Colorectal cancer screening by detection of altered human DNA in stool: feasibility of a multitarget assay panel

Focus on genetic and epigenetic events of colorectal cancer pathogenesis: implications for molecular diagnosis

Originally, colorectal cancer (CRC) tumorigenesis was understood as a multistep process that involved accumulation of tumor suppressor genes and oncogenes mutations, such as APC, TP53 and KRAS. However, this assumption proposed a relatively limited repertoire of genetic alterations. In the last decade, there have been major advances in knowledge of multiple molecular pathways involved in CRC pathogenesis, particularly regarding cytogenetic and epigenetic events. Microsatellite instability, chromosomal instability and CpG island methylator phenotype are the most analyzed cytogenetic changes, while DNA methylation, modifications in histone proteins and microRNAs (miRNAs) were analyzed in the field of epigenetic alterations. Therefore, CRC development results from interactions at many levels between genetic and epigenetic amendments. Furthermore, hereditary cancer syndrome and individual or environmental risk factors should not be ignored. The difficulties in this setting are addressed to understand the molecular basis of individual susceptibility to CRC and to determine the roles of genetic and epigenetic alterations, in order to yield more effective prevention strategies in CRC patients and directing their treatment. This review summarizes the most investigated biomolecular pathways involved in CRC pathogenesis, their role as biomarkers for early CRC diagnosis and their possible use to stratify susceptible patients into appropriate screening or surveillance programs.

Population screening for colorectal cancer means getting FIT: the past, present, and future of colorectal cancer screening using the fecal immunochemical test for hemoglobin (FIT)

Fecal immunochemical tests for hemoglobin (FIT) are changing the manner in which colorectal cancer (CRC) is screened. Although these tests are being performed worldwide, why is this test different from its predecessors? What evidence supports its adoption? How can this evidence best be used? This review addresses these questions and provides an understanding of FIT theory and practices to expedite international efforts to implement the use of FIT in CRC screening.

miRNA as markers for the diagnostic screening of colon cancer

Early screening for colon cancer (CC) allows for early stage diagnosis of the malignancy and potentially reduces disease mortality as the cancer is most likely curable at its earliest stages. Early detection would be desirable if accurate, practical and cost-effective diagnostic measures for this cancer were available. Mortality and morbidity from CC represent a major health problem involving a malignant disease that is theoretically preventable through screening. Current screening methods (e.g., the convenient and inexpensive immunological fecal occult blood test, FOBTi, obtained from patients' medical records) either lack sensitivity and require dietary restriction, which impedes compliance and use; are costly (e.g., colonoscopy), which decreases compliance; or could result in mortality. In comparison with the FOBT test, a non-invasive sensitive screen for which there is no requirement for dietary restriction would be a more convenient test. Colorectal cancer is the only cancer for which colonoscopy is recommended as a screening method. Although colonoscopy is a reliable screening tool, the invasive nature, abdominal pain, potential complications and high cost have hampered the application of this procedure worldwide. A screening approach using the stable miRNA molecules, which are relatively non-degradable when extracted from non-invasive stool and semi-invasive blood samples by commercially available kits and manipulated thereafter, would be preferable to a transcriptomic mRNA-, a mutation DNA-, an epigenetic- or a proteomic-based test. The approach uses reverse transcriptase, modified real-time quantitative PCR. Although exosomal RNA would be missed, using a restricted extraction of total RNA from stool or blood, a parallel test could also be carried out on RNA obtained from stool or plasma samples, and appropriate corrections for exsosomal loss can be made for accurate and quantitative test result. Eventually, a chip can be developed to facilitate diagnosis, as has been done for the quantification of genetically modified organisms in foods. The gold standard to which the molecular miRNA test is compared is colonoscopy, which can be obtained from patients' medical records. If performance criteria are met, as detailed herein, a miRNA test in human stool or blood samples based on high-throughput automated technologies and quantitative expression measurements commonly used in the diagnostic clinical laboratory should be advanced to the clinical setting, which will make a significant impact on CC prevention.

Competition in Colon Cancer Screening? What Is the Role of Colonoscopy?

BACKGROUND

Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the Western world. The incidence could be reduced if this cancer were to be diagnosed at an early stage of disease. A competition has started between the existing screening methods to be the most efficient in detecting premalignant conditions. This review illustrates the current state of screening techniques for CRC.

METHOD

Pubmed was searched for meta-analyses and prospective studies on screening for CRC, with an emphasis on colonography, computed tomographic colonography (CTC), magnetic resonance colonography (MRC), stool DNA testing, and colon capsule endoscopy, and critical appraisal of the research was done by the reviewers.

RESULTS

The imaging techniques (CTC and MRC) had similar detection rates for bigger lesions (≥10 mm) as colonoscopy. High-definition colonoscopy showed better efficiency with smaller lesions. The techniques developing around colonoscopy such as the retro-viewing colonoscope, the balloon colonoscope, or the 330-degree viewing colonoscope try to enhance efficacy by reducing the adenoma miss rate in right-sided, non-polypoid lesions. Colon capsule endoscopy and the stool detection systems are limited to identifying cancer but not necessarily adenomas.

CONCLUSION

Colonoscopy is the preferred CRC screening strategy and the undisputed gold standard in terms of efficacy.

Colorectal cancer: screening and surveillance for high-risk individuals

Colorectal cancer is very common and is closely related to patient age. After age, the second most common risk factor is family history of colon cancer. In fact, it is one of the most hereditable cancers. Colon cancer is preventable and screening has demonstrated efficacy in the reduction of both the incidence and the mortality from colorectal cancer. Several screening techniques are currently available, including endoscopy and nonendoscopic-based techniques. Screening strategies vary according to the individual risk of colon cancer. This paper will focus on the screening recommendations for patients with high-risk colon cancer.

New molecular diagnosis and screening methods for colorectal cancer using fecal protein, DNA and RNA

Several screening methods for reducing the mortality rate of colorectal cancer (CRC) have been reported in recent decades. Fecal occult blood tests (FOBTs) are widely used for CRC screening and immunochemical FOBTs perform better than guaiac FOBTs; however, the sensitivity and specificity of immunochemical FOBTs remain unsatisfactory. To resolve this problem, novel fecal molecular methods based on fecal protein, DNA and RNA analyses have been developed. Regarding fecal proteins, several marker proteins indicating intestinal bleeding and cancer cell-specific proteins have been investigated. Regarding fecal DNA, numerous gene mutation and gene methylation analyses have been reported. Consequently, fecal DNA analysis was recommended as a CRC screening method in 2008. In addition, gene expression analyses of CRC-specific genes and miRNAs in fecal RNA have been investigated over the last decade. This review article summarizes molecular methods using fecal samples for CRC screening, focusing on reports within the last 5 years.

Diagnostic value of stool DNA testing for multiple markers of colorectal cancer and advanced adenoma: a meta-analysis

BACKGROUND AND OBJECTIVES

The diagnostic value of stool DNA (sDNA) testing for colorectal neoplasms remains controversial. To compensate for the lack of large-scale unbiased population studies, a meta-analysis was performed to evaluate the diagnostic value of sDNA testing for multiple markers of colorectal cancer (CRC) and advanced adenoma.

METHODS

The PubMed, Science Direct, Biosis Review, Cochrane Library and Embase databases were systematically searched in January 2012 without time restriction. Meta-analysis was performed using a random-effects model using sensitivity, specificity, diagnostic OR (DOR), summary ROC curves, area under the curve (AUC), and 95% CIs as effect measures. Heterogeneity was measured using the χ(2) test and Q statistic; subgroup analysis was also conducted.

RESULTS

A total of 20 studies comprising 5876 individuals were eligible. There was no heterogeneity for CRC, but adenoma and advanced adenoma harboured considerable heterogeneity influenced by risk classification and various detection markers. Stratification analysis according to risk classification showed that multiple markers had a high DOR for the high-risk subgroups of both CRC (sensitivity 0.759 [95% CI 0.711 to 0.804]; specificity 0.883 [95% CI 0.846 to 0.913]; AUC 0.906) and advanced adenoma (sensitivity 0.683 [95% CI 0.584 to 0.771]; specificity 0.918 [95% CI 0.866 to 0.954]; AUC 0.946) but not for the average-risk subgroups of either. In the methylation subgroup, sDNA testing had significantly higher DOR for CRC (sensitivity 0.753 [95% CI 0.685 to 0.812]; specificity 0.913 [95% CI 0.860 to 0.950]; AUC 0.918) and advanced adenoma (sensitivity 0.623 [95% CI 0.527 to 0.712]; specificity 0.926 [95% CI 0.882 to 0.958]; AUC 0.910) compared with the mutation subgroup. There was no significant heterogeneity among studies for subgroup analysis.

CONCLUSION

sDNA testing for multiple markers had strong diagnostic significance for CRC and advanced adenoma in high-risk subjects. Methylation makers had more diagnostic value than mutation markers.

DNA quantification of exfoliated colonocytes as a novel screening tool for colorectal cancer

AIMS

Colorectal cancer (CRC) sheds viable cells in the mucocelluar layer overlaying the colonic mucosa which travels distally alongside the faecal stream. These cells can be retrieved from the surface of the rectal mucosa. DNA quantification of these cells may be a marker of CRC, assessment of which was aim of this study.

METHODS

A prospective double-blinded study of 467 consecutive patients referred with symptoms suggestive of CRC. Cells were collected from the surface of the rectal mucosa and total DNA quantified. DNA scores were compared with outcome after subjects had completed bowel investigations. Analysis of receiver operating characteristic (ROC) curves was performed to determine the optimum cut-off point for a positive result.

RESULTS

107 of the 467 patients were excluded due to; excessive faecal contamination of samples (n = 84); declined investigations (n = 17); inappropriate referral (n = 5); unfit (n = 1). 263 patients had lower GI endoscopy; 89 CT colonography and 8 barium enema. The diagnosis were; CRC (n = 23), inflammatory bowel disease (IBD) (n = 7), adenomatous polyps (AP) (n = 20) and no significant abnormality detected (n = 310). ROC analysis revealed that sensitivities at a specificity of 60% for detecting CRC were 91.3%; for CRC and IBD 86.7%; and for CRC, IBD and AP 72.0%.

CONCLUSION

In symptomatic patients DNA quantification of cells retrieved from the surface of the rectal mucosa is sensitive for the detection of CRC. Although faecal contamination is a limitation of this technique, refinement and application of other molecular tests hold promise for a better non invasive method for the detection of CRC.

Differential expression of carbohydrate antigen 19-9 in human colorectal cancer: A comparison with colon and rectal cancers

Colorectal cancer is one of the leading causes of cancer-related mortality, being the third most commonly diagnosed cancer among men and the second among women. Accumulating evidence regarding carbohydrate antigen (CA) demonstrated that tumor-associated antigens are clinically useful for the diagnosis, staging and monitoring of human gastrointestinal cancers, particularly colorectal cancer. There has been an extensive investigation for sensitive and specific markers of this disease. Currently, the gastrointestinal cancer-associated carbohydrate antigen 19-9 (CA19-9) is the most widely applied tumor marker in cancer diagnosis. Despite a similar etiology and cancer incidence rates, there are anatomical and clinical differences between colon and rectal cancer, as well as differences regarding tumor progression and adjuvant treatments. To investigate whether CA19-9 is differentially expressed between colon and rectal cancer, we conducted a differential analysis of serum CA19-9 levels among 227 cases of colorectal cancer, analyzing gender, age, Dukes' stage and distant metastasis for human colon and rectal cancer as a single entity, separately and as matched pairs. We demonstrated that the serum CA19-9 levels in colorectal cancer were upregulated in advanced stages with distant metastasis. By contrast, the serum CA19-9 levels in colon cancer displayed a differential and upregulated behavior in advanced stages with distant metastasis. By analyzing as matched pairs, the upregulated serum CA19-9 levels in rectal cancer during the early stages without distant metastasis further supported our hypothesis that the expression of CA19-9 displays a site-specific differential behavior. The integrative analysis suggested a significant difference between human colon and rectal cancer, justifying individualized therapy for these two types of cancer.

Detection of hypermethylated fibrillin-1 in the stool samples of colorectal cancer patients

Prior studies have demonstrated that analysis of gene promoter methylation in stool samples may be a potential biomarker for noninvasive colorectal cancer detection. Aberrant methylation in gene promoter is common in various cancers, and epigenetic alterations can result in down-regulation or silence of gene expression. Recently, hypermethylation of fibrillin-1 (FBN1) was reported to be associated with colorectal cancer (CRC). In this study, we examined the methylation status of FBN1 in stool samples to test CRC. For the purpose of colorectal cancer detection, we investigated FBN1 hypermethylation in the tissue and stool samples of colorectal cancer patients using methylation-specific polymerase chain reaction. The result is that out of 75 patients with colorectal cancer, 59 (78.7%) exhibited hypermethylated FBN1 in their tumor tissue DNA. We next detected the methylation status of FBN1 in the stool DNA of these patients. The hypermethylated FBN1 occurred in 72% (54/75) of these patients in their stool samples and occurred in 6.7% (2/30) of healthy people (P < 0.001). The results indicated 72.0% sensitivity and 93.3% specificity of the test for detecting CRC by using stool samples. So, the study reveals that hypermethylation status in the promoter of FBN1 is a high specific and sensitive biomarker for colorectal cancer, and detecting hypermethylated FBNI in stool samples is a noninvasive and useful method for screening colorectal cancer.

Cancer markers: integratively annotated classification

Translational cancer genomics research aims to ensure that experimental knowledge is subject to computational analysis, and integrated with a variety of records from omics and clinical sources. The data retrieval from such sources is not trivial, due to their redundancy and heterogeneity, and the presence of false evidence. In silico marker identification, therefore, remains a complex task that is mainly motivated by the impact that target identification from the elucidation of gene co-expression dynamics and regulation mechanisms, combined with the discovery of genotype-phenotype associations, may have for clinical validation. Based on the reuse of publicly available gene expression data, our aim is to propose cancer marker classification by integrating the prediction power of multiple annotation sources. In particular, with reference to the functional annotation for colorectal markers, we indicate a classification of markers into diagnostic and prognostic classes combined with susceptibility and risk factors.

Molecular biomarkers in esophageal, gastric, and colorectal adenocarcinoma

Cancers of the esophagus, stomach and colon contribute to a major health burden worldwide and over 20% of all cancer deaths. Biomarkers that should indicate pathogenic process and are measureable in an objective manner for these tumors are rare and not established in the clinical setting. In general biomarkers can be very useful for cancer management as they can improve clinical decision-making regarding diagnosis, surveillance, and therapy. Biomarkers can be different types of molecular entities (such as DNA, RNA or proteins), which can be detected, in different tissues or body fluids. However, more important is the type of biomarker itself, which allows diagnostic, prognostic or predictive analyses for different clinical problems. This review aims to systematically summarize the recent findings of genetic and epigenetic markers for gastrointestinal tumors within the last decade. While many biomarkers seem to be very promising, especially if used as panels, further development is urgently needed to address practical considerations of biomarkers in cancer treatment.

Cost effectiveness of fecal DNA screening for colorectal cancer: a systematic review and quality appraisal of the literature

BACKGROUND

Fecal DNA (fDNA) testing is a noninvasive potential alternative to current colorectal cancer screening tests.

OBJECTIVE

We conducted a systematic review and quality assessment of studies of cost-effectiveness of fDNA as a colorectal cancer screening tool (compared with no screening and other screening modalities), and identified key variables that impinged on cost-effectiveness.

DATA SOURCES

We searched MEDLINE, Embase, and the Centre for Reviews and Dissemination for cost-effectiveness studies of fDNA-based screening, published in English by September 2011.

STUDY SELECTION

Studies that undertook an economic evaluation of fDNA, using either a cost-effectiveness or cost-utility analysis, compared with other relevant screening modalities and/or no screening were included. Additional inclusion criteria related to the presentation of data pertaining to model variables including time horizon, costs, fDNA performance characteristics, screening uptake, and comparators. A total of 369 articles were initially identified for review. After removing duplicates and applying inclusion and exclusion criteria, seven articles were included in the final review.

STUDY APPRAISAL

Data was abstracted on key descriptor variables including screening scenarios, time horizon, costs, test performance characteristics, screening uptake, comparators, and incremental cost-effectiveness ratios. Quality assessment was undertaken using a standard checklist for economic evaluations. Studies cited by cost-effectiveness articles as the source of data on fDNA test performance characteristics were also reviewed.

RESULTS

Seven cost-effectiveness studies were included, from the USA (4), Canada (1), Israel (1), and Taiwan (1). Markov models (5), a partially observable Markov decision process model (1) and MISCAN and SimCRC (1) microsimulation models were used. All studies took a third-party payer perspective and one included, in addition, a societal perspective. Comparator screening tests, screening intervals, and specific fDNA tests varied between studies. fDNA sensitivity and specificity parameters were derived from 12 research studies and one meta-analysis. Outcomes assessed were life-years gained and quality-adjusted life-years gained. fDNA was cost-effective when compared with no screening in six studies. Compared with other screening modalities, fDNA was not considered cost-effective in any of the base-case analyses: in five studies it was dominated by all alternatives considered. Sensitivity analyses identified cost, compliance, and test parameters as key influential parameters. In general, poor presentation of "study design" and "data collection" details lowered the quality of included articles.

LIMITATIONS

Although the literature searches were designed for high sensitivity, the possibility cannot be excluded that some eligible studies may have been missed. Reports (such as Health Technology Assessments produced by government agencies) and other forms of grey literature were excluded because they are difficult to identify systematically and/or may not report methods and results in sufficient detail for assessment.

CONCLUSION

On the basis of the available (albeit limited) evidence, while fDNA is cost-effective when compared with no screening, it is currently dominated by most of the other available screening options. Cost and test performance appear to be the main influences on cost-effectiveness.

Application of the fecal microRNA test to the residuum from the fecal occult blood test

OBJECTIVE

Though the fecal occult blood test is used for colorectal cancer screening worldwide, it does not have a particularly high sensitivity for detecting colorectal cancer. Here we investigated the applicability of the fecal microRNA test to fecal samples that had been used for a previous fecal occult blood test and stored under various conditions.

METHODS

Five colorectal cancer patients and five healthy volunteers were enrolled. Fecal samples were stored for 0-5 days at 4°C, room temperature or 37°C. Total RNA was extracted from the fecal occult blood test residuum and microRNA expression was analyzed by real-time reverse transcription polymerase chain reaction.

RESULTS

There were no remarkable differences either in colorectal cancer patients or in controls with regard to the concentration of RNA extracted from the fecal occult blood test residuum in any of the storage groups compared with the samples prepared on day 0 (Group 0). Ribosomal RNA stored at room temperature or 37°C degraded rapidly. In contrast, the ribosomal RNA stored at 4°C remained intact for at least 5 days. The microRNAs in samples stored at 4°C and room temperature were conserved; however, the microRNAs stored at 37°C were significantly degraded compared with Group 0 (P < 0.05). In the residuum stored at 4°C up to 5 days, the relative quantification of miR-106a normalized with miR-24 in colorectal cancer patients was significantly higher than those in healthy volunteers (P < 0.05). In contrast, the quantification of normalized miR-106a was remarkably low in samples stored at room temperature and 37°C.

CONCLUSIONS

Fecal microRNA of sufficient quality for reverse transcription polymerase chain reaction analysis was extracted from the fecal occult blood test residuum stored at 4°C for up to 5 days.

The Diagnostic and Prognostic Role of microRNA in Colorectal Cancer - a Comprehensive review

The discovery of microRNA, a group of regulatory short RNA fragments, has added a new dimension to the diagnosis and management of neoplastic diseases. Differential expression of microRNA in a unique pattern in a wide range of tumor types enables researches to develop a microRNA-based assay for source identification of metastatic disease of unknown origin. This is just one example of many microRNA-based cancer diagnostic and prognostic assays in various phases of clinical research.

Since colorectal cancer (CRC) is a phenotypic expression of multiple molecular pathways including chromosomal instability (CIN), micro-satellite instability (MIS) and CpG islands promoter hypermethylation (CIMP), there is no one-unique pattern of microRNA expression expected in this disease and indeed, there are multiple reports published, describing different patterns of microRNA expression in CRC.

The scope of this manuscript is to provide a comprehensive review of the scientific literature describing the dysregulation of and the potential role for microRNA in the management of CRC. A Pubmed search was conducted using the following MeSH terms, "microRNA" and "colorectal cancer". Of the 493 publications screened, there were 57 papers describing dysregulation of microRNA in CRC.

Colorectal cancer biomarkers and the potential role of cancer stem cells

Over 50% of patients with colorectal cancer (CRC) will progress and/or develop metastases. Biomarkers capable of predicting progression, risk stratification and therapeutic benefit are needed. Cancer stem cells are thought to be responsible for tumor initiation, dissemination and treatment failure. Therefore, we hypothesized that CRC stem cell markers (CRCSC) can identify a group of patients whom are at increased risk for recurrence or progression of disease. If proven correct, these CRCSC biomarkers may herald a paradigm shift in the treatment of this deadly disease. This manuscript reviews current CRC evidence based screening modalities, patient stratification, and summarizes the current state of biomarkers and discusses the novel concept of putative CRCSC's as prognostic biomarkers.

Exhaled volatile organic compounds identify patients with colorectal cancer

BACKGROUND

An effective screening tool for colorectal cancer is still lacking. Analysis of the volatile organic compounds (VOCs) linked to cancer is a new frontier in cancer screening, as tumour growth involves several metabolic changes leading to the production of specific compounds that can be detected in exhaled breath. This study investigated whether patients with colorectal cancer have a specific VOC pattern compared with the healthy population.

METHODS

Exhaled breath was collected in an inert bag (Tedlar(®) ) from patients with colorectal cancer and healthy controls (negative at colonoscopy), and processed offline by thermal-desorber gas chromatography-mass spectrometry to evaluate the VOC profile. During the trial phase VOCs of interest were identified and selected, and VOC patterns able to discriminate patients from controls were set up; in the validation phase their discriminant performance was tested on blinded samples. A probabilistic neural network (PNN) validated by the leave-one-out method was used to identify the pattern of VOCs that better discriminated between the two groups.

RESULTS

Some 37 patients and 41 controls were included in the trial phase. Application of a PNN to a pattern of 15 compounds showed a discriminant performance with a sensitivity of 86 per cent, a specificity of 83 per cent and an accuracy of 85 per cent (area under the receiver operating characteristic (ROC) curve 0·852). The accuracy of PNN analysis was confirmed in the validation phase on a further 25 subjects; the model correctly assigned 19 patients, giving an overall accuracy of 76 per cent.

CONCLUSION

The pattern of VOCs in patients with colorectal cancer was different from that in healthy controls. The PNN in this study was able to discriminate patients with colorectal cancer with an accuracy of over 75 per cent. Breath VOC analysis appears to have potential clinical application in colorectal cancer screening, although further studies are required to confirm its reliability in heterogeneous clinical settings.

Quantitative profiling of CpG island methylation in human stool for colorectal cancer detection

PURPOSE

The aims of this study were to investigate the use of quantitative CGI methylation data from stool DNA to classify colon cancer patients and to relate stool CGI methylation levels to those found in corresponding tissue samples.

METHODS

We applied a quantitative methylation-specific PCR assay to determine CGI methylation levels of six genes, previously shown to be aberrantly methylated during colorectal carcinogenesis. Assays were performed on DNA from biopsies of "normal" mucosa and stool samples from 57 patients classified as disease-free, adenoma, or cancer by endoscopy, and in tumour tissue from cancer patients. Additionally, CGI methylation was analysed in stool DNA from an asymptomatic population of individuals covering a broad age range (mean = 47 ± 24 years)

RESULTS

CGI methylation levels in stool DNA were significantly higher than in DNA from macroscopically normal mucosa, and a significant correlation between stool and mucosa was observed for ESR1 only. Multivariate statistical analyses using the methylation levels of each CGI in stool DNA as a continuous variable revealed a highly significant (p = 0.003) classification of cancer vs. non-cancer (adenoma + disease-free) patients (sensitivity = 65 %, specificity = 81 %).

CONCLUSION

CGI methylation profiling of stool DNA successfully identified patients with cancer despite the methylation status of CGIs in stool DNA not generally reflecting those in DNA from the colonic mucosa.

Noninvasive screening tests for colorectal cancer

BACKGROUND

Identifying an accurate, reliable, affordable, and acceptable noninvasive screening test for colorectal cancer (CRC) would greatly facilitate population screening.

METHODS

Published literature from 2000 through February 2012 on noninvasive CRC screening tests was identified, reviewed, and summarized.

RESULTS

The highest quality evidence for noninvasive screening exists for guaiac-based fecal occult blood tests (gFOBTs), for which the CRC-specific incidence and mortality reductions are modest. Fecal immunochemical tests (FITs) offer better sensitivity and comparable specificity. Cross-sectional studies comparing gFOBTs and FITs suggest that FITs provide higher detection of advanced neoplasia. Modeling studies favor FITs over gFOBTs with respect to effectiveness and cost-effectiveness. A myriad of studies report the performance of fecal-based and blood-based genetic and protein-based biomarkers; the studies differ in patient population assembled, marker selection, and assay methods. Several markers and panels of markers are promising, although nearly all studies focus on new markers and/or assay methods on small sets of referred patients rather than validating markers using optimal assays in a screening setting.

CONCLUSION

In the absence of long-term randomized trials, adoption of the noninvasive tests will require cross-sectional data on test characteristics obtained from the screening setting, where CRC prevalence is low and the full spectrum of colorectal findings exists, along with estimates of cumulative risks, benefits, and cost-effectiveness. Test adoption will ultimately depend on test characteristics, availability, affordability, and user appeal. There is no noninvasive substitute for the currently recommended screening tests. FITs should replace gFOBTs wherever gFOBTs are used for screening.

Colon cancer screening in women

Colorectal cancer is the third leading cause of cancer-related deaths in women. Colorectal cancer is a preventable disease with accepted screening modalities that have been proven to save lives. As women are more likely than men to develop right-sided colon cancers, colonoscopy is the preferred screening test in women. Currently, women are less likely to undergo colorectal cancer screening than men. Frank discussions addressing the fear or embarrassment of endoscopic screening are important in helping women overcome these barriers. Enhanced education of both practitioners and patients targeted to improve colorectal cancer screening adherence will improve early diagnosis and patient survival.

Promoter CpG island methylation markers in colorectal cancer: the road ahead

Despite increasing knowledge on the biology, detection and treatment of colorectal cancer (CRC), the disease is still a major health problem. Hypermethylation of promoter regions of genes has been studied extensively as a contributor in CRC carcinogenesis. In addition, it is the topic of many studies focusing on biomarkers for the early detection, prediction of prognosis and treatment outcome. Methylation markers may be preferred over current screening and test methods as they are stable and easy to detect. However, almost no methylation marker is currently being used in clinical practice, often due to a lack of sensitivity, specificity, or validation of the results. This review summarizes the current knowledge of hypermethylation biomarkers for CRC detection, progression and treatment outcome.

Analytical sensitivity and stability of DNA methylation testing in stool samples for colorectal cancer detection

BACKGROUND

Stool-based molecular tests hold large potential for improving colorectal cancer screening. Here, we investigated the analytical sensitivity of a DNA methylation assay on partial stool samples, and estimated the DNA degradation in stool over time. In addition, we explored the detection of DNA methylation in fecal immunochemical test (FIT) fluid.

MATERIALS AND METHODS

Partial stool samples of colonoscopy-negative individuals were homogenized with stool homogenization buffer, spiked with different numbers of HCT116 colon cancer cells and kept at room temperature for 0, 24, 48, 72 and 144 h before DNA isolation. Analytical sensitivity was determined by the lowest number of cells that yielded positive test results by DNA methylation or mutation analysis. DNA methylation in FIT fluid was measured in 11 CRC patients and 20 control subjects.

RESULTS

The analytical sensitivity for detecting DNA methylation was 3000 cells per gram stool, compared to 60000 cells per gram stool for detection of DNA mutations in the same stool samples. No degradation up to 72 h was noted when a conservation buffer was used. DNA methylation was detected in 4/11 CRC FIT samples and in none of the 20 control FIT samples.

CONCLUSIONS

Methylation based stool DNA testing showed a high analytical sensitivity for tumor DNA in partial stool samples, which was hardly influenced by DNA degradation over time, provided an adequate buffer was used. The feasibility of detecting DNA methylation in FIT fluid demonstrates the opportunity to combine testing for occult blood with DNA methylation in the same collection device.

Use of RNA isolated from feces as a promising tool for the early detection of colorectal cancer

Colorectal cancer is one of the most common forms of cancer worldwide. Early detection would allow patients to be treated surgically and halt the progression of the disease; however, the current methods of early detection are invasive (colonoscopy and sigmoidoscopy) or have low sensitivity (fecal occult blood test). The altered expression of genes in stool samples of patients with colorectal cancer can be determined by RT-PCR. This is a noninvasive and highly sensitive technique for colorectal cancer screening. According to information gathered in this review and our own experience, the use of fecal RNA to determine early alterations in gene expression due to malignancy appears to be a promising alternative to the current detection methods and owing to its low cost could be implemented in public health services.

Stool DNA screening for colorectal neoplasia: biological and technical basis for high detection rates

Colorectal cancer (CRC), the second most common cause of cancer-related mortality worldwide, is preventable with effective screening and removal of precursor lesions. Yet, screening efforts have been hampered by low participation rates and by performance limitations of the screening tools themselves. Stool DNA testing has emerged as a biologically rational and user-friendly strategy for the non-invasive detection of both CRC and critical precursor lesions. Unlike most conventional screening tools, stool DNA testing detects proximal and distal colorectal neoplasms equally well. Several key technical advances have led to increasingly accurate approaches for stool DNA testing including use of a DNA preservative buffer with stool collection, efficient target capture and amplification methods, broadly informative marker panels, and automated assay components. Based on recent studies, advanced multi-marker stool DNA tests including methylated markers, mutation markers and an assessment of faecal haemoglobin have been shown to detect CRC at sensitivities of 85% and higher and adenomas >1 cm at 60% and higher in a case-control environment. If the high accuracy of multi-marker stool tests is corroborated in multicentre screening studies on average-risk persons currently underway, then these stool tests could influence our CRC screening paradigm.This review discusses the biological basis, key technical advances, and recent clinical performance validation of stool DNA testing.

Novel molecular screening approaches in colorectal cancer

Traditional methods for colorectal cancer (CRC) screening have reduced rates of malignancy and death; however, low compliance and morbidities associated with invasive techniques have encouraged efforts for establishing equally effective, less invasive novel screening approaches. We review the current state of novel screening approaches in CRC to include CT colonography, fecal DNA, DNA methylation, micro-RNA, and protein and molecular markers.

The stool DNA test is more accurate than the plasma septin 9 test in detecting colorectal neoplasia

BACKGROUND & AIMS

Several noninvasive tests have been developed for colorectal cancer (CRC) screening. We compared the sensitivities of a multimarker test for stool DNA (sDNA) and a plasma test for methylated septin 9 (SEPT9) in identifying patients with large adenomas or CRC.

METHODS

We analyzed paired stool and plasma samples from 30 patients with CRC and 22 with large adenomas from Mayo Clinic archives. Stool (n = 46) and plasma (n = 49) samples from age- and sex-matched patients with normal colonoscopy results were used as controls. The sDNA test is an assay for methylated BMP3, NDRG4, vimentin, and TFPI2; mutant KRAS; the β-actin gene, and quantity of hemoglobin (by the porphyrin method). It was performed blindly at Exact Sciences (Madison, Wisconsin); the test for SEPT9 was performed at ARUP Laboratories (Salt Lake City, Utah). Results were considered positive based on the manufacturer's specificity cutoff values of 90% and 89%, respectively.

RESULTS

The sDNA test detected adenomas (median, 2 cm; range, 1-5 cm) with 82% sensitivity (95% confidence interval [CI], 60%-95%); SEPT9 had 14% sensitivity (95% CI, 3%-35%; P = .0001). The sDNA test identified patients with CRC with 87% sensitivity (95% CI, 69%-96%); SEPT9 had 60% sensitivity (95% CI, 41%-77%; P = .046). The sDNA test identified patients with stage I-III CRC with 91% sensitivity (95% CI, 71%-99%); SEPT9 had 50% sensitivity (95% CI, 28%-72%; P = .013); for stage IV CRC, sensitivity values were 75% (95% CI, 35%-97%) and 88% (95% CI, 47%-100%), respectively (P = .56). False positive rates were 7% for the sDNA test and 27% for SEPT9.

CONCLUSIONS

Based on analyses of paired samples, the sDNA test detects nonmetastatic CRC and large adenomas with significantly greater levels of sensitivity than the SEPT9 test. These findings might be used to modify approaches for CRC prevention and early detection.

Next-generation stool DNA test accurately detects colorectal cancer and large adenomas

BACKGROUND & AIMS

Technical advances have led to stool DNA (sDNA) tests that might accurately detect neoplasms on both sides of the colorectum. We assessed colorectal neoplasm detection by a next-generation sDNA test and effects of covariates on test performance.

METHODS

We performed a blinded, multicenter, case-control study using archived stool samples collected in preservative buffer from 252 patients with colorectal cancer (CRC), 133 with adenomas ≥ 1 cm, and 293 individuals with normal colonoscopy results (controls); two-thirds were randomly assigned to a training set and one-third to a test set. The sDNA test detects 4 methylated genes, a mutant form of KRAS, and the α-actin gene (as a reference value) using quantitative, allele-specific, real-time target and signal amplification; it also quantifies hemoglobin. We used a logistical model to analyze data.

RESULTS

The sDNA test identified 85% of patients with CRC and 54% of patients with adenomas ≥1 cm with 90% specificity. The test had a high rate of detection for all nonmetastatic stages of CRC (aggregate 87% detection rate for CRC stages I-III). Detection rates increased with adenoma size: 54% ≥ 1 cm, 63% >1 cm, 77% >2 cm, 86% >3 cm, and 92% >4 cm (P < .0001). Based on receiver operating characteristic analysis, the rate of CRC detection was slightly greater for the training than the test set (P = .04), whereas the rate of adenoma detection was comparable between sets. Sensitivities for detection of CRC and adenoma did not differ with lesion site.

CONCLUSIONS

Early-stage CRC and large adenomas can be detected throughout the colorectum and with high levels of accuracy by the sDNA test. Neoplasm size, but not anatomical site, affected detection rates. Further studies are needed to validate the findings in a larger population and optimize the sDNA test.

Detection of hypermethylated vimentin in urine of patients with colorectal cancer

We demonstrated previously that urine contains low-molecular-weight (LMW) (<300 bp), circulation-derived DNA that can be used to detect cancer-specific mutations if a tumor is present. The goal of this study was to develop an assay to detect the colorectal cancer (CRC)-associated, circulation-derived, epigenetic DNA marker hypermethylated vimentin gene (mVIM) in the urine of patients with CRC. An artificial 18-nucleotide DNA sequence was tagged at the 5' end of the primers of the first PCR cycle to increase the amplicon size, which was then integrated into the primers of the second PCR cycle. A quantitative MethyLight PCR-based assay targeting a 39-nucleotide template was developed and used to quantify mVIM in CRC tissues and matched urine samples. mVIM was detected in 75% of LMW urine DNA samples from patients with CRC (n = 20) and in 10% of urine samples of control subjects with no known neoplasia (n = 20); 12 of 17 LMW urine DNA samples (71%) but only 2 of 17 high-molecular-weight urine DNA samples (12%) from patients with mVIM-positive tissues contained detectable mVIM, suggesting that the mVIM detected in LMW urine DNA is derived from the circulation. The detection of mVIM in urine was significantly associated with CRC compared with controls (P < 0.0001, by Fisher's exact test). A potential urine test for CRC screening using epigenetic markers is discussed.

Patients with colorectal cancer are characterized by increased concentration of fecal hb-hp complex, myeloperoxidase, and secretory IgA

OBJECTIVES

The aim of our study was to evaluate the use of fecal hemoglobin-haptoglobin (Hb-Hp) complex, myeloperoxidase (MPO), and secretory IgA as potential diagnostic markers for the screening of colorectal cancer.

METHODS

Our study consisted of 190 participants (150 patients and 40 healthy individuals) aged 40 to 70 years who underwent complete colonoscopy. From each participant, a stool sample was collected 1 day before colonoscopy. The patients were instructed to collect another sample after the fourteenth postoperative day. No special diet was recommended.

RESULTS

In the control group, all fecal markers were within normal values in most participants. Colorectal tumors were accompanied by a highly significant increase in all markers. The median value of Hb-Hp complex was 23.22±10.02 (P<0.0001) whereas the median values of MPO and sIgA were 14936.43±9580.83 (P<0.0001) and 6503.38±2794.87 (P<0.0001), respectively. The sensitivity and specificity of Hb-Hp complex, MPO, and sIgA are 95.3% and 87.5%, 96% and 87%, and 90.8% and 85%, respectively. The difference of preoperative and postoperative values of the patients was statistically significant for all markers. After surgical intervention, the value of Hb-Hp complex was normalized in 133 of the 150 patients (88.7%). The postoperative values of MPO were within normal limits in 131 patients (87.3%), whereas those of secretory IgA were within normal limits in 103 of the 150 patients (68.5%).

CONCLUSION

Fecal Hb-Hp complex, MPO, and sIgA can effectively be used as screening tools for the early diagnosis of colorectal cancer, and for the postoperative follow-up of patients.

Review of biomarkers in colorectal cancer

AIM

Advances in molecular technology have resulted in the discovery of many putative biomarkers relevant to colorectal cancer (CRC).

METHOD

Literature searches were performed on PubMed and EMBASE using the words 'colorectal cancer', AND 'biomarkers OR markers'. Biomarkers that are either currently in clinical use or have potential clinical use were identified.

RESULTS

Most potential markers are in the discovery phase waiting to undergo clinical validation. Hypermethylation of the plasma septin-9 gene shows promise as a nonstool-based screening tool. Hypermethylation of the DYPD gene (encodes the enzyme dihydropyrimidine dehydrogenase) and variation of the uridine diphosphate-glucuronosyltransferase 1A (UGT1A1) gene have predictive value for side effects and the efficacy of 5-fluoruracil and irinotecan, respectively. Mismatch repair protein immunohistochemistry is able to predict response to 5-fluorouracil, and the KRAS (Kirsten rat sarcoma viral oncogene) and B-RAF (v-RAF murine sarcoma viral oncogene homolog B1) somatic gene mutation status can predict the response to anti-epidermal growth factor receptor therapy.

CONCLUSION

Recent advances indicate that the widespread use of biomarkers may herald the next major advance in the diagnosis and management of CRC.

In vivo measurement of Helicobacter pylori infection

Helicobacter pylori is a well-recognized gastroduodenal pathogen (National Institute of Health Consensus Conference, JAMA 272:65-9, 1994) and a class I carcinogen (International Agency for Research on Cancer, IARC Monograph on the Evaluation of Carcinogenic Risk to Humans 61:177-240, 1994) which successfully colonizes the harsh acidic environment of the stomach. H. pylori is the causative factor for peptic ulcer disease (PUD) and an independent risk factor for gastric adenocarcinoma development. Therefore, accurate detection of infection is crucial for devising proper eradication regimens and preventing the more severe GI complications.Detection of H. pylori in the gastric mucosa can be performed via (1) direct detection of the bacterium; culture, histology and polymerase chain reaction (PCR) or (2) indirect detection of its enzymatic products particularly urease as well as serum H. pylori-specific antibody responses, which can be detected by rapid urease test (RUT) and serology, respectively.The accuracy of these diagnostic tests is reported as follows: 98.1% for bacterial culture, 98.1% for histology, 94.3% for PCR, 96.2% for RUT, and 84.9% for serology (Ni et al, J Pediatr 136(6):823-7, 2000).

Age-related topographical metabolic signatures for the rat gastrointestinal contents

Symbiotic gut microbiota is essential for mammalian physiology and analyzing the metabolite compositions of gastrointestinal contents is vital for understanding the microbiome-host interactions. To understand the developmental dependence of the topographical metabolic signatures for the rat gastrointestinal contents, we systematically characterized the metabolite compositional variations of the contents in rat jejunum, ileum, cecum, and colon for two age-groups using (1)H NMR spectroscopy and multivariate analysis. Significant topographical metabolic variations were present for the jejunal, ileal, cecal, colonic contents, and feces, reflecting the absorption functions for each intestinal region and the gut microbiota therein. The concentrations of amino acids, lactate, creatine, choline, bile acids, uracil and urocanate decreased drastically from jejunal to ileal contents followed with steady decreases from cecal content to feces. Short-chain fatty acids (SCFAs) and arabinoxylan-related carbohydrates had highest levels in cecal content and feces, respectively. Such topographical metabolic signatures for the intestinal contents varied with animal age highlighted by the level changes for lactate, choline, taurine, amino acids, carbohydrates, keto-acids, and SCFAs. These findings provided essential information for the topographical metabolic variations in the gastrointestinal tract and demonstrated metabolic profiling as a useful approach for understanding host-microbiome interactions and functional status of the gastrointestinal regions.

DNA methylation of phosphatase and actin regulator 3 detects colorectal cancer in stool and complements FIT

Using a bioinformatics-based strategy, we set out to identify hypermethylated genes that could serve as biomarkers for early detection of colorectal cancer (CRC) in stool. In addition, the complementary value to a Fecal Immunochemical Test (FIT) was evaluated. Candidate genes were selected by applying cluster alignment and computational analysis of promoter regions to microarray-expression data of colorectal adenomas and carcinomas. DNA methylation was measured by quantitative methylation-specific PCR on 34 normal colon mucosa, 71 advanced adenoma, and 64 CRC tissues. The performance as biomarker was tested in whole stool samples from in total 193 subjects, including 19 with advanced adenoma and 66 with CRC. For a large proportion of these series, methylation data for GATA4 and OSMR were available for comparison. The complementary value to FIT was measured in stool subsamples from 92 subjects including 44 with advanced adenoma or CRC. Phosphatase and Actin Regulator 3 (PHACTR3) was identified as a novel hypermethylated gene showing more than 70-fold increased DNA methylation levels in advanced neoplasia compared with normal colon mucosa. In a stool training set, PHACTR3 methylation showed a sensitivity of 55% (95% CI: 33-75) for CRC and a specificity of 95% (95% CI: 87-98). In a stool validation set, sensitivity reached 66% (95% CI: 50-79) for CRC and 32% (95% CI: 14-57) for advanced adenomas at a specificity of 100% (95% CI: 86-100). Adding PHACTR3 methylation to FIT increased sensitivity for CRC up to 15%. PHACTR3 is a new hypermethylated gene in CRC with a good performance in stool DNA testing and has complementary value to FIT.

Differential expression of miR-144* as a novel fecal-based diagnostic marker for colorectal cancer

BACKGROUND

MicroRNAs (miRNA) are tiny, noncoding, small, endogenous RNAs that play major roles in neoplastic transformation and could therefore offer a better quantitative and noninvasive method for the diagnosis and prognosis of colorectal cancer (CRC) using feces. In the present study, we screened feces for 648 miRNAs and analyzed the role of miR-144* as a potential CRC diagnostic marker.

METHODS

Fecal miRNA expression was profiled with RT-pre-amplification-qPCR, and the stability was determined using both endogenous and exogenous miRNA by RT-qPCR. ROC analysis was performed to enhance the diagnosing power of the CRC patients' fecal specimens.

RESULTS

We detected 39% of all the miRNAs screened in feces. Endogenous miRNAs are more stable over time and temperature, while exogenous miRNAs degraded rapidly. miR-144* was overexpressed in feces, suggesting that it could be a potent candidate diagnostic marker for CRC detection, with a sensitivity of 74% and a specificity of 87% (n = 75, p < 0.0001). Moreover, RT-qPCR analysis showed that miR-144* was also overexpressed in paired CRC tissues, thus suggesting its possible utilization as a diagnostic marker.

CONCLUSIONS

We demonstrated that miRNAs are stable in the fecal microenvironment, and that, among them, miR-144* represents a novel fecal-based diagnostic marker for CRC screening. Nevertheless, our data need to be validated in a large cohort of subjects.

Fecal molecular markers for colorectal cancer screening

Despite multiple screening techniques, including colonoscopy, flexible sigmoidoscopy, radiological imaging, and fecal occult blood testing, colorectal cancer remains a leading cause of death. As these techniques improve, their sensitivity to detect malignant lesions is increasing; however, detection of precursor lesions remains problematic and has generated a lack of general acceptance for their widespread usage. Early detection by an accurate, noninvasive, cost-effective, simple-to-use screening technique is central to decreasing the incidence and mortality of this disease. Recent advances in the development of molecular markers in faecal specimens are encouraging for its use as a screening tool. Genetic mutations and epigenetic alterations that result from the carcinogenetic process can be detected by coprocytobiology in the colonocytes exfoliated from the lesion into the fecal matter. These markers have shown promising sensitivity and specificity in the detection of both malignant and premalignant lesions and are gaining popularity as a noninvasive technique that is representative of the entire colon. In this paper, we summarize the genetic and epigenetic fecal molecular markers that have been identified as potential targets in the screening of colorectal cancer.

Screening for colorectal cancer: established and emerging modalities

It has been estimated that >95% of cases of colorectal cancer (CRC) would benefit from curative surgery if diagnosis was made at an early or premalignant polyp stage of disease. Over the past 10 years, most developed nation states have implemented mass population screening programs, which are typically targeted at the older (at-risk) age group (>50-60 years old). Conventional screening largely relies on periodic patient-centric investigation, particularly involving colonoscopy and flexible sigmoidoscopy, or else on the fecal occult blood test. These methods are compromised by either low cost-effectiveness or limited diagnostic accuracy. Advances in the development of diagnostic molecular markers for CRC have yielded an expanding list of potential new screening modalities based on investigations of patient stool (for colonocyte DNA mutations, epigenetic changes or microRNA expression) or blood specimens (for plasma DNA mutations, epigenetic changes, heteroplasmic mitochondrial DNA mutations, leukocyte transcriptome profile, plasma microRNA expression or protein and autoantibody expression). In this Review, we present a critical evaluation of the performance data and relative merits of these various new potential methods. None of these molecular diagnostic methods have yet been evaluated beyond the proof-of-principle and pilot-scale study stage and it could be some years before they replace existing methods for population screening in CRC.

Molecular tests for colorectal cancer screening

Detecting and removing high-risk adenomas and early colorectal cancer (CRC) can reduce mortality of this disease. The noninvasive fecal occult blood test (FOBT; guaiac-based or immunochemical) is widely used in screening programs and although effective, it leaves room for improvement in terms of test accuracy. Molecular tests are expected to be more sensitive, specific and informative than current detection tests, and are promising future tools for CRC screening. This review provides an overview of the performances of DNA, RNA, and protein markers for CRC detection in stool and blood. Most emphasis currently is on DNA and protein markers. Among DNA markers there is trend to move away from mutation markers in favor of methylation markers. The recent boost in proteomics research leads to many new candidate protein markers. Usually in small series, some markers show better performance than the present FOBT. Evaluation in large well-controlled randomized trials is the next step needed to take molecular markers for CRC screening to the next level and warrant implementation in a screening setting.

Colorectal cancer screening: update for 2011

Colorectal cancer is the third most common cancer in the United States. Although mortality and incidence rates are declining in the United States, colorectal cancer screening remains underused. In addition, recent data suggest that colonoscopy, which is often considered the gold standard for colorectal cancer screening, is less protective for right-sided tumors, which are more likely to be flat or depressed and are more affected by an inadequate bowel preparation. Imaging technologies such as chromoendoscopy and narrow band imaging have been developed to improve delineation of suspicious lesions during colonoscopy. In addition, other new modalities such as computed tomography colonography (CTC), capsule endoscopy, fecal immunochemical tests, and fecal DNA tests may offer less invasive screening options for patients who decline colonoscopy.

Screening for colorectal carcinoma

Colorectal carcinoma is the second most common cause of death in Canada. Because there is a precursor lesion (that is, the polyp), screening is critically important to prevent the disease through polyp removal-and failing that, to detect colorectal carcinoma at an early stage, when it can be cured. Several screening modalities are available, but colonoscopy is considered the best. People should avail themselves of such examinations, and physicians should encourage them to do so.

Screening options and recommendations for colorectal cancer

Screening reduces the burden of disease from colorectal cancer through early detection of cancerous lesions and removal of precancerous polyps. The ideal colorectal cancer screening modality should be cost-effective, increase life-years gained, permit long intervals between tests with high patient compliance and low risk to the patient. Although no single colorectal cancer screening method is perfect, several options exist. Government agencies and medical societies have published screening recommendations with differing guidelines; yet, despite the lack of a consistent standard, it is clear that colorectal cancer screening is cost-effective. In this review, the authors address several options for screening, identify risks and benefits, and present methods to risk stratify patients. A thorough discussion with the patient about potential benefits and harms is critical before initiating any screening regimen.

Potential of soluble CD26 as a serum marker for colorectal cancer detection

Colorectal cancer is characterized by a low survival rate even though the basis for colon cancer development, which involves the evolution of adenomas to carcinoma, is known. Moreover, the mortality rates continue to rise in economically transitioning countries although there is the opportunity to intervene in the natural history of the adenoma–cancer sequence through risk factors, screening, and treatment. Screening in particular accounted for most of the decline in colorectal cancer mortality achieved in the USA during the period 1975-2000. Patients show a better prognosis when the neoplasm is diagnosed early. Among the variety of screening strategies, the methods range from invasive and costly procedures such as colonoscopy to more low-cost and non-invasive tests such as the fecal occult blood test (guaiac and immunochemical). As a non-invasive biological serum marker would be of great benefit because of the performance of the test, several biomarkers, including cytologic assays, DNA and mRNA, and soluble proteins, have been studied. We found that the soluble CD26 (sCD26) concentration is diminished in serum of colorectal cancer patients compared to healthy donors, suggesting the potential utility of a sCD26 immunochemical detection test for early diagnosis. sCD26 originates from plasma membrane CD26 lacking its transmembrane and cytoplasmic domains. Some 90%–95% of sCD26 has been associated with serum dipeptidyl peptidase IV (DPP-IV) activity. DPP-IV, assigned to the CD26 cluster, is a pleiotropic enzyme expressed mainly on epithelial cells and lymphocytes. Our studies intended to validate this test for population screening to detect colorectal cancer and advanced adenomas are reviewed here.

Detection of methylated tissue factor pathway inhibitor 2 and human long DNA in fecal samples of patients with colorectal cancer in China

BACKGROUND

To investigate the feasibility of detecting methylated tissue factor pathway inhibitor (TFPI2) and quantifying human long DNA with fluorescent quantitative Alu PCR in fecal DNA as a non-invasive screening tool for colorectal cancer (CRC).

MATERIALS AND METHODS

Methylation-specific PCR (MSP) was performed to analyze TFPI2 gene promoter methylation status in a blinded fashion in stool samples taken from 30 endoscopically diagnosed healthy controls, 20 patients with adenomas, and 60 patients with colorectal cancer. Real-time Alu PCR was used to quantify human long DNA.

RESULTS

The specificity of fecal TFPI2 MSP assay and long DNA assay was 100% and 83.3%, respectively. The sensitivity of fecal TFPI2 MSP assay and long DNA assay was 68.3% and 53.3%, respectively. The sensitivity of fecal DNA assay (either marker being positive) was 86.7%, which was high for CRC.

CONCLUSIONS

Our results have demonstrated the feasibility of using TFPI2 methylation and quantify human long DNA with fluorescent quantitative Alu PCR in fecal samples as a new noninvasive test for CRC.

Use of multiple reaction monitoring for multiplex analysis of colorectal cancer-associated proteins in human feces

Colorectal cancer (CRC) is the second most common cause of cancer-related deaths worldwide with an annual incidence of almost a million cases and an annual mortality around 500,000. The fecal occult blood test is currently the first line method for CRC screening, but has unacceptably low sensitivity and specificity. Improved screening tests are therefore urgently required for early-stage CRC screening when therapy is most likely to be effective. We describe a discovery-based proteomics hypothesis using orthogonal multi-dimensional fractionation (1-D SDS-PAGE, RP-HPLC, size exclusion chromatography) to mine deep into the fecal proteome for the initial discovery process, which generated a library containing 108 human fecal proteins with the associated peptide and MS/MS data. These data were then used to develop and optimize a multiplex multiple reaction monitoring assay for 40 non-redundant human proteins present in the feces. To show proof of principal for clinical analysis, multiplex screening of these 40 proteins was carried out on fecal samples from eight CRC patient and seven normal volunteers. We identified 24 proteins consistently found in all samples and nine proteins found only in the CRC patients, showing the potential of this approach for the analysis of potential CRC biomarkers. Absolute quantitation using C-terminal isotopically labeled synthetic peptides corresponding to hemoglobin and carcinoembryonic antigen 5 was also performed.

A simplified, non-invasive fecal-based DNA integrity assay and iFOBT for colorectal cancer detection

PURPOSE

Neoplasia cells exfoliated from colorectal epithelium have dysfunctional apoptotic mechanisms, thus it is possible to identify high-molecular weight DNA fragments in feces. This prospective single-center study was performed to evaluate the sensitivity and specificity of fecal-based DNA integrity versus immunological fecal occult blood test (iFOBT) and calprotectin for colorectal cancer (CRC) and adenoma detection.

METHODS

Feces were collected from 204 subjects and DNA integrity was quantified by quantitative-denaturing high performance liquid chromatography (QdHPLC). Calprotectin and iFOBT were assessed using commercial kits. The diagnostic performance was calculated by receiver operating characteristic (ROC) curves analysis.

RESULTS

A total of 192 fecal specimens were analyzed and 12 samples were excluded due to DNA degradation. We found long DNA (L-DNA) occurrence in feces with a sensitivity of 86% (n = 24/28) and a specificity of 81% for CRC detection. To minimize false-positive cases of the developed test, area under the curve of ROC was evaluated such that the specificity was increased to 92% with decreased sensitivity to 79%, p = 0.0001 for CRC detection. iFOBT was positive in 51% (n = 14/27) while calprotectin was positive in 75% (n = 18/27). The combination of iFOBT and L-DNA identified a greater number of CRC cases with a sensitivity of 89% and a specificity of 95%, p < 0.001. The combination also improved the sensitivity of polyps, particularly high-grade dysplasia and advanced adenoma (33%, p = 0.0015) as opposed to a single evaluation assay (17-21%).

CONCLUSIONS

This study illustrates the usefulness of fecal DNA integrity assay by QdHPLC as a non-invasive, easy-to-perform, and reproducible method with a high level of sensitivity in detecting individuals with colorectal neoplasia. Combination of iFOBT and L-DNA improves the sensitivity for CRC and adenoma detection.

Fecal DNA for noninvasive diagnosis of colorectal cancer in immunochemical fecal occult blood test-positive individuals

BACKGROUND

We aimed to define the potential of the fecal DNA assay as an alternative or in addition to the currently used immunochemical fecal occult blood test (iFOBT) for the early diagnosis of colorectal cancer.

METHODS

A total of 560 individuals aged 50 to 69 years with a positive iFOBT were recruited from an Italian FOBT regional screening program. Twenty-six were diagnosed with adenocarcinoma, 264 with high-risk adenoma, and 54 with low-risk adenoma, whereas 216 subjects did not have premalignant or malignant lesions. Fecal DNA integrity was analyzed blindly by the fluorescence long DNA (FL-DNA) test.

RESULTS

iFOBT and FL-DNA were largely independent variables (rs = 0.036, P = 0.42), with values ranging from 101 to 5,826 ng/mL and from 0 to 515 ng, respectively. Median values of both variables were significantly higher in cancer patients than in patients with noncancerous lesions or in healthy individuals. Moreover, iFOBT and FL-DNA values were individually associated with a number of pathologic parameters. Sequential use of the diagnostic iFOBT and FL-DNA methods showed that fecal DNA provided more accurate diagnostic information and was able to identify subgroups at different risk of cancer in iFOBT-positive individuals.

CONCLUSIONS

A combined approach based on FL-DNA and iFOBT evaluation could help to better identify colorectal cancers and to determine a patient's risk of harboring a preneoplastic or neoplastic lesion. Further evaluation in a screening setting is needed to confirm this hypothesis.

IMPACT

Fecal DNA could be a useful tool to better predict cancer risk in FOBT-positive individuals.

Fecal Tests: From Blood to Molecular Markers

Detection of molecular markers for colorectal neoplasia in feces has the potential to improve performance of simple noninvasive screening tests for colorectal cancer. Most research has explored the value of DNA-based, RNA-based, and protein-based markers. In all cases there has been a trend to move from a single marker to a panel of markers to improve sensitivity. Unfortunately, no type of molecular marker has proved specific for neoplasia. DNA tests have been improved by combining mutation detection with assessment of DNA integrity plus epigenetic markers of neoplasia. RNA-based approaches are just beginning to explore the full power of transcriptomics. So far, no protein-based fecal test has proved better than fecal immunochemical tests for hemoglobin. Finally, no marker or panel of markers has yet been developed to the point where it has been evaluated in large unbiased population studies to assess performance across all stages of neoplasia and in all practical environments.

A simplified, non-invasive fecal-based DNA integrity assay and iFOBT for colorectal cancer detection

PURPOSE

Neoplasia cells exfoliated from colorectal epithelium have dysfunctional apoptotic mechanisms, thus it is possible to identify high-molecular weight DNA fragments in feces. This prospective single-center study was performed to evaluate the sensitivity and specificity of fecal-based DNA integrity versus immunological fecal occult blood test (iFOBT) and calprotectin for colorectal cancer (CRC) and adenoma detection.

METHODS

Feces were collected from 204 subjects and DNA integrity was quantified by quantitative-denaturing high performance liquid chromatography (QdHPLC). Calprotectin and iFOBT were assessed using commercial kits. The diagnostic performance was calculated by receiver operating characteristic (ROC) curves analysis.

RESULTS

A total of 192 fecal specimens were analyzed and 12 samples were excluded due to DNA degradation. We found long DNA (L-DNA) occurrence in feces with a sensitivity of 86% (n = 24/28) and a specificity of 81% for CRC detection. To minimize false-positive cases of the developed test, area under the curve of ROC was evaluated such that the specificity was increased to 92% with decreased sensitivity to 79%, p = 0.0001 for CRC detection. iFOBT was positive in 51% (n = 14/27) while calprotectin was positive in 75% (n = 18/27). The combination of iFOBT and L-DNA identified a greater number of CRC cases with a sensitivity of 89% and a specificity of 95%, p < 0.001. The combination also improved the sensitivity of polyps, particularly high-grade dysplasia and advanced adenoma (33%, p = 0.0015) as opposed to a single evaluation assay (17-21%).

CONCLUSIONS

This study illustrates the usefulness of fecal DNA integrity assay by QdHPLC as a non-invasive, easy-to-perform, and reproducible method with a high level of sensitivity in detecting individuals with colorectal neoplasia. Combination of iFOBT and L-DNA improves the sensitivity for CRC and adenoma detection.