A cost-effective analysis of the optimum number of stool specimens collected for immunochemical occult blood screening for colorectal cancer

Economic Evaluations Informed Exclusively by Real World Data: A Systematic Review

Economic evaluations using Real World Data (RWD) has been increasing in the very recent years, however, this source of information has several advantages and limitations. The aim of this review was to assess the quality of full economic evaluations (EE) developed using RWD. A systematic review was carried out through articles from the following databases: PubMed, Embase, Web of Science and Centre for Reviews and Dissemination. Included were studies that employed RWD for both costs and effectiveness. Methodological quality of the studies was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Of the 14,011 studies identified, 93 were included. Roughly half of the studies were carried out in a hospital setting. The most frequently assessed illnesses were neoplasms while the most evaluated interventions were pharmacological. The main source of costs and effects of RWD were information systems. The most frequent clinical outcome was survival. Some 47% of studies met at least 80% of CHEERS criteria. Studies were conducted with samples of 100-1000 patients or more, were randomized, and those that reported bias controls were those that fulfilled most CHEERS criteria. In conclusion, fewer than half the studies met 80% of the CHEERS checklist criteria.

Is a fecal occult blood test a useful tool for judging whether to perform capsule endoscopy in low-dose aspirin users with negative colonoscopy and esophagogastroduodenoscopy?

BACKGROUND

Aspirin use is reportedly not to be associated with fecal immunochemical occult blood test (FIT) false-positive results for the detection of colorectal cancer. The need for additional small bowel exploration in FIT-positive, low-dose aspirin users with a negative colonoscopy is controversial. The aim of this study was to assess the ability of FIT to judge whether capsule endoscopy (CE) should be performed in low-dose aspirin users with negative colonoscopy and esophagogastroduodenoscopy findings by comparing FIT results with CE findings.

METHODS

A total of 264 consecutive low-dose aspirin users with negative colonoscopy and esophagogastroduodenoscopy who were scheduled to undergo CE at five hospitals in Japan were enrolled. Patients had been offered FIT prior to the CE. The association between the FIT results and the CE findings was then assessed.

RESULTS

One hundred and fifty-seven patients were included in the final analysis. Eighty-four patients (53.5 %) had positive FIT results. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of positive FIT results for small bowel ulcers were 0.56, 0.47, 0.30, and 0.73, respectively. Furthermore, the NPV of positive FIT results for severe small bowel injury (Lewis score ≥790) was markedly high (0.90). When the analysis was performed only in low-dose aspirin users with anemia, the sensitivity of the positive FIT results was notably improved (0.72).

CONCLUSIONS

Small bowel evaluation using CE is not recommended for FIT-negative, low-dose aspirin users. However, small bowel evaluation using CE should be considered in both FIT-positive and anemic low-dose aspirin users.

Characteristics of colorectal tumours in asymptomatic patients with negative immunochemical faecal occult blood test results

The immunochemical faecal occult blood test (iFOBT) is a simple, non-invasive colorectal cancer (CRC) screening method for reducing CRC-related mortality. However, the sensitivity of iFOBT is imperfect and certain colonic neoplasms that require removal may be missed. The aim of this study was to investigate the incidence and characteristics of CRC in asymptomatic, iFOBT-negative patients who underwent opportunistic screening. A total of 919 subclinical patients (276 iFOBT-positive and 643 iFOBT-negative) in the health screening program of our hospital underwent total colonoscopy (TCS) within 2 years after iFOBT. The patients were divided into an iFOBT-positive and an iFOBT-negative group and the TCS findings were compared between the two groups. Although the incidence of advanced neoplasia (CRC, high-grade dysplasia, adenoma sized ≥10 mm and tubulovillous adenoma) was significantly higher in the iFOBT-positive group, these lesions were also found in 6.3% of iFOBT-negative patients. The lesions tended to be proximally located and non-protruding. In conclusion, screening with iFOBT remains clinically significant. However, colonoscopy is indispensable for reducing the incidence and mortality of CRC.

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.

Fecal immunochemical test accuracy in familial risk colorectal cancer screening

There is little information on fecal immunochemical test (FIT) in familial risk colorectal cancer (CRC) screening. Our study assesses FIT accuracy, number needed to scope (NNS) and cost to detect a CRC and an advanced neoplasia (AN) in this setting. We performed a multicentric, prospective, double-blind study of diagnostic tests on individuals with first-degree relatives (FDRs) with CRC submitted to screening colonoscopy. Two stool samples were collected and fecal hemoglobin in the first sample (FIT1) and the highest in both samples (FITmax) were determined. Areas under the curve (AUC) for CRC and AN as well as the best FIT1 and FITmax cutoff value for CRC were determined. At this threshold, NNS and the cost per lesion detected were calculated. A total of 595 individuals were included (one FDR > 60 years, 413; two FDR or one ≤ 60 years, 182). AN and CRC were found in 64 (10.8%) and six (1%) patients, respectively. For CRC diagnosis, FIT1 AUC was 0.96 [95% confidence interval (CI): 0.95-0.98] and FITmax AUC was 0.95 (95% CI: 0.93-0.97). For AN diagnosis, FIT1 and FITmax AUC were 0.74 (95% CI: 0.66-0.82). The best cutoff point for CRC was 115. At this threshold, the NNS to detect a CRC was 5.67 and 7.67, and the cost per CRC was 1,064€ and 1591.33€ on FIT1 and FITmax strategies, respectively. FIT shows high accuracy to detect CRC in familial CRC screening. Performing two tests does not improve diagnostic accuracy, but increases cost and NNS to detect a lesion.

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.

Evaluation of mucosal healing of ulcerative colitis by a quantitative fecal immunochemical test

OBJECTIVES

Accumulating evidence has underlined the importance of mucosal healing as a treatment goal for ulcerative colitis (UC). Quantitative fecal immunochemical tests (FITs), which can rapidly quantify fecal blood with automated equipment, have been used recently to screen for colorectal neoplasia. The aim of this study is to determine whether an FIT can evaluate mucosal healing in UC.

METHODS

Feces collected from UC patients who underwent colonoscopy were examined by FITs, and results were compared with colonoscopic findings. Mucosal status was assessed using the Mayo endoscopic subscore classification. Maximum score for the colorectum in each patient was recorded.

RESULTS

Evaluated were FIT results in conjunction with 310 colonoscopies that were performed in 152 UC patients. A large majority of patients with a Mayo 0 endoscopic score had negative FIT (<100 ng/ml) results (92%), and the proportion of negative FIT results decreased with increases in the Mayo score (Mayo 1: 47%, Mayo 2: 13%, Mayo 3: 12%, P<0.0001, Cochran-Armitage trend test). When the negative FIT was defined as <100 ng/ml, the sensitivity and specificity of a negative FIT for mucosal healing (Mayo 0) were 0.92 and 0.71, respectively. When mucosal healing was defined as Mayo 0 or 1, those were 0.60 and 0.87, respectively. In addition, a positive FIT (≥100 ng/ml) predicted mucosal inflammation (Mayo 2 or 3) with sensitivity 0.87 and specificity 0.60, respectively.

CONCLUSIONS

The FIT can effectively and noninvasively evaluate mucosal healing in UC. This easy, rapid method can help evaluate and control disease activity of UC.

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.

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

OBJECTIVES

Although some studies have shown that the quantitative, immunochemical fecal occult blood test (FOBT) (qFIT) has better performance characteristics than the standard guaiac-based FOBT (GT) for identifying advanced colorectal neoplasia (ACRN), there is limited information on test performance of these tests in average-risk populations.

METHODS

Seven hundred seventy consecutive average-risk patients from four centers who were undergoing screening colonoscopy also provided stool samples. Stool specimens from three consecutive bowel movements were applied to a hemoccult II test card (Beckman Coulter, Fullerton, CA) and OC-SENSA MICRO (Eiken Chemical, Tokyo, Japan) sampling probes at the same time. We measured the diagnostic value of the qFIT for detecting an ACRN by using three criteria: sensitivity, specificity, and likelihood ratios. A receiver operating characteristic curve for determining the qFIT cutoff values and the number of tests that best discriminated between ACRNs and other findings were determined.

RESULTS

Seventy-eight ACRNs were identified during colonoscopy. At all hemoglobin thresholds, the sensitivity of the qFIT was higher than that of the GT for cancer or ACRN. The sensitivity and specificity of the GT for detecting advanced adenomas, cancer, and ACRNs were 13.6%/92.4%, 30.8%/92.4%, and 16.7%/92.9%, respectively. Using the 100 ng/ml cut point and three-sample qFIT results, the sensitivity and specificity of the qFIT for detecting advanced adenomas, cancer, and ACRNs were 33.9%/90.6%, 84.6%/89.8%, and 43.7%/91.9%, respectively. The area under the curve for cancer indicated that using either 2 or 3 tests provided the best discrimination for cancer.

CONCLUSIONS

The qFIT provides a higher sensitivity for detecting ACRN and cancer than the GT, and has an acceptable specificity that significantly reduces the need for colonoscopic evaluation in the screened population.

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.

Cumulative evaluation of a quantitative immunochemical fecal occult blood test to determine its optimal clinical use

BACKGROUND

Quantified, human hemoglobin (Hb)-specific, immunochemical fecal occult blood test (IFOBT) measurements are now used for colorectal cancer (CRC) screening. The objective was to evaluate sensitivity and specificity for CRC and advanced adenomatous polyps (APs) by the fecal Hb threshold used to determine a positive test and the number of IFOBTs prepared per test, so as to determine the least number of colonoscopies required to detect a neoplasm.

METHODS

Cumulative data were analyzed from a prospective cross-sectional double-blind study of 1682 consecutive, ambulatory, nonbleeding colonoscopy patients who volunteered for IFOBTs, most of above average risk, from 3 ambulatory-endoscopy centers. Fecal Hb was measured in 3 samples and analyzed by an automated instrument, and the highest result >or=50 ng Hb/mL of buffer was related to findings.

RESULTS

Colonoscopy identified CRC in 20 patients and advanced APs in 129. Sensitivity for either was best when any of 3 tests had >or=50 ng Hb/mL of buffer; sensitivity was 61.1% (95% confidence interval [CI], 53.2-68.9), and specificity was 87.8% (95% CI, 86.2-89.4). Positive tests identified 100% of CRCs and 55% of advanced APs every 3.1 colonoscopies. Sensitivity of a single test at the commonly used 100-ng Hb/mL threshold was lower at 31.5% (95% CI, 24.1-39.0) (P<.001), but specificity was higher at 96.4% (95% CI, 95.5-97.3) (P<.001). Positive tests identified 65% of CRCs and 26.4% of advanced APs every 2.2 colonoscopies.

CONCLUSIONS

The fecal Hb cutoff chosen by the screener and the number of samples collected per patient determine sensitivity and specificity for CRC/advanced AP; these factors determine the number of colonoscopies needed for positive tests and neoplasia yield. This information provides guidelines for IFOBT screening. Limitations are 1-time screening and most examinees not being at average risk for CRC.

Prediction of flare-ups of ulcerative colitis using quantitative immunochemical fecal occult blood test

AIM: To examine the feasibility of predicting the flare-up of ulcerative colitis (UC) before symptoms emerge using the immunochemical fecal occult blood test (I-FOBT).

METHODS: We prospectively measured fecal hemoglobin concentrations in 78 UC patients using the I-FOBT every 1 or 2 mo.

RESULTS: During a 20 mo-period, 823 fecal samples from 78 patients were submitted. The median concentration of fecal hemoglobin was 41 ng/mL (range: 0-392 500 ng/mL). There were three types of patients with regard to the correlation between I-FOBT and patient symptoms; the synchronous transition type with symptoms (44 patients), the unrelated type with symptoms (19 patients), and the flare-up predictive type (15 patients). In patients with the flare-up predictive type, the values of I-FOBT were generally low during the study period with stable symptoms. Two to four weeks before the flare-up of symptoms, the I-FOBT values were high. Thus, in these patients, I-FOBT could predict the flare-up before symptoms emerged.

CONCLUSION: Flare-up could be predicted by I-FOBT in approximately 20% of UC patients. These results warrant periodical I-FOBT in UC patients.

Identification of colorectal adenomas by a quantitative immunochemical faecal occult blood screening test depends on adenoma characteristics, development threshold used and number of tests performed

BACKGROUND

Faecal occult blood tests (FOBT) are faulted by low sensitivity for advanced adenomatous polyps (AAP). Quantified, immunochemical, haemoglobin (Hb)-specific immunochemical FOBT (I-FOBT) measurements are now used for colorectal screening.

AIMS

To correlate adenoma characteristics to amount of faecal Hb lost and to evaluate sensitivity and specificity for AAP by faecal Hb development threshold used and number of I-FOBTs collected.

METHODS

Three daily I-FOBTs were collected and analysed in 1221 patients scheduled for colonoscopy. Faecal Hb was analysed as ngHb/mL of buffer and the highest result related to colonoscopy findings.

RESULTS

In 1204 patients without cancer, colonoscopy identified adenomas in 294, 99 with AAPs. Adenoma patients had elevated faecal Hb increasing with advanced histology, size, pedunculated shape and multiplicity (P < 0.001 for all). At 50 ngHb/mL threshold, sensitivity and specificity for AAPs were 54.5% (95%CI 44.7, 64.7) and 88.1% (95%CI 86.2, 90.1) for three tests. At higher thresholds, sensitivity decreased, but was significantly higher with more samples collected. Conversely, specificity increased at higher thresholds, but decreased with more samples.

CONCLUSIONS

Faecal Hb loss from adenomas is significantly associated with size, number and advanced features. Sensitivity and specificity for AAPs are determined by test threshold chosen and number of samples collected; these determine the number of colonoscopies needed for positive tests.

Quantitative colonoscopic evaluation of relative efficiencies of an immunochemical faecal occult blood test and a sensitive guaiac test for detecting significant colorectal neoplasms

BACKGROUND

The guaiac faecal occult blood test (G-FOBT), HemoccultSENSA, is sensitive for significant neoplasms [colorectal cancer (CRC), advanced adenomatous polyps (AAP)], but faulted by non-specificity for human haemoglobin (Hb). Quantified, Hb- specific, immunochemical faecal occult blood tests (I-FOBT) are now used.

AIMS

To (i) compare I-FOBT and G-FOBT efficacy in identifying significant neoplasms and colonoscopy needs for positive tests and (ii) examine number of I-FOBTs needed and test threshold to use for equivalent or better sensitivity than G-FOBT and fewest colonoscopies for positive tests.

METHODS

Three daily G-FOBTs and I-FOBTs were collected and analysed in 330 patients scheduled for colonoscopy.

RESULTS

Colonoscopy found significant neoplasms in 32 patients, 6 CRC, 26 AAP. G-FOBT, sensitivity and specificity were 53.1% (17 neoplasms) and 59.4%, resulting in 8.1 colonoscopies/neoplasm. One I-FOBT having >or=50 ngHb/mL of buffer provided equivalent sensitivity but 94.0% specificity, resulting in 2.1 colonoscopies/neoplasm. By analysing the higher of two I-FOBTs at 50 ngHb/mL threshold, sensitivity increased to 68.8% (22 neoplasms, P = 0.063), specificity fell to 91.9% (P < 0.001), but still required 2.1 colonoscopies/neoplasm.

CONCLUSIONS

In this population, quantified I-FOBT had significantly better specificity than G-FOBT for significant neoplasms, reducing the number of colonoscopies needed/neoplasm detected. Results depend on the number of I-FOBTs performed and the chosen development threshold.

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.

UroVysion FISH test for detecting urothelial cancers: meta-analysis of diagnostic accuracy and comparison with urinary cytology testing

OBJECTIVES

Since the introduction of the UroVysion test for detecting urothelial cancers in urine, its reported performance has varied. This article systematically analyzed reported results.

METHODS

Articles in English conforming to the Oxford EBM criteria were included, with the evaluation focused on cancers that were histologically confirmed at the time of testing rather than on any cancers that might develop later. Where applicable, samples with no cells were reclassified as negative so as to further improve the actual estimation of test performance. Where available, cytology data were also analyzed. Meta-DiSc software was used for the statistical analyses.

RESULTS

We identified 14 studies involving 2477 FISH tests. The overall prevalence of urothelial cancers was 35%. The pooled sensitivity and specificity of all studies were 72% (69%-75%) and 83% (82%-85%), respectively. Cytology data were available from 12 studies, with the overall sensitivity and specificity being 42% (38%-45%) and 96% (95%-97%). Excluding Ta tumors, the sensitivity was 86% (82%-89%) for UroVysion and 61% (56%-66%) for cytology. The overall performance was higher for UroVysion than for cytology: diagnostic odds ratio, 16.8 and 14.1; AUC, 0.867 (SE 0.021) and 0.626 (SE 0.091). These differences in overall test performance measures almost disappeared when superficial cancer cases were excluded from the analysis.

CONCLUSIONS

The published trials suggest that for a general mix of cases, cytology results are highly specific. However, a negative cytology result does not meaningfully change the post-test probability of the presence of urothelial cancer. UroVysion FISH test results should not be considered to provide conclusive evidence for the presence or absence of urothelial cancer, but both positive and negative results do moderately influence the post-test probability of disease.

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.

Screening for colorectal cancer in average-risk populations

Screening average-risk populations for colorectal cancer can reduce the incidence and mortality of colorectal cancer. Effectiveness depends on programmatic adherence and quality. This review discusses the evidence supporting the use of currently available screening tests. The discussion specifically focuses on programmatic issues and highlights the importance of quality assurance in each program.

Performance characteristics and evaluation of an automated-developed and quantitative, immunochemical, fecal occult blood screening test

OBJECTIVES

Guaiac fecal occult blood colorectal cancer (CRC) screening tests (FOBT) are faulted for low sensitivity and nonspecificity for human hemoglobin (Hb). Automated-developed, immunochemical, human Hb FOBT (I-FOBT) is specific, eliminates diet restrictions, and Hb quantification allows selection of a threshold for colonoscopy. Aims were to determine 1) test reproducibility; 2) test stability; 3) intrapatient daily I-FOBT variation; 4) test sensitivity and specificity for neoplasia in 500 symptomatic/high-risk patients undergoing colonoscopy; and 5) to correlate fecal Hb measurements with findings.

METHODS

The desktop instrument OC-Sensor (Eiken, Japan) automatically develops and quantitates 50 tests/h for Hb. Patients prepared three tests, which were quantified and then 1) repeatedly re-examined; 2) stored at 4 degrees C or 20 degrees C or 28 degrees C and repeatedly examined; and 3) fecal Hb levels were correlated with colonoscopic findings.

RESULTS

Five I-FOBTs re-examined five times in 1 day had no significant measurement changes. Thirty tests stored for 21 or more days had a decay/day of 0.3%+/- 0.4 at 4 degrees C (NS), 2.2%+/- 1.7 at 20 degrees C (NS), and 3.7%+/- 1.8 at 28 degrees C (p < 0.05). There were intrapatient variations between the three daily I-FOBTs (NS). At the recommended 100 ng Hb/mL threshold, all six cases of CRCs and 20 out of 28 cases of advanced adenomas were detected; evaluated together their sensitivity and specificity were 76.5% and 95.3%.

CONCLUSIONS

Desktop, automated-developed, quantitative I-FOBT is now available. Refrigerated OC-Sensor samples are stable for 21 days, easy to prepare and develop and, at the 100 ng Hb/mL threshold, have high sensitivity, specificity, and negative predictive values for significant neoplasia. Suitability for population CRC screening awaits further evaluation.

A comparison of the immunochemical fecal occult blood test and total colonoscopy in the asymptomatic population

BACKGROUND & AIMS

The fecal occult blood test (FOBT) is recommended as a screening test for colorectal cancer, but there are few reliable studies on the accuracy of immunochemical FOBT. The aim of this study was to analyze the sensitivity of immunochemical FOBT and to compare the results with the findings from complete colonoscopy.

METHODS

Asymptomatic adults underwent 1-time immunochemical FOBT and total colonoscopy simultaneously. The prevalence and location of colorectal neoplasia were determined by colonoscopy. The results of immunochemical FOBT and the colonoscopic findings were compared.

RESULTS

Of 21,805 patients, immunochemical FOBT was positive in 1231 cases (5.6%). The sensitivity of 1-time immunochemical FOBT for detecting advanced neoplasia and invasive cancer was 27.1% and 65.8%, respectively. In addition, the sensitivity for invasive cancer according to Dukes' stage showed 50.0% for Dukes' stage A, 70.0% for Dukes' stage B, and 78.3% for Dukes' stages C or D. The sensitivity for detecting advanced neoplasia at the proximal colon was significantly lower than that detected in the distal colon (16.3% vs 30.7%, P = .00007).

CONCLUSIONS

Although the screening of asymptomatic patients with immunochemical FOBT can identify patients with colorectal neoplasia to a certain extent, the sensitivity is relatively low and different according to the tumor location. Therefore, programmatic and repeated screening by immunochemical FOBT may be necessary to increase sensitivity for colorectal cancer detection.

Evaluation of the optimum cut-off point in immunochemical occult blood testing in screening for colorectal cancer

This study was carried out to assess, from the aspects of cost-effectiveness and diagnostic validity, the optimum cut-off point for immunochemical occult blood testing using a 2-day method as a means of screening for colorectal cancer. Four thousand, two hundred and sixty asymptomatic individuals were subjects of this study. They gave samples for an immunochemical fecal occult blood test, and colonoscopy was carried out during a medical check-up. For evaluation of the optimum cut-off point, three cut-off levels of fecal haemoglobin, 50, 150 and 300 ng/ml, were used. A total of 27 patients with colorectal cancer were diagnosed. The average costs to detect one patient with colorectal cancer and the sensitivity and specificity of these three cut-off points of fecal haemoglobin were evaluated. The average costs for the detection of one cancer case were calculated as $2870.45 for cut-off level of 50 ng/ml, $2492.98 for that of 150 ng/ml and $3329.09 for that of 300 ng/ml, respectively. The sensitivity and specificity were calculated as 89 and 94% for the 50 ng/ml cut-off level, 81% and 96% for the 150 ng/ml cut-off level and 56 and 97% for the 300 ng/ml cut-off level, respectively, indicating a significant difference in the sensitivity between the 50 and 300 ng/ml levels (P<0.05), as well as between the 150 and 300 ng/ml levels (P<0.05), and a significant difference in the specificity between the 50 and 300 ng/ml levels (P<0.05). However, no significant difference was observed in the specificity between the 50 and 150 ng/ml levels. The findings show that 150 ng/ml of fecal haemoglobin is the optimal cut-off point when carrying out the OC-Hemodia test as a means of screening for colorectal cancer.