 December 2002, 7,421 one-time screening tests (Magstream) were administered by general practitioners and occupational physicians to patients at the end of regular consultations. Colonoscopy was proposed to the 434 people with a positive test. All cancers occurring in the study population between 1 January 2001 and 31 December 2003 were collected by general practitioners, gastroenterologists and the local registry. At the usual positivity threshold (20 ng hemoglobin/ml), screening sensitivity and specificity at 2 years of follow-up with 95% CIs were, respectively, 0.85 (0.72-0.98) and 0.94 (0.94-0.95). If the hemoglobin content cut-off point had been set at 50 ng/ml instead of the usual cut-off, positivity would have been 3.1% and positive predictive value for a cancer or a large adenoma would have been 0.49, with sensitivity of 0.68-0.83 and specificity of 0.97. Our results suggest that use of an immunochemical test with an automated reading technique could improve the prospects for mass-screening for colorectal cancer since it offers a promising alternative to guaiac tests.

Randomized Trial of Different Screening Strategies for Colorectal Cancer: Patient Response and Detection Rates

BACKGROUND

Although there is general consensus concerning the efficacy of colorectal cancer screening, there is a lack of agreement about which routine screening strategy should be adopted. We compared the participation and detection rates achievable through different strategies of colorectal cancer screening.

METHODS

From November 1999 through June 2001 we conducted a multicenter, randomized trial in Italy among a sample of 55-64 year olds in the general population who had an average risk of colorectal cancer. People with previous colorectal cancer, adenomas, inflammatory bowel disease, a recent (< or =2 years) colorectal endoscopy or fecal occult blood test (FOBT), or two first-degree relatives with colorectal cancer were excluded. Eligible subjects were randomly assigned, within the roster of their general practitioner, to 1) biennial FOBT (delivered by mail), 2) biennial FOBT (delivered by general practitioner or a screening facility), 3) patient's choice of FOBT or "once-only" sigmoidoscopy, 4) "once-only" sigmoidoscopy, or 5) sigmoidoscopy followed by biennial FOBT. An immunologic FOBT was used. Participation and detection rates of the strategies tested were compared using multivariable logistic regression models that adjusted for age, sex, and screening center. All statistical tests were two-sided.

RESULTS

Of 28 319 people sampled, 1637 were excluded and 26 682 were randomly assigned to a screening arm. After excluding undelivered letters (n = 427), the participation rates for groups 1, 2, 3, 4, and 5 were 30.1% (682/2266), 28.1% (1654/5893), 27.1% (970/3579), 28.1% (1026/3650), and 28.1% (3049/10 867), respectively. Of the 2858 subjects screened by FOBT, 122 (4.3%) had a positive test result, 10 (3.5 per 1000) had colorectal cancer, and 39 (1.4%) had an advanced adenoma. Among the 4466 subjects screened by sigmoidoscopy, 341 (7.6%) were referred for colonoscopy, 18 (4 per 1000) had colorectal cancer, and 229 (5.1%) harbored an advanced adenoma.

CONCLUSIONS

The participation rates were similar for sigmoidoscopy and FOBT. The detection rate for advanced neoplasia was three times higher following screening by sigmoidoscopy than by FOBT.

Screening of patients at average risk for colon cancer

Both the incidence and the mortality from colorectal cancer can be substantially reduced by primary and secondary prevention. There are many screening tests for colorectal cancer, and any test should result in a reduction in colorectal cancer incidence and mortality. If the age-eligible population undergoes these screening tests, the burden of colorectal cancer should be substantially reduced. The scientific evidence related to secondary prevention, specifically screening of individuals at average risk for colorectal cancer, is presently reviewed.

Molecular stool screening for colorectal cancer

BACKGROUND

Mass screening for colorectal cancer reduces mortality and, with recent advances in molecular genetics, molecular stool-based tests have produced promising results. This article reviews this innovation and discusses its clinical significance.

METHODS

Medline searches were used to identify recent key articles relating to stool-based testing. Further articles were obtained by manual scanning of the reference lists of identified papers.

RESULTS

Current screening methods are based on endoscopic, radiological and stool-based testing. Recent recognition of the adenoma-carcinoma sequence and pathophysiological studies of colonic epithelium have enabled tumour markers to be used in the screening setting. Non-invasive molecular stool testing has now been shown to have a high sensitivity and specificity.

CONCLUSION

Recent studies on molecular stool-based testing have shown higher sensitivity and specificity than earlier studies, but larger clinical trials are required. Laboratory methods are still undergoing research, with the aim of improving sensitivity to allow large-scale testing.

Feasibility study of colorectal cancer screening by immunochemical faecal occult blood testing: results in a northern Italian community

AIM

Screening by means of faecal occult blood testing (FOBT) has proved to be effective in reducing colorectal cancer incidence and mortality. We performed a pilot screening for colorectal cancer by latex immunological FOBT in two municipalities of the region Valle d'Aosta, Italy, focusing on problems and obtaining indications for the feasibility and extension of the screening programme on a regional basis.

METHODS

A total of 2961 subjects aged 50-74 years were invited by mail to perform a one-day immunochemical FOBT without any dietary restrictions and with a positive threshold put at 100 ng/ml. Patients with positive tests were then invited to undergo colonoscopy and double-contrast barium enema if colonoscopy was incomplete.

RESULTS

A total of 1631 subjects performed the screening test with an overall compliance of 55.1%. Seventy-two subjects had a positive FOBT. Detection rates for cancer and adenomas were 1.8 per thousand and 16.6 per thousand, respectively. Positive predictive values (PPVs) for cancer and adenomas were 4.5% and 40.3%, respectively.

CONCLUSIONS

Screening had an adequate attendance rate and the majority of the indicators were satisfactory. The use of a one-day quantitative latex FOBT with no dietary restrictions, automation of the analytical procedure, and a positive threshold of 100 ng/ml has shown that a programme based on this test is feasible in both organizational and attendance terms. On the basis of this experience, the extension of the screening on a regional basis is suggested.

Prevention of advanced colorectal cancer by screening using the immunochemical faecal occult blood test: a case-control study

To evaluate colorectal cancer screening with faecal occult blood testing (FOBT) in terms of prevention of advanced cancers, we conducted a case-control study in the areas where an annual screening programme with immunochemical FOBT has been offered to all inhabitants aged 40 years or over. Cases were 357 consecutive patients in the study areas clinically diagnosed as having advanced colorectal cancer or a tumour invading the muscularis propriae or deeper, that is, T(2)-T(4) in TNM classification. Three controls were selected for each case matched by gender, age, residential area and exposure status to screening within 1 year before case diagnosis. The odds ratios (ORs) of developing advanced cancer were calculated using conditional logistic regression analyses. The OR for those screened within 3 years before the diagnosis vs those not screened was 0.54 (95% confidence interval (CI) 0.29-0.99). The ORs were lower for rectum than for colon (0.32-0.73 and 0.84-1.18 for rectum and colon, respectively). For those screened within the past 3 years, OR of developing advanced cancer in the rectum was 0.32 ( 95%CI: 0.12-0.84). A screening programme with immunochemical FOBT can be effective for prevention of advanced colorectal cancer. Risk reduction appears to be larger for rectal than for colon cancer. British Journal of Cancer (2003) 89, 23-28. doi:10.1038/sj.bjc.6601002 www.bjcancer.com

Fecal occult blood screening for colorectal cancer: open issues

Data from seven case-control and--mainly--three randomized clinical trials consistently indicate that biennial fecal occult blood screening (FOBT) can reduce colorectal cancer (CRC) mortality by approximately 20% after 10-18 years. The reduction may be greater in compliant subjects. In the long-term, incidence also appears to be reduced. There are suggestions that the effect of annual screening may be greater, although data are inadequate to quantify the potential advantages of annual versus biennial screening. The issue of the effectiveness of FOBT in the general population and, more important, of comparative cost-effectiveness with other possible screening tests for CRC, however, remain open to discussion.