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

Noninvasive Colorectal Cancer Prevention Options in Older Adults

Colorectal cancer (CRC) is a leading cause of morbidity and mortality worldwide and its incidence increases with age. The proportion of older adults in the United States continues to rise, making CRC prevention a key health priority for our aging population. CRC is a largely preventable disease through screening and polyp surveillance, and noninvasive modalities represent an important option for older adults in whom the burdens and risks of invasive testing are higher compared with younger adults. This review highlights the evidence, risks, and benefits of noninvasive CRC screening and surveillance options in older adults and discusses the challenges of CRC prevention in this cohort.

Potential Modifiers and Different Cut-offs in Diagnostic Accuracy of Fecal Immunochemical Test in Detecting Advanced Colon Neoplasia: A Diagnostic Test Accuracy Meta-analysis

Background: Fecal immunoglobulin test (FIT) has been advocated as the first line of screening for colorectal cancer (CRC) in several jurisdictions. Most studies have focused on CRC as the outcome of interest. Our goal was to quantify the diagnostic accuracy of different thresholds of FIT as compared with colonoscopy for detection of advanced colonic neoplasia and potential modifiers using proper Cochrane methodology. Methods: A comprehensive electronic search was performed for studies on FIT using colonoscopy as the reference standard to detect advanced neoplasia. Cochrane methodology was used to perform a diagnostic test accuracy (DTA) meta-analysis. Diagnostic accuracy of different cut-offs of FIT, including 25, 50, 75, 100, 150, and 200 ng/mL, were calculated separately. Meta-regression analysis was also performed to detect potential a priori modifiers, including age, location of the tumor, and time from FIT to colonoscopy. Results: Twenty-four studies were included with no evidence of publication bias. The sensitivity of FIT did not decrease with lowering the cut-off, although specificity increased in higher cut-offs. Commonly used cut-offs of 50 ng/mL, 75 ng/mL, and 100 ng/mL for FIT provided sensitivity of 39%, 36%, 27% and specificity of 92%, 94%, 96%, respectively. Diagnostic accuracy of FIT did not significantly differ in proximal versus distal lesions or in individuals below or over the age of 50 years. The results remained robust in a meta-regression of the location of the study, time from FIT to colonoscopy, and methodological quality. Conclusion: The sensitivity of FIT might have been overestimated in previous studies focusing on CRC, and it seems to be independent of age, location of neoplasia, or cut-offs, contrary to some previous studies. Lowering the cut-off will reduce the diagnostic odds ratio (DOR) by increasing specificity but without any effect on sensitivity.

Clinical implications and nomogram prediction of long noncoding RNA FRGCA as diagnostic and prognostic indicators in colon adenocarcinoma

Colorectal cancer, especially colon adenocarcinoma (COAD), is associated with significant morbidity and mortality worldwide. Long noncoding RNA (lncRNA) has been implicated in tumorigenesis. The aim of the present study was to elucidate the potential diagnostic and prognostic values of lncRNA FRGCA in COAD.The data of 438 COAD patients were retrieved for analysis. Diagnostic significance was evaluated using tumor and nontumor tissues. Prognostic significance was evaluated using a Cox proportional regression model. Stratified analysis was performed to identify associations between clinical factors and lncRNA FRGCA expression. A nomogram was constructed using the clinical factors and lncRNA FRGCA for survival prediction. Enrichment analysis identified gene ontologies and metabolic pathways of mRNAs with high Pearson correlation coefficients with lncRNA FRGCA.lncRNA FRGCA was highly expressed in tumor tissues of COAD and demonstrated diagnostic value (area under curve = 0.763, P < .0001). Prognostic significance analysis indicated that lncRNA FRGCA had prognostic value in COAD [adjusted P < .001, hazard ratio (HR) = 0.444, 95% confidence interval (95% CI) = 0.288-0.685] and high expression of lncRNA FRGCA indicated better survival in COAD. A nomogram was evaluated for prediction of survival at 1, 3, and 5 years. Enrichment analysis revealed many mRNAs involved in the structural constituents of the mitochondrial inner membrane and translational termination, protein binding, translation, ribosome, oxidative phosphorylation, and metabolic pathways, especially the nucleoplasm.Differentially expressed in tumor vs nontumor tissues, lncRNA FRGCA had both diagnostic and prognostic implications in COAD, which may be associated with ribosome metabolism, oxidative phosphorylation, and nucleoplasm-related metabolic pathways.

Benefits of switching from guaiac-based faecal occult blood to faecal immunochemical testing: experience from the Wallonia-Brussels colorectal cancer screening programme

Background

Faecal immunochemical tests (FITs) have replaced guaiac-based faecal occult blood test (gFOBTs) in several colorectal cancer (CRC) screening programmes. We aimed to evaluate the benefits of this transition based on the Wallonia–Brussels-organised CRC screening programme.

Methods

A total of 1,569,868 individuals aged 50–74 years, who were invited to screening during 2009–2017, were studied by linking their screening records with insurance, pathology and cancer data in the Belgian Cancer Registry. We compared neoplasm detection rates and positive predictive values (PPVs) of gFOBT and FIT at 15 µg haemoglobin per gram cut-off in screen-naive individuals. We furthermore examined the incidence rates of interval cancer in gFOBT- and FIT-based screening programme.

Results

Advanced neoplasms were detected less frequently by gFOBT (0.8%) than by FIT (1.3%), with a difference of 0.5% (P < 0.01). PPVs were lower for gFOBT (15.1%) than for FIT (21.7%) for advanced neoplasms (difference 6.6%, P < 0.01). Compared to participants with negative gFOBT, those with negative FIT were 77% less likely to develop interval cancer (incidence rate ratio 0.23, 95% confidence interval 0.16–0.33).

Conclusion

Our study demonstrated that in an organised CRC screening programme, replacing gFOBT with FIT improved neoplasm detection rate and substantially reduced interval cancer incidence.

Quality Metrics of a Fecal Immunochemical Test-Based Colorectal Cancer Screening Program in Korea

Background/Aims

Knowledge regarding the quality metrics of fecal immunochemical test (FIT)-based colorectal cancer screening programs is limited. The aim of this study was to investigate the performance and quality metrics of a FIT-based screening program.

Methods

In our screening program, asymptomatic subjects aged ≥50 years underwent an annual FIT, and subjects with positive FIT results underwent a subsequent colonoscopy. The performance of the FIT and colonoscopy was analyzed in individuals with a positive FIT who completed the program between 2009 and 2015 at a university hospital.

Results

Among the 51,439 screened participants, 75.1% completed the FIT. The positive rate was 1.1%, and the colonoscopy completion rate in these patients was 68.6%. The positive predictive values of cancer and advanced neoplasia were 5.5% and 19.1%, respectively. The adenoma detection rate in the patients who underwent colonoscopy after a positive FIT was 48.2% (60.0% for men and 33.6% for women). The group with the highest tertile quantitative FIT level showed a significantly higher detection rate of advanced neoplasia than the group with the lowest tertile (odds ratio, 2.6; 95% confidence interval, 1.4 to 5.1; p<0.001).

Conclusions

The quality metrics used in the United States and Europe may be directly introduced to other countries, including Korea. However, the optimal quality metrics should be established in each country.

Forensic luminol reaction for detecting fecal occult blood in experimental mice

Fecal occult blood (FOB) is a sign of gastrointestinal diseases, such as intestinal ulcers and colorectal cancer. In experimental animal studies, there is no standard method to detect FOB. Here, we present a simple protocol to detect FOB in mice, using the Luminol Reaction Experiment Kit^® that was originally designed to detect bloodstains at a crime scene in criminal forensics. To obtain positive control bloody feces, we used an indomethacin-induced intestinal ulcer model in mice. By mixing small pieces of feces with a luminol solution, the fecal solution emitted visible blue–white chemiluminescence in dark field when feces contained hemoglobin. We also established a method for semi-quantification of hemoglobin content in the fecal solution, using a luminometer. This method is simple, quick, economical and semi-quantitative, allowing researchers to detect FOB in experimental mice.

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

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

Risk Factors for False Fecal Immunochemical Test Results in Colorectal Cancer Screening

GOALS

We investigated the factors associated with false fecal immunochemical test (FIT) results for advanced colorectal neoplasm (ACRN).

BACKGROUND

Data on whether certain subgroups of patients have an increased risk of inaccurate FIT results are extremely limited.

STUDY

This was a retrospective study conducted in a university hospital in Korea from June 2013 to May 2015. Out of 34,547 participants who had an FIT completed, we analyzed a total of 3990 subjects aged 50 years and above who underwent colonoscopy.

RESULTS

The rates of false-negative and false-positive results were 58.0% and 15.7%, respectively. Elevated fasting blood glucose [adjusted odds ratio (AOR), 0.59; 95% confidence interval (CI), 0.36-0.97], the presence of high-grade dysplasia (AOR, 0.49; 95% CI, 0.25-0.95), 3 or more adenomas (AOR, 0.56; 95% CI, 0.35-0.89), cancer (AOR, 0.20; 95% CI, 0.11-0.38), and distal ACRN (AOR, 0.61; 95% CI, 0.39-0.96) were associated with a lower risk of false-negative FIT results. The presence of proximal ACRN (AOR, 1.59; 95% CI, 1.01-2.51) and adenoma ≥10 mm (AOR, 4.38; 95% CI, 2.17-8.87) were associated with a higher risk of false-negative results. Older age (70 y and above; AOR, 1.67; 95% CI, 1.29-2.17), diverticulum (AOR, 1.94; 95% CI, 1.45-2.58), and hemorrhoid (AOR, 1.63; 95% CI, 1.32-2.01) were associated with false-positive results.

CONCLUSIONS

Subjects with a higher risk of false-negative results should be prioritized for earlier colonoscopy and subjects with inaccurate results should be more cautiously considered for screening by using modalities other than FIT. Our findings will contribute to individualization of screening programs.

Diagnostic accuracy of faecal biomarkers in detecting colorectal cancer and adenoma in symptomatic patients

BACKGROUND

The diagnosis of colorectal cancer (CRC) can be difficult as symptoms are variable with poor specificity. Thus, there is a quest for simple, non-invasive testing that can help streamline those with significant colonic pathology.

AIM

To assess using faecal immunochemical test for haemoglobin (FIT) or faecal calprotectin (FCP) to detect CRC and adenoma in symptomatic patients referred from primary care.

METHODS

A total of 799 referred for urgent lower gastrointestinal investigations were prospectively recruited. Of these, 430 completed colonic investigations and returned stool samples, and were included in the final statistical analysis. Faecal immunochemical test for haemoglobin was performed on HM-JACKarc analyser (Kyowa Medex, Tokyo, Japan), and FCP by the EliA Calprotectin immunoassay (Thermo Fisher Scientific, Waltham, United States).

RESULTS

The negative predictive value (NPV) using FIT alone or both markers (FIT and FCP) in combination was similar at 99% for CRC, with a sensitivity and specificity of 84% and 93%, respectively. FIT measurements were significantly higher in left-sided colonic lesions compared with the right side; 713 vs. 94; P = 0.0203). For adenoma, the NPV using FIT alone, or both markers (FIT and FCP) in combination, was similar at 94% with a sensitivity and specificity of 69% and 56%, respectively.

CONCLUSIONS

Undetectable faecal immunochemical test for haemoglobin is sufficiently sensitive to exclude colorectal cancer, with higher values in left-sided lesions. FCP in combination does not appear to provide additional diagnostic information. Further studies to determine the health economic benefits of implementing faecal immunochemical test for haemoglobin in primary care are required.

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.

Participant uptake of the fecal immunochemical test decreases with the two-sample regimen compared with one-sample FIT

BACKGROUND

Fecal immunochemical tests (FITs) are recommended to screen average-risk adults for colorectal cancer (CRC). Little research has examined whether a two-sample FIT affects participant uptake, compared with a one-sample FIT. Examining participant uptake is important, as evidence suggests that a two-sample FIT may increase the sensitivity to detect CRC.

OBJECTIVE

This study had two objectives: (i) to evaluate FIT completion in a population that received either a one-sample FIT kit (1-FIT) or a two-sample FIT kit (2-FIT) and (ii) to understand whether uptake varies by age, sex, or receipt of prior CRC screening.

METHODS

We conducted a randomized controlled trial in which 3081 participants who were aged between 50 and 75 years and were at an average risk for CRC, and who had requested FITs, randomly received 1-FIT (n=1540) or 2-FIT (n=1541) kits. FIT completion was defined as the completion and return of a one-sample test by the patients in the 1-FIT group or of both sample tests by those in the 2-FIT group. Cox proportional hazard regression models were used to determine the independent effect of group type (2-FIT vs. 1-FIT) on the completion of the FIT, adjusting for age, sex, and receipt of prior CRC screening.

RESULTS

The 2-FIT group had lower test completion rates (hazard ratio=0.87; 95% confidence interval=0.78-0.97; P=0.01) after adjusting for age, sex, and receipt of prior CRC screening. Participant uptake did not vary by age, sex, or receipt of prior CRC screening.

CONCLUSION

This unique, rigorous randomized controlled trial found that the 2-FIT regimen decreases completion of FIT. Further research is needed to understand whether decreases in participant uptake are offset by increased gains in test sensitivity.

Diagnostic accuracy of fecal immunochemical test in average- and familial-risk colorectal cancer screening

BACKGROUND

There is little information about the fecal immunochemical test (FIT) in familial-risk colorectal cancer (CRC) screening.

OBJECTIVES

The objective of this article is to investigate whether FIT diagnostic accuracy for advanced neoplasia (AN) differs between average and familial-risk (first-degree relative) patients.

METHODS

A total of 1317 consecutive participants (595 familial) who collected one stool sample before performing a colonoscopy as a CRC screening test were included. FIT diagnostic accuracy for AN was evaluated with Chi-square test at a 20 µg hemoglobin/g of feces cut-off value. Finally, we determined which variables were independently related to AN.

RESULTS

An AN was found in 151 (11.5%) patients. The overall accuracy was not statistically different between both cohorts for AN (88.4%, 91.7%; p = 0.051). At the cut-off stablished, differences in FIT sensitivity (31.1%, 40.6%; p = 0.2) or specificity (96.5%, 97.3%; p = 0.1) were not statistically significant. Finally, independent variables such as sex (male) (odds ratio (OR) 2.1, 95% confidence interval (CI) 1.4-3.1), age (50-65, >65 years) (OR 2.1, 95% CI 1.1-4.3; OR 2.7, 95% CI 1.2-6.1), previous colonoscopy (OR 0.4, 95% CI 0.2-0.9) and FIT ≥20 µg/g feces (OR 17.7, 95% CI 10.8-29.1) were associated with AN diagnosis.

CONCLUSIONS

FIT accuracy for AN detection is equivalent in average and familial-risk CRC screening cohorts.

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.

Sex is a stronger predictor of colorectal adenoma and advanced adenoma than fecal occult blood test

Due to high costs and limited availability of screening colonoscopy, some screening programs require a positive fecal occult blood test (FOBT) before screening colonoscopy is remunerated. As male sex is a strong predictor of adenoma and advanced adenoma, we evaluated whether a positive FOBT or male sex is a stronger risk factor for adenoma and advanced adenoma. FOBT and screening colonoscopy results from 18.665 consecutive patients participating in a "national health check program" between 2009 and 2011 were included in this cohort study. Age-corrected adenoma detection rates (ADR), advanced adenoma detection rates (AADR) and carcinoma detection rates were calculated for men and women according to FOBT result separately. ADR and AADR in FOBT-positive men (34.6 and 11.8 %) and FOBT-negative men (29.1 and 7.6 %) were higher than ADR and AADR in FOBT-positive women (20 and 6.9 %) and in FOBT-negative women (17.6 and 4.4 %), (p = 0.0003). Men with negative FOBT were at higher risk of having an adenoma and advanced adenoma than women with positive FOBT (p < 0.0001). Odds ratios of a positive FOBT for ADR and AADR were 1.3 (1.1-1.5) (p = 0.0047) and 1.6 (1.2-2.1) (p < 0.0001), respectively. Odds ratios of male sex to predict ADR and AADR were significantly higher with 1.9 (1.8-2.1) and 1.8 (1.6-2), respectively (p < 0.001). Male sex is a stronger predictor for colorectal adenoma and advanced adenoma than positive FOBT. These results should be taken into account analyzing FOBT-based screening programs.

Fecal immunochemical test accuracy in average-risk colorectal cancer screening

AIM: To assess the fecal immunochemical test (FIT) accuracy for colorectal cancer (CRC) and advanced neoplasia (AN) detection in CRC screening.

METHODS: We performed a multicentric, prospective, double blind study of diagnostic tests on asymptomatic average-risk individuals submitted to screening colonoscopy. Two stool samples were collected and the fecal hemoglobin concentration was determined in the first sample (FIT1) and the highest level of both samples (FITmax) using the OC-sensor™. Areas under the curve (AUC) for CRC and AN were calculated. The best FIT1 and FITmax cut-off values for CRC were determined. At this threshold, number needed to scope (NNS) to detect a CRC and an AN and the cost per lesion detected were calculated.

RESULTS: About 779 individuals were included. An AN was found in 97 (12.5%) individuals: a CRC in 5 (0.6%) and an advanced adenoma (≥ 10 mm, villous histology or high grade dysplasia) in 92 (11.9%) subjects. For CRC diagnosis, FIT1 AUC was 0.96 (95%CI: 0.95-0.98) and FITmax AUC was 0.95 (95%CI: 0.93-0.97). For AN, FIT1 and FITmax AUC were similar (0.72, 95%CI: 0.66-0.78 vs 0.73, 95%CI: 0.68-0.79, respectively, P = 0.34). Depending on the number of determinations and the positivity threshold cut-off used sensitivity for AN detection ranged between 28% and 42% and specificity between 91% and 97%. At the best cut-off point for CRC detection (115 ng/mL), the NNS to detect a CRC were 10.2 and 15.8; and the cost per CRC was 1814€ and 2985€ on FIT1 and FITmax strategies respectively. At this threshold the sensitivity, NNS and cost per AN detected were 30%, 1.76, and 306€, in FIT1 strategy, and 36%, 2.26€ and 426€, in FITmax strategy, respectively.

CONCLUSION: Performing two tests does not improve diagnostic accuracy, but increases cost and NNS to detect a lesion.

Population-based colorectal cancer screening: comparison of two fecal occult blood test

BACKGROUND

The aim of screening for colorectal cancer is to improve prognosis by the detection of cancer at its early stages. In order to inform the decision on the specific test to be used in the population-based program in the Basque Autonomous Region (Spain), we compared two immunochemical fecal occult blood quantitative tests (I-FOBT).

METHODS

Residents of selected study areas, aged 50-69 years, were invited to participate in the screening. Two tests based on latex agglutination (OC-Sensor and FOB Gold) were randomly assigned to different study areas. A colonoscopy was offered to patients with a positive test result. The cut-off point used to classify a result as positive, according to manufacturer's recommendations, was 100 ng/ml for both tests.

RESULTS

The invited population included 37,999 individuals. Participation rates were 61.8% (n = 11,162) for OC-Sensor and 59.1% (n = 11,786) for FOB Gold (p = 0.008). Positive rate for OC-Sensor was 6.6% (n = 737) and 8.5% (n = 1,002) for FOB Gold (p < 0.0001). Error rates were higher for FOB gold (2.3%) than for OC-Sensor (0.2%; p < 0.0001). Predictive positive value (PPV) for total malignant and premalignant lesions was 62.4% for OC-Sensor and 58.9% for FOB Gold (p = 0.137), respectively.

CONCLUSION

OC-Sensor test appears to be superior for I-FOBT-based colorectal cancer screening, given its acceptance, ease of use, associated small number of errors and its screening accuracy. FOB Gold on the other hand, has higher rate of positive values, with more colonoscopies performed, it shows higher detection incidence rates, but involves more false positives.

Population-based colorectal cancer screening: comparison of two fecal occult blood test

BACKGROUND

The aim of screening for colorectal cancer is to improve prognosis by the detection of cancer at its early stages. In order to inform the decision on the specific test to be used in the population-based program in the Basque Autonomous Region (Spain), we compared two immunochemical fecal occult blood quantitative tests (I-FOBT).

METHODS

Residents of selected study areas, aged 50-69 years, were invited to participate in the screening. Two tests based on latex agglutination (OC-Sensor and FOB Gold) were randomly assigned to different study areas. A colonoscopy was offered to patients with a positive test result. The cut-off point used to classify a result as positive, according to manufacturer's recommendations, was 100 ng/ml for both tests.

RESULTS

The invited population included 37,999 individuals. Participation rates were 61.8% (n = 11,162) for OC-Sensor and 59.1% (n = 11,786) for FOB Gold (p = 0.008). Positive rate for OC-Sensor was 6.6% (n = 737) and 8.5% (n = 1,002) for FOB Gold (p < 0.0001). Error rates were higher for FOB gold (2.3%) than for OC-Sensor (0.2%; p < 0.0001). Predictive positive value (PPV) for total malignant and premalignant lesions was 62.4% for OC-Sensor and 58.9% for FOB Gold (p = 0.137), respectively.

CONCLUSION

OC-Sensor test appears to be superior for I-FOBT-based colorectal cancer screening, given its acceptance, ease of use, associated small number of errors and its screening accuracy. FOB Gold on the other hand, has higher rate of positive values, with more colonoscopies performed, it shows higher detection incidence rates, but involves more false positives.

Use of a low cut-off value for the fecal immunochemical test enables better detection of proximal neoplasia

BACKGROUND

The advantage of the quantitative fecal immunochemical test (FIT) is the flexibility to set the positivity threshold. However, the diagnostic success of the FIT has not been compared for standard and low cut-off thresholds.

AIMS

The purpose of this study was to compare the diagnostic success of FIT for standard and low cut-off thresholds.

METHODS

In 2009 and 2010 a standard cut-off threshold (20 μg Hb/g feces) was used as positivity criterion for the FIT; in 2012 a low cut-off (10 μg Hb/g feces) was used. Diagnostic success was compared between the two groups.

RESULTS

Of the total of 14,289 participants, 195 (1.4 %) had positive FIT results. Positivity of the FIT was significantly higher in the low cut-off group than in the standard cut-off group (1.8 vs. 1.0 %, p = 0.000). Although detection of advanced neoplasia lesions was comparable, proximal neoplasia was more frequently detected in the low cut-off group (33.3 vs. 20.9 %, p = 0.016). With the low cut-off threshold, 39 (0.7 %) participants were also classified as having positive results, and 18 (46.2 %) of these had colorectal neoplasias. The number of positive results from the FIT was increased by 54.9 %, and detection of advanced neoplasia was increased by 60 % with the low cut-off threshold compared with the standard cut-off.

CONCLUSIONS

A low cut-off threshold for the FIT resulted in better detection of proximal neoplasia in population-based screening. These results indicate the cut-off threshold for positive FIT should be properly chosen and adjusted in colorectal cancer screening.

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.

Comparison of the performance of guaiac-based and two immunochemical fecal occult blood tests for identifying advanced colorectal neoplasia in Taiwan

OBJECTIVES

We aimed to evaluate the performance of fecal occult blood tests (FOBT) for the screening of colorectal cancer (CRC).

METHODS

We selected participants from a medical center in Taiwan, China from November 2009 to June 2011. All participants underwent screening colonoscopy and were asked to provide their stool samples for qualitative immunochemical FOBT (qlFIT), quantitative immunochemical FOBT (qnFIT) and the guaiac-based FOBT(GT). The receiver operating characteristic curve was utilized to determine the optimal cut-off value of qnFIT. We measured the detection ability of the FOBT for colonic polypoid lesions.

RESULTS

In all, 699 participants were enrolled in this study. For qnFIT, we found increased levels of fecal hemoglobin in participants with polyps ≥10 mm (251.0 ng/mL), villous-containing adenomas (98.7 ng/mL) and advanced adenomas (187.9 ng/mL). The optimal cut-off value for qnFIT was 25 ng/mL for detecting advanced colorectal neoplasms (ACRN). All three FOBT had a similar but low estimate in detecting small and tubular adenomatous polyps. The qnFIT had a better detection ability for large adenomas (positive likelihood ratio [PLR], 5.6 vs 3.1 vs 0.3) and adenomas with villous-components (PLR 3.7 vs 3.3 vs 0.3) than qlFIT and GT. For the ACRN group, qnFIT also showed the best screening ability with a sensitivity of 56.8%, accuracy of 86.7% and PLR 5.0.

CONCLUSIONS

Both qnFIT and qlFIT perform better than GT in detecting advanced adenomas and CRC in the Taiwanese population.

Superior diagnostic performance of faecal immunochemical tests for haemoglobin in a head-to-head comparison with guaiac based faecal occult blood test among 2235 participants of screening colonoscopy

There is increasing evidence that faecal immunochemical tests (FITs) for haemoglobin offer a number of advantages over traditional guaiac based faecal occult blood tests (gFOBTs). However, evidence on diagnostic performance from direct comparisons with colonoscopy findings in all participants in the average risk population is still sparse. We aimed for a head-to-head comparison of three quantitative FITs with a gFOBT among participants of the German screening colonoscopy programme. Pre-colonoscopy stool samples and colonoscopy reports were obtained from 2235 participants of screening colonoscopy in 2005-2009. To enhance comparability of diagnostic performance of the various tests, we assessed sensitivity, specificity, predictive values and likelihood ratios of FITs after adjusting the FIT cut-off haemoglobin (Hb) concentrations in such a way that FIT positivity rates equalled the positivity rate of the gFOBT. Colorectal cancer, advanced adenomas and other adenomas were found in 15 (0.7%), 207 (9.3%) and 398 (17.8%) participants. The gFOBT was positive in 111 (5.0%) participants, with sensitivities (specificities) for detecting colorectal cancer, any advanced neoplasm or any neoplasm of 33.3% (95.2%), 8.6% (95.4%) and 5.5% (95.2%). At the same positivity rate, all three FITs outperformed the gFOBT in all indicators. In particular, all sensitivities of FITs were approximately two to three times higher at increased levels of specificity. All differences were statistically significant, except for some of the performance indicators for colorectal cancer. In conclusion, FITs can detect much larger proportions of colorectal neoplasms even if their cut-offs are set to levels that ensure equally low positivity rates as gFOBT.

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.

Colorectal cancer screening: why immunochemical fecal occult blood tests may be the best option

BACKGROUND

There are many test options available for colorectal cancer screening. The choice of test relates to the objectives of those offering or considering screening.

DISCUSSION

While all screening programs aim to detect disease early in order to improve the length and/or quality of life for the individual, some organizations and individuals prefer screening tests that offer the opportunity for cancer prevention. Others favor maximizing participation or the opportunity for shared decision-making, including discussion of information on test quality and availability. We propose three additional objectives for screening: minimizing harms, optimizing economic efficiency and maximizing equity of access to screening.

SUMMARY

Applying these objectives to colorectal cancer screening, we advocate the use of immunochemical FOBTs as the preferred screening strategy, as it satisfies all three of these important objectives.

[Korean guidelines for colorectal cancer screening and polyp detection]

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

Population-based screening for colorectal cancer using an immunochemical faecal occult blood test: a comparison of two invitation strategies

BACKGROUND

To date, there is no screening programme for colorectal cancer (CRC) in Flanders, Belgium. However, The European Code Against Cancer (2003) recommends a population-based approach for CRC screening. This study aimed to obtain information about potential participation rates for a population-based screening programme for CRC in Flanders, and to compare two invitation strategies.

METHODS

In 2009, a trial programme for CRC screening was set up in three Flemish areas for all average-risk people aged 50-74 years, using an immunochemical faecal occult blood test (iFOBT) with a cut-off value set at 75 ng/ml of haemoglobin. The faecal sampling set was sent at random by post (mail group) or provided by the general practitioner (GP group).

RESULTS

In total, 19,542 people were invited to participate. Of these, 8229 provided a faecal sample, resulting in an overall participation rate of 42.1%. Participation by mail and through the GP was 52.3% (95% CI, 51.3-53.2) and 27.7% (95% CI, 26.7-28.6), respectively. The difference of 24.6% was statistically significant (95% CI, 23.3-25.9, p<0.001). Before the reminder letter was sent and the other invitation strategy was offered, the overall participation rate was 26.5% (n=5176); 36.4% (95% CI, 35.5-37.4) for the mail group and 16.6% (95% CI, 15.8-17.3) for the GP group. The odds of participating in CRC screening was almost three times higher for people invited by mail as opposed to people invited through a GP (OR=2.96, 95% CI, 2.78-3.14, p<0.001). Women were more likely to participate in CRC screening than men (OR=1.22, 95% CI, 1.15-1.30, p<0.001). In addition, we found that inhabitants from residential (OR=1.98, 95% CI, 1.85-2.11) and rural (OR=2.90, 95% CI, 2.66-3.16) areas were more likely to participate than those in urban areas. Of the 8229 people who submitted a faecal sample, 435 (5.3%) had a positive iFOBT, and of those, CRC was diagnosed in 18 (5.7%) individuals. Compliance for follow-up colonoscopy was 72.9%, and did not differ between the mail (72.4%, 95% CI, 67.5-77.3) and GP groups (74.3, 95% CI, 66.2-82.5).

CONCLUSION

Inviting people for CRC screening by means of a direct-mail invitation, and including a faecal sampling set (iFOBT), results in much higher participation rates than inviting people through the GP.

Korean guidelines for colorectal cancer screening and polyp detection

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

Screening for colorectal cancer: sense and sensibilities

PURPOSE

In this paper we investigate the reasons for non-participation in a trial programme for colorectal cancer (CRC) screening in Flanders. Besides, the feasibility and possibilities of a full-blown screening programme in Flanders are examined, given the context of a low participation rate in breast cancer screening.

METHODS

A trial programme for CRC screening was set up for all average-risk persons aged 50 to 74 years in three Flemish regions to obtain information about potential participation rates, and to compare two invitation strategies. Faecal samples were analysed for precursors of CRC using an immunochemical faecal occult blood test (iFOBT). A questionnaire was administered to participants and non-participants of the trial programme to find out whether and to what extent the taking of a sample of one's own stool is a taboo. This could be of great importance concerning the participation rate.

RESULTS

In total, 19,542 persons were invited to participate in the trial programme for CRC screening, of whom 18,541 were found to be eligible. The overall participation rate was 44.3%. The three regions varied in participation rates: with 60.9% in the most rural region to 34.3% in the most urban region. Of 2,000 questionnaires sent to participants, 1,385 were returned (69.3%). The response in the non-participants was 43.2%i (691 questionnaires of 1,600 returned).

CONCLUSIONS

A population-based screening programme for colorectal cancer by means of an iFOBT proves to be feasible, since adequate participation rates were obtained and because of the absence of a 'stool taboo' in Flanders.

A comparative case study of bowel cancer screening in the UK and Australia: evidence lost in translation?

OBJECTIVES

(i) To document the current state of the English, Scottish, Welsh, Northern Irish and Australian bowel cancer screening programmes, according to seven key characteristics, and (ii) to explore the policy trade-offs resulting from inadequate funding.

SETTING

United Kingdom and Australia.

METHODS

A comparative case study design using document and key informant interview analysis. Data were collated for each national jurisdiction on seven key programme characteristics: screening frequency, population coverage, quality of test, programme model, quality of follow-up, quality of colonoscopy and quality of data collection. A list of optimal features for each of the seven characteristics was compiled, based on the FOBT screening literature and our detailed examination of each programme.

RESULTS

Each country made different implementation choices or trade-offs intended to conserve costs and/or manage limited and expensive resources. The overall outcome of these trade-offs was probable lower programme effectiveness as a result of compromises such as reduced screening frequency, restricted target age range, the use of less accurate tests, the deliberate setting of low programme positivity rates or increased inconvenience to participants from re-testing.

CONCLUSIONS

Insufficient funding has forced programme administrators to make trade-offs that may undermine the potential net population benefits achieved in randomized controlled trials. Such policy compromise contravenes the principle of evidence-based practice which is dependent on adequate funding being made available.

A higher detection rate for colorectal cancer and advanced adenomatous polyp for screening with immunochemical fecal occult blood test than guaiac fecal occult blood test, despite lower compliance rate. A prospective, controlled, feasibility study

Immunochemical fecal occult blood test (FIT) is a new colorectal cancer (CRC) screening method already recommended by the American screening guidelines. We aimed to test the feasibility of FIT as compared to guaiac fecal occult blood test (G-FOBT) in a large urban population of Tel Aviv. Average-risk persons, aged 50-75 years, were offered FIT or G-FOBT after randomization according to the socioeconomic status of their clinics. Participants with positive tests underwent colonoscopy. Participants were followed through the Cancer Registry 2 years after the study. Hemoccult SENSA™ and OC-MICRO™ (three samples, 70 ng/ml threshold) were used. FIT was offered to 4,657 persons (Group A) and G-FOBT to 7,880 persons (Group B). Participation rate was 25.9% and 28.8% in Group A and B, respectively (p < 0.001). Positivity rate in Group A and B was 12.7% and 3.9%, respectively (p < 0.001). Cancer found in six (0.49%) and eight (0.35%) patients of Group A and B, respectively (NS). Cancer registry follow-up found missed cancer in five (0.22%) cases of Group B and none in Group A (NS). The sensitivity, specificity, negative and positive predictive value for cancer in Group A and B were 100%, 85.9%, 100%, 3.9% and 61.5%, 96.4%, 99.8%, 9.1%, respectively. There was increased detection of advanced adenomatous polyp (AAP) by FIT, irrespective of age, gender, and socioeconomic status (Per Protocol: odds ratio 2.69, 95% confidence interval 1.6-4.5; Intention to Screen: odds ratio 3.16, 95% confidence interval 1.8-5.4). FIT is feasible in urban, average-risk population, which significantly improved performance for detection of AAP and CRC, despite reduced participation.

Novel methylation panel for the early detection of colorectal tumors in stool DNA

BACKGROUND

Previous studies showed that the assessment of promoter hypermethylation of a limited number of genes in tumor biopsies may identify the majority of colorectal tumors. This study aimed to assess the clinical usefulness of a panel of methylation biomarkers in stool DNA in the identification of colorectal tumors, using methylation-specific melting curve analysis (MS-MCA), a technique that simultaneously analyzes all cytosine-phosphate-guanine (CpG) residues within a promoter.

MATERIALS AND METHODS

The promoter methylation status of 4 tumor-related genes (RARB2, p16INK4a, MGMT, and APC) was analyzed in DNA stool samples and corresponding tissues in an initial set of 12 patients with newly diagnosed primary colorectal carcinomas and 20 patients with newly diagnosed colorectal adenomas, using methylation-specific polymerase chain reaction. Results were replicated in a set of 82 patients (20 healthy subjects, 16 patients with inflammatory bowel disease (IBD), 20 patients with adenomas, and 26 patients with carcinomas), using MS-MCA analyses.

RESULTS

In the initial set, >or= 1 positive methylation marker was detected in the stools of 9 of 12 patients (75%) with carcinomas and 12 of 20 patients (60%) with adenomas, with no false-positive results. Stool analyses missed 7 methylated lesions (25%). In the replication set, stool DNA testing detected 16 of 26 carcinomas (62%) and 8 of 20 adenomas (40%). The MS-MCAs missed 14 methylated tumors (37%). No aberrant methylation was evident in healthy subjects, but the RARB2 marker was positive in 2 of 15 stool samples (13%) of patients with IBD.

CONCLUSION

Analysis via MS-MCA of a panel of methylation markers in stool DNA may offer a good alternative in the early, noninvasive detection of colorectal tumors.

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.

Comparison of immunochemical and guaiac-based fecal occult blood test in screening and surveillance for advanced colorectal neoplasms: a meta-analysis

OBJECTIVE

To systematically evaluate whether immunochemical fecal occult blood tests (iFOBT) could improve clinical performance and test accuracy in screening and surveillance for advanced colorectal neoplasms.

METHODS

Eligible articles were identified by searches of electronic databases. All randomized trials and diagnostic cohort trials directly comparing iFOBT with guaiac-based FOBT (gFOBT) were included. A statistical analysis was performed using RevMan 4.2.8. A sensitivity, specificity and summary receiver operating characteristic curve was performed using Meta Disc.

RESULTS

We identified five randomized trials and 11 diagnostic cohort trials. In the randomized trials, the detection rates of advanced colorectal neoplasms with iFOBT or gFOBT were 2.23 percent and 1.24 percent, respectively. The pooled odds ratio (OR) was 1.50 (95% CI 0.94-2.39). In cohort trials, the advanced neoplasm detection rates of iFOBT or gFOBT were 1.44 percent and 0.50 percent (OR 1.99, 95% CI 1.24-3.19) in the average-risk screened population, and were 8.8 percent and 7.1 percent (OR 1.27, 95% CI 1.01-1.60) in diagnosed patients scheduled for colonoscopy. The sensitivity of iFOBT (0.67, 95% CI 0.61-0.73) was superior to that of gFOBT (0.54, 95% CI 0.48-0.60), as well as the specificities (0.85, 95% CI 0.83-0.87 vs 0.80, 95% CI 0.78-0.82) and positive predictive values (0.41 vs 0.29) in cohort trials of diagnosed patients.

CONCLUSION

Our review suggests that iFOBT could perform better in increasing the detection rate of advanced colorectal neoplasm than gFOBT and possesses higher sensitivity and specificity in the surveillance of advanced colorectal neoplasm for patients.

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.

Can patients at high risk for significant colorectal neoplasms and having normal quantitative faecal occult blood test postpone elective colonoscopy?

BACKGROUND

Common reasons for elective screening and surveillance colonoscopy, at predetermined intervals, are family or personal history of colorectal cancer (CRC) or advanced adenoma (AAP). Quantified, human haemoglobin (Hb)-specific, immunochemical faecal occult blood tests (I-FOBT) detect bleeding.

AIM

To determine I-FOBT sensitivity for CRC or AAP before elective colonoscopy in patients at high-risk of cancer or advanced adenoma.

METHODS

Prospective double-blind study of 1000 ambulatory asymptomatic high-risk patients (555 family history of CRC, 445 surveillance for past neoplasm), who prepared three I-FOBTs before elective colonoscopy. I-FOBTs quantified as ngHb/mL of buffer by OC-MICRO instrument and results >or=50 ngHb/mL considered positive.

RESULTS

At colonoscopy, eight patients had CRC, 64 others had AAP. Sensitivity for CRC and/or AAP was the highest, 65.3% (95% CI 54.3, 76.3), when any of the three I-FOBTs was >or=50 ngHb (15.4%), with specificity of 87.5% (95% CI 86.4, 90.5) identifying all CRCs and 62% of AAPs.

CONCLUSIONS

All cancers or an AAP were detected every third I-FOBT-positive colonoscopy (47/154), so colonoscopy was potentially not needed at this time in 84.6% (846 patients). I-FOBT screening might provide effective supervision of high-risk patients, delaying unnecessary elective colonoscopies. This favourable evaluation needs confirmation and cost-benefit study by risk-group.

Perspectives of colorectal cancer screening in Germany 2009

Adequate screening methods can decrease colorectal cancer (CRC) mortality. The guaiac test for fecal occult-blood (FOBT) is part of the German CRC Screening Program since 1970 and has evidence level Ia. In randomized multicenter-studies FOBT has an average sensitivity of 24% and decreases CRC mortality up to 30%. Immunological tests for human haemoglobin (iFOBT) show better performance characteristics than guaiac FOBT, with augmented sensitivity and specificity. However, the single tests show wide differences in diagnostic performance and iFOBT is not yet covered by insurance companies although it should replace the guaiac test for CRC screening. Visual colonoscopy, which was introduced to the German National Cancer Screening Program in 2002, is the gold standard for the diagnosis of colorectal neoplasia. From 2003 to 2007 more than 2.8 million examinations have been documented in Germany. The prevalence of adenomas is around 20% and of CRC about 0.7% to 1.0% of the screenings. Seventy percent of the carcinomas detected during screening are in an early stage (UICC I and II). Furthermore, screening colonoscopy is a cost saving procedure with a low complication rate (0.25% overall). Insurance companies save 216€ for each screening colonoscopy mainly by prevention of neoplasia due to polypectomy. In Germany, virtual colonography by computed tomography (CT) or magnetic resonance imaging still lacks standardization of the hard and software. In experienced centres the sensitivity for CRC and large polyps of CT colonography is comparable to colonoscopy but in meta-analyses the ranking is lower. New technologies like computer-aided colonoscopies with sheath or double balloon techniques are coming up as well as capsule colonoscopy, which sensitivity for large polyps is about 70%. Advised by his physician, the patient can choose his most acceptable examination method from this whole set of screening tools.

Colon cancer screening and surveillance controversies

PURPOSE OF REVIEW

To discuss new colorectal cancer screening tests and highlight controversies regarding colon screening and surveillance.

RECENT FINDINGS

New screening guidelines were published in 2008. Tests that primarily detect early cancer include sensitive guaiac fecal occult blood test or fecal immunochemical test. Tests that can detect both early cancer and cancer precursor lesions include sigmoidoscopy and colonoscopy. One guideline endorses the use of computed tomographic colonography. Limitations of each test are highlighted in the new guidelines. Controversies include age to start screening, age to stop screening, and appropriate interval after a negative screening colonoscopy. New work has raised some doubt about the protective effect of colonoscopy in the proximal colon. Finally, there is new emphasis on the quality of screening programs.

SUMMARY

Colorectal cancer screening can reduce both incidence and mortality of colorectal cancer if performed with high quality. New work should focus on improving the quality of all screening programs.

[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.

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.