A simplified, noninvasive stool DNA test for colorectal cancer detection

Detection of promoter hypermethylation of Wnt antagonist genes in fecal samples for diagnosis of early colorectal cancer

AIM: To investigate the feasibility of detecting aberrantly hypermethylated Wnt-antagonist gene promoters (SFRP2 and WIF-1) in fecal DNA as non-invasive biomarkers for early colorectal cancer (CRC).

METHODS: The methylation-specific polymerase chain reaction assay was performed to blindly analyze the methylation status of SFRP2 and WIF-1 gene promoters in fecal samples from 48 subjects with CRC, 35 with adenomas, 32 with hyperplastic polyps and 30 endoscopically normal subjects. Additionally, we compared the diagnostic efficiency of measuring the hypermethylated SFRP2 and WIF-1 genes in the feces to the fecal occult blood test (FOBT) for the early detection of CRC.

RESULTS: Hypermethylated SFRP2 was detected in the feces of 56.3% (27/48) of CRC cases, 51.4% (18/35) of adenoma cases and 12.5% (4/32) of patients with hyperplastic polyps. The hypermethylation of WIF-1 was detected in 60.4% (29/48), 45.7% (16/35) and 18.7% (6/32) of fecal samples from CRC, adenoma and hyperplastic polyp patients, respectively. At least one hypermethylated gene was detected in 81.3% (39/48) of CRC and 65.7% (23/35) of adenoma samples. In contrast, only a hypermethylated WIF-1 gene was detected in one case of normal fecal samples. Moreover, no significant associations were observed between SFPR2 and WIF-1 hypermethylation and clinicopathological features. Additionally, 81.8% of CRC cases diagnosed as Dukes A stage or advanced adenomas had at least one hypermethylated gene detected, while the detection rate with the FOBT was only 31.8% (P < 0.001).

CONCLUSION: Hypermethylated SFRP2 and WIF-1 genes in fecal DNA are novel and promising molecular biomarkers that have great diagnostic potential for early CRC.

Advances in epigenetic biomarker research in colorectal cancer

Colorectal cancer (CRC) causes approximately 600000 deaths annually and is the third leading cause of cancer mortality worldwide. Despite significant advancements in treatment options, CRC patient survival is still poor owing to a lack of effective tools for early diagnosis and a limited capacity for optimal therapeutic decision making. Since there exists a need to find new biomarkers to improve diagnosis of CRC, the research on epigenetic biomarkers for molecular diagnostics encourages the translation of this field from the bench to clinical practice. Epigenetic alterations are thought to hold great promise as tumor biomarkers. In this review, we will primarily focus on recent advances in the study of epigenetic biomarkers for colorectal cancer and discuss epigenetic biomarkers, including DNA methylation, microRNA expression and histone modification, in cancer tissue, stool, plasma, serum, cell lines and xenografts. These studies have improved the chances that epigenetic biomarkers will find a place in the clinical practices of screening, early diagnosis, prognosis, therapy choice and recurrence surveillance for CRC patients. However, these studies have typically been small in size, and evaluation at a larger scale of well-controlled randomized clinical trials is the next step that is necessary to increase the quality of epigenetic biomarkers and ensure their widespread clinical use.

Multitarget stool DNA testing for colorectal-cancer screening

BACKGROUND

An accurate, noninvasive test could improve the effectiveness of colorectal-cancer screening.

METHODS

We compared a noninvasive, multitarget stool DNA test with a fecal immunochemical test (FIT) in persons at average risk for colorectal cancer. The DNA test includes quantitative molecular assays for KRAS mutations, aberrant NDRG4 and BMP3 methylation, and β-actin, plus a hemoglobin immunoassay. Results were generated with the use of a logistic-regression algorithm, with values of 183 or more considered to be positive. FIT values of more than 100 ng of hemoglobin per milliliter of buffer were considered to be positive. Tests were processed independently of colonoscopic findings.

RESULTS

Of the 9989 participants who could be evaluated, 65 (0.7%) had colorectal cancer and 757 (7.6%) had advanced precancerous lesions (advanced adenomas or sessile serrated polyps measuring ≥1 cm in the greatest dimension) on colonoscopy. The sensitivity for detecting colorectal cancer was 92.3% with DNA testing and 73.8% with FIT (P=0.002). The sensitivity for detecting advanced precancerous lesions was 42.4% with DNA testing and 23.8% with FIT (P<0.001). The rate of detection of polyps with high-grade dysplasia was 69.2% with DNA testing and 46.2% with FIT (P=0.004); the rates of detection of serrated sessile polyps measuring 1 cm or more were 42.4% and 5.1%, respectively (P<0.001). Specificities with DNA testing and FIT were 86.6% and 94.9%, respectively, among participants with nonadvanced or negative findings (P<0.001) and 89.8% and 96.4%, respectively, among those with negative results on colonoscopy (P<0.001). The numbers of persons who would need to be screened to detect one cancer were 154 with colonoscopy, 166 with DNA testing, and 208 with FIT.

CONCLUSIONS

In asymptomatic persons at average risk for colorectal cancer, multitarget stool DNA testing detected significantly more cancers than did FIT but had more false positive results. (Funded by Exact Sciences; ClinicalTrials.gov number, NCT01397747.).

Validation of methylation-sensitive high-resolution melting (MS-HRM) for the detection of stool DNA methylation in colorectal neoplasms

BACKGROUND

Methylation-sensitive high-resolution melting (MS-HRM) is a new technique for assaying DNA methylation, but its feasibility for assaying stool in patients with colorectal cancer (CRC) is unknown.

METHODS

First, the MS-HRM and methylation-specific PCR (MSP) detection limits were tested. Second, the methylation statuses of SFRP2 and VIM were analyzed in stool samples by MS-HRM, and in matching tumor and normal colon tissues via bisulfite sequencing PCR (BSP). Third, a case-control study evaluated the diagnostic sensitivity and specificity of MS-HRM relative to results obtained with MSP and the fecal immunochemical test (FIT). Finally, the linearity and reproducibility of MS-HRM were assessed.

RESULTS

The detection limits of MS-HRM and MSP were 1% and 5%, respectively. The diagnostic sensitivities of MS-HRM (87.3%, 55/63) in stool and BSP in matching tumor tissue (92.1%, 58/63) were highly consistent (κ=0.744). The MS-HRM assay detected 92.5% (37/40) methylation in CRCs, 94.4% (34/36) in advanced adenomas, and 8.8% (5/57) in normal controls. The results of MS-HRM analysis were stable and reliable and showed fairly good linearity for both SFRP2 (P<0.001, R(2)=0.957) and VIM (P<0.001, R(2)=0.954).

CONCLUSIONS

MS-HRM shows potential for CRC screening.

Genetic and epigenetic biomarkers for diagnosis, prognosis and treatment of colorectal cancer

Colorectal cancer (CRC) is one of the most common cancer worldwide and results from the accumulation of mutations and epimutations in colonic mucosa cells ultimately leading to cell proliferation and metastasis. Unfortunately, CRC prognosis is still poor and the search of novel diagnostic and prognostic biomarkers is highly desired to prevent CRC-related deaths. The present article aims to summarize the most recent findings concerning the use of either genetic or epigenetic (mainly related to DNA methylation) biomarkers for CRC diagnosis, prognosis, and response to treatment. Recent large-scale DNA methylation studies suggest that CRC can be divided into several subtypes according to the frequency of DNA methylation and those of mutations in key CRC genes, and that this is reflected by different prognostic outcomes. Increasing evidence suggests that the analysis of DNA methylation in blood or fecal specimens could represent a valuable non-invasive diagnostic tool for CRC. Moreover, a broad spectrum of studies indicates that the inter-individual response to chemotherapeutic treatments depends on both epigenetic modifications and genetic mutations occurring in colorectal cancer cells, thereby opening the way for a personalized medicine. Overall, combining genetic and epigenetic data might represent the most promising tool for a proper diagnostic, prognostic and therapeutic approach.

Comparison of CpG island methylator phenotype (CIMP) frequency in colon cancer using different probe- and gene-specific scoring alternatives on recommended multi-gene panels

Background

In colorectal cancer a distinct subgroup of tumours demonstrate the CpG island methylator phenotype (CIMP). However, a consensus of how to score CIMP is not reached, and variation in definition may influence the reported CIMP prevalence in tumours. Thus, we sought to compare currently suggested definitions and cut-offs for methylation markers and how they influence CIMP classification in colon cancer.

Methods

Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), with subsequent fragment analysis, was used to investigate methylation of tumour samples. In total, 31 CpG sites, located in 8 different genes (RUNX3, MLH1, NEUROG1, CDKN2A, IGF2, CRABP1, SOCS1 and CACNA1G) were investigated in 64 distinct colon cancers and 2 colon cancer cell lines. The Ogino gene panel includes all 8 genes, in addition to the Weisenberger panel of which only 5 of the 8 genes included were investigated. In total, 18 alternative combinations of scoring of CIMP positivity on probe-, gene-, and panel-level were analysed and compared.

Results

For 47 samples (71%), the CIMP status was constant and independent of criteria used for scoring; 34 samples were constantly scored as CIMP negative, and 13 (20%) consistently scored as CIMP positive. Only four of 31 probes (13%) investigated showed no difference in the numbers of positive samples using the different cut-offs. Within the panels a trend was observed that increasing the gene-level stringency resulted in a larger difference in CIMP positive samples than increasing the probe-level stringency. A significant difference between positive samples using ‘the most stringent’ as compared to ‘the least stringent’ criteria (20% vs 46%, respectively; p<0.005) was demonstrated.

Conclusions

A statistical significant variation in the frequency of CIMP depending on the cut-offs and genes included in a panel was found, with twice as many positives samples by least compared to most stringent definition used.

Molecular alterations and biomarkers in colorectal cancer

The promise of precision medicine is now a clinical reality. Advances in our understanding of the molecular genetics of colorectal cancer (CRC) are leading to the development of a variety of biomarkers that are being used as early detection markers, prognostic markers, and markers for predicting treatment responses. This is no more evident than in the recent advances in testing CRCs for specific molecular alterations in order to guide treatment with the monoclonal antibody therapies cetuximab and panitumumab, which target the epidermal growth factor receptor. In this review, we update a prior review published in 2010 and describe our current understanding of the molecular pathogenesis of CRC and how these alterations relate to emerging biomarkers for early detection and risk stratification (diagnostic markers), prognosis (prognostic markers), and the prediction of treatment responses (predictive markers).

Economic evaluation of colorectal cancer (CRC) screening

Because of its incidence and mortality colorectal cancer represents a serious public health issue in industrial countries. In order to reduce its social impact a number of screening strategies have been implemented, which allow an early diagnosis and treatment. These basically include faecal tests and studies that directly explore the colon and rectum. No strategy, whether alone or combined, has proven definitively more effective than the rest, but any such strategy is better than no screening at all. Selecting the most efficient strategy for inclusion in a population-wide program is an uncertain choice. Here we review the evidence available on the various economic evaluations, and conclude that no single method has been clearly identified as most cost-effective; further research in this setting is needed once common economic evaluation standards are established in order to alleviate the methodological heterogeneity prevailing in study results.

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.

Accuracy of early detection of colorectal tumours using stool methylation markers: A meta-analysis

AIM: To evaluate the accuracy of methylation of genes in stool samples for diagnosing colorectal tumours.

METHODS: Electronic databases including PubMed, Web of Science, Chinese Journal Full Text Database and Wanfang Journals Full-text Database were searched to find relevant original articles about methylated genes used in diagnosing colorectal tumours. Quality assessment of diagnostic accuracy studies items were used to evaluate the quality of the included articles, and the Meta-disc 1.4 and SPSS 13.0 software programs were used for data analysis.

RESULTS: Thirty-four articles met the inclusion criteria, and 4151 patients were included. Pooled diagnostic performances of SFRP2 methylation for colorectal cancer (CRC) provided the following results: the sensitivity was 79% (95%CI: 75%-82%), the specificity was 93% (95%CI: 90%-96%), the diagnostic odds ratio (DOR) was 47.57 (95%CI: 20.08-112.72), and the area under the curve was 0.9565. Additionally, the results of accuracy of SFRP2 methylation for detecting colorectal adenomas were as follows: the sensitivity was 43% (95%CI: 38%-49%), the specificity was 94% (95%CI: 91%-97%), the DOR was 11.06 (95%CI: 5.77-21.18), and the area under the curve was 0.9563.

CONCLUSION: Stool-based DNA testing may be useful for non-invasively diagnosing colorectal tumours, and SFRP2 methylation is a promising marker that has great potential in early CRC diagnosis.

Detection of fecal DNA methylation for colorectal neoplasia screening: A meta-analysis

AIM: To systemically evaluate the feasibility of using methylated genes as biomarkers for the detection of colorectal neoplasia.

METHODS: We searched PubMed, the Web of Science and On-line Visual Display Unit Interrogation of Data Bases (OVID) with the key words "colorectal cancer/colorectal adenoma/colorectal polyps", "methylation", "stool/fecal DNA" for studies that used hypermethylated genes as biomarkers for the detection of colorectal cancer (CRC) or adenomas. This meta-analysis used the sensitivity, specificity and 95% confidence intervals (95%CI) as effect measurements, and the Stata statistical software (version 11.0) was used to perform statistical analyses.

RESULTS: A total of 24 studies including 3555 patients were selected into the final analysis. The sensitivity and specificity of detecting single methylated gene in fecal DNA for the detection of colorectal neoplasia (CRC and adenomas) were 0.58 (95%CI: 0.51-0.66) and 0.93 (95%CI: 0.89-0.96), respectively. The sensitivity and specificity of detecting multiple methylated genes in fecal DNA for the detection of colorectal neoplasia were 0.79 (95%CI: 0.67-0.81) and 0.88 (95%CI: 0.86-0.91), respectively.

CONCLUSION: Analysis of stool DNA methylation has a reasonable sensitivity and specificity for the detection of CRC, and may provide a promising and noninvasive screening method for colorectal cancer. Combined detection of multiple methylated genes in fecal DNA is superior to the single gene detection method for colorectal neoplasia screening.

Functional epigenetic approach identifies frequently methylated genes in Ewing sarcoma

Using a candidate gene approach we recently identified frequent methylation of the RASSF2 gene associated with poor overall survival in Ewing sarcoma (ES). To identify effective biomarkers in ES on a genome-wide scale, we used a functionally proven epigenetic approach, in which gene expression was induced in ES cell lines by treatment with a demethylating agent followed by hybridization onto high density gene expression microarrays. After following a strict selection criterion, 34 genes were selected for expression and methylation analysis in ES cell lines and primary ES. Eight genes (CTHRC1, DNAJA4, ECHDC2, NEFH, NPTX2, PHF11, RARRES2, TSGA14) showed methylation frequencies of>20% in ES tumors (range 24-71%), these genes were expressed in human bone marrow derived mesenchymal stem cells (hBMSC) and hypermethylation was associated with transcriptional silencing. Methylation of NPTX2 or PHF11 was associated with poorer prognosis in ES. In addition, six of the above genes also showed methylation frequency of>20% (range 36-50%) in osteosarcomas. Identification of these genes may provide insights into bone cancer tumorigenesis and development of epigenetic biomarkers for prognosis and detection of these rare tumor types.

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.

Stool DNA testing for the detection of colorectal neoplasia in patients with inflammatory bowel disease

BACKGROUND

Current approaches to the detection of colorectal neoplasia associated with inflammatory bowel disease (IBD-CRN) are suboptimal.

AIM

To test the feasibility of using stool assay of exfoliated DNA markers to detect IBD-CRN.

METHODS

This investigation comprised tissue and stool studies. In the tissue study, gene sequencing and methylation assays were performed on candidate genes using tissue DNA from 25 IBD-CRNs and from 25 IBD mucosae without CRN. Mutations on p53, APC, KRAS, BRAF or PIK3CA genes were insufficiently informative, but several aberrantly methylated genes were highly discriminant. In the stool study, we evaluated candidate methylated genes (vimentin, EYA4, BMP3, NDRG4) in a prospective blinded study on buffered stools from 19 cases with known IBD-CRN and 35 age- and sex-matched IBD controls without CRN. From stool-extracted DNA, target genes were assayed using quantitative allele-specific real-time target and signal amplification method.

RESULTS

IBD-CRN cases included 17 with ulcerative colitis (UC) and two with Crohn's disease (CD); nine had cancer and 10 had dysplasia. Controls included 25 with UC and 10 with CD. Individually, BMP3, vimentin, EYA4 and NDRG4 markers showed high discrimination in stools with respective areas under the ROC curve of 0.91, 0.91, 0.85 and 0.84 for total IBD-CRN and of 0.97, 0.97, 0.95 and 0.85 for cancer. At 89% specificity, the combination of BMP3 and mNDRG4 detected 9/9 (100%) of CRC and 80% of dysplasia, 4/4 (100%) of high grade and 4/6 (67%) of low grade.

CONCLUSION

These findings demonstrate the feasibility of stool DNA testing for non-invasive detection of colorectal neoplasia associated with inflammatory bowel disease.

Detection of hypermethylated spastic paraplegia-20 in stool samples of patients with colorectal cancer

BACKGROUND

Analysis of aberrant hypermethylation in stool DNA might provide a novel strategy for noninvasive detection of colorectal cancer.

AIMS

To explore the feasibility of detecting hypermethylation in Spastic paraplegia-20 promoter as a stool-based DNA marker for detection of colorectal cancer.

METHODS

We collected 96 tissue and stool samples from patients with colorectal cancer and 30 stool samples healthy individuals.

RESULTS

Hypermethylated Spastic paraplegia-20 occurs in 85.4% (82/96) of patients with colorectal cancer in the tissue samples. In the stool samples, the results indicate 80.2% (77/96) sensitivity and 100% (30/30) specificity of the test for detecting colorectal cancer by using the stool samples as a noninvasive method.

CONCLUSIONS

The study reveals that hypermethylation in Spastic paraplegia-20 promoter is a highly specific and sensitive biomarker for screening colorectal cancer in stool samples as a noninvasive method.

Epigenetic biomarkers in colorectal cancer diagnostics

Colorectal cancer (CRC) is a significant health burden worldwide. Despite advancements in treatment options, improvements in CRC patient survival have been limited owing to lack of early detection and limited capacity for optimal therapeutic decision-making. Biomarkers to improve CRC diagnosis, prognosis and prediction of treatment response therefore represent opportunities to improve patient outcome. In addition to genetic alterations and genomic instability, it is now clear that epigenetic alterations play dramatic roles in driving tumor onset and progression in CRC. A recent surge in investigation of epigenetic biomarkers including DNA methylation, miRNA expression and histone modifications has demonstrated that these alterations may be enticing translational biomarker candidates in CRC. In particular, methylation kits have already been incorporated into clinical practice for a handful of cancers, including CRC. This review will aim to summarize the established and emerging roles of epigenetic modifications in CRC detection, prognostication and prediction of treatment response.

DNA methylation biomarkers in cancer: progress towards clinical implementation

Altered DNA methylation is ubiquitous in human cancers and specific methylation changes are often correlated with clinical features. DNA methylation biomarkers, which use those specific methylation changes, provide a range of opportunities for early detection, diagnosis, prognosis, therapeutic stratification and post-therapeutic monitoring. Here we review current approaches to developing and applying DNA methylation biomarkers in cancer therapy. We discuss the obstacles that have so far limited the routine use of DNA methylation biomarkers in clinical settings and describe ways in which these obstacles can be overcome. Finally, we summarize the current state of clinical implementation for some of the most widely studied and well-validated DNA methylation biomarkers, including SEPT9, VIM, SHOX2, PITX2 and MGMT.

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.

Advances in oncologic imaging: update on 5 common cancers

Imaging has become a pivotal component throughout a patient's encounter with cancer, from initial disease detection and characterization through treatment response assessment and posttreatment follow-up. Recent progress in imaging technology has presented new opportunities for improving clinical care. This article provides updates on the latest approaches to imaging of 5 common cancers: breast, lung, prostate, and colorectal cancers, and lymphoma.

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.

Screening for colorectal cancer: what fits best?

Colorectal cancer (CRC) screening has been shown to be effective in reducing CRC incidence and mortality. There are currently a number of screening modalities available for implementation into a population-based CRC screening program. Each screening method offers different strengths but also possesses its own limitations as a population-based screening strategy. We review the current evidence base for accepted CRC screening tools and evaluate their merits alongside their challenges in fulfilling their role in the detection of CRC. We also aim to provide an outlook on the demands of a low-risk population-based CRC screening program with a view to providing insight as to which modality would best suit current and future needs.

Molecular events in primary and metastatic colorectal carcinoma: a review

Colorectal cancer (CRC) is a heterogeneous disease, developing through a multipathway sequence of events guided by clonal selections. Pathways included in the development of CRC may be broadly categorized into (a) genomic instability, including chromosomal instability (CIN), microsatellite instability (MSI), and CpG island methylator phenotype (CIMP), (b) genomic mutations including suppression of tumour suppressor genes and activation of tumour oncogenes, (c) microRNA, and (d) epigenetic changes. As cancer becomes more advanced, invasion and metastases are facilitated through the epithelial-mesenchymal transition (EMT), with additional genetic alterations. Despite ongoing identification of genetic and epigenetic markers and the understanding of alternative pathways involved in the development and progression of this disease, CRC remains the second highest cause of malignancy-related mortality in Canada. The molecular events that underlie the tumorigenesis of primary and metastatic colorectal carcinoma are detailed in this manuscript.

Aberrant vimentin methylation is characteristic of upper gastrointestinal pathologies

BACKGROUND

We have previously established aberrant DNA methylation of vimentin exon-1 (VIM methylation) as a common epigenetic event in colon cancer and as a biomarker for detecting colon neoplasia. We now examine vimentin methylation in neoplasia of the upper gastrointestinal tract.

METHODS

Using a quantitative real-time methylation-specific PCR assay, we tested for vimentin methylation in archival specimens of esophageal and gastric neoplasia.

RESULTS

We find that acquisition of aberrant vimentin methylation is highly common in these neoplasms, but largely absent in controls. The highest frequency of vimentin methylation was detected in lesions of the distal esophagus, including 91% of Barrett's esophagus (n = 11), 100% of high-grade dysplasia (HGD, n = 5), and 81% of esophageal adenocarcinoma (EAC, n = 26) but absent in controls (n = 9). Vimentin methylation similarly was detected in 87% of signet ring (n = 15) and 53% of intestinal type gastric cancers (n = 17). Moreover, in tests of cytology brushings vimentin methylation proved detectable in 100% of Barrett's esophagus cases (n = 7), 100% of HGD cases (n = 4), and 83% of EAC cases (n = 18) but was absent in all controls (n = 5).

CONCLUSIONS

These findings establish aberrant vimentin methylation as a highly common epigenetic alteration in neoplasia of the upper gastrointestinal tract and show that Barrett's esophagus, even without dysplasia, already contains epigenetic alterations characteristic of adenocarcinoma.

IMPACT

These findings suggest vimentin methylation as a biomarker of upper gastrointestinal neoplasia with potential for development as molecular cytology in esophageal screening.

Epigenetic biomarkers of colorectal cancer: Focus on DNA methylation

The original theory of the multi-step process of colorectal cancer (CRC), suggesting that the disease resulted from the accumulation of mutations in oncogenes and tumor suppressor genes in colonic mucosa cells, has been largely revised following the observation that epigenetic modifications of several genes occur in the average CRC genome. Therefore, the current opinion is that CRCs are the consequence of the accumulation of both mutations and epigenetic modifications of several genes. This mini-review article focuses on DNA methylation biomarkers in CRC. Recent large-scale DNA methylation studies suggest that CRCs can be divided into at least three-four subtypes according to the frequency of DNA methylation and those of mutations in key CRC genes. Despite hundreds of genes might be epigenetically modified in CRC cells, there is interest in the identification of DNA methylation biomarkers to be used for CRC diagnosis, progression, tendency to tissue invasion and metastasis, prognosis, and response to chemotherapeutic agents. Moreover, DNA methylation largely depends on one-carbon metabolism, the metabolic pathway required for the production of S-adenosylmethionine, the major intracellular methylating agent. Complex interactions are emerging among dietary one-carbon nutrients (folates, vitamin B6, vitamin B12, methionine, and others), their metabolic genes, CRC risk, and DNA methylation profiles in CRC. Moreover, active research is also focused on the possible contribution of folic acid dietary fortification during pregnancy and the possible methylation of CRC-related genes in the offspring.

Quantification of methylated markers with a multiplex methylation-specific technology

BACKGROUND

Aberrantly methylated genes represent important markers for cancer diagnosis. We describe a multiplex detection approach to efficiently quantify these markers for clinical applications such as colorectal cancer screening.

METHODS

Quantitative allele-specific real-time target and signal amplification (QuARTS) combines a polymerase-based target amplification with an invasive cleavage-based signal amplification. The fluorescence signal is detected in a fashion similar to real-time PCR. We measured the dynamic range and analytical sensitivity of multiplex QuARTS reactions with titrated plasmid DNA. We used the QuARTS technology to quantify methylated BMP3, NDRG4, VIM, and TFPI2 genes on 91 DNA samples extracted from colorectal tissues, including 37 cancers, 25 adenomas, and 29 healthy epithelia. The assays were designed in triplex format that incorporated ACTB as a reference gene. Percent methylation was calculated by dividing methylated strands over ACTB strands and multiplying by 100.

RESULTS

The QuARTS method linearly detected methylated or unmethylated VIM gene down to 10 copies. No cross-reactivity was observed when methylated assays were used to amplify 10(5) copies of unmethylated gene and vice versa. The multiplex assay detected methylated genes spiked in unmethylated genes at a 0.01% ratio and vice versa. At a diagnostic specificity cutoff of 95%, methylated BMP3, NDRG4, VIM, and TFPI2 detected 84%, 92%, 86%, and 92% of colorectal cancers and 68%, 76%, 76%, and 88% of adenomas, respectively.

CONCLUSIONS

The QuARTS technology provides a promising approach for quantifying methylated markers. The markers assayed highly discriminated colorectal neoplasia from healthy epithelia.

Genetic and epigenetic traits as biomarkers in colorectal cancer

Colorectal cancer is a major health burden, and a leading cause of cancer-related deaths in industrialized countries. The steady improvements in surgery and chemotherapy have improved survival, but the ability to identify high- and low-risk patients is still somewhat poor. Molecular biology has, over the years, given insight into basic principles of colorectal cancer initiation and development. These findings include aberrations increasing risk of tumor development, genetic changes associated with the stepwise progression of the disease, and errors predicting response to a specific treatment. Potential biomarkers in colorectal cancer are extensively studied, and how the molecular aberrations relate to clinical features. Yet, little of this knowledge has been possible to transfer into clinical practice. In this review, an overview of colorectal cancer genetics will be given, as well as how aberrations found in this tumor type are proposed as biomarkers for risk prediction, as diagnostic tools, for prognosis or prediction of treatment outcome.

Aberrant methylation of genes in stool samples as diagnostic biomarkers for colorectal cancer or adenomas: a meta-analysis

BACKGROUND

An increasing number of hypermethylated genes in stool samples have been reported as biomarkers for the detection of colorectal cancer (CRC) or adenomas. We aimed to comprehensively review and compare the evidence for feasibility of using these biomarkers for the detection of colorectal neoplasia.

METHODS

We searched Medline, the Web of Science and OVID for studies that used hypermethylated genes as biomarkers for the detection of CRC or adenomas. A meta-analysis was carried out using the random-effect model with diagnostic odd ratios (DOR) and 95% confidence intervals (CI) as effect measurements.

RESULTS

A total of 19 studies including 2,356 patients were eligible for final analysis. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and DOR for the detection of CRC or adenomas were 0.62 (95% CI: 0.51-0.71), 0.89 (95% CI: 0.86-0.92), 5.66 (95% CI: 4.68-6.83), 0.43 (95% CI: 0.34-0.55) and 13.15 (95% CI: 9.82-17.60) respectively. Of these, the sensitivity and specificity for the detection of adenoma were 0.54 (95% CI: 0.39-0.68) and 0.88 (95% CI: 0.83-0.92) respectively.

CONCLUSIONS

Hypermethylated gene panels are not currently accurate enough to be used alone for colorectal neoplasia screening. The discovery and evaluation of additional biomarkers with improved sensitivity and specificity is necessary.

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.

New faecal tests in gastroenterology

Most abdominal disorders present with a limited number of overlapping symptoms. Blood tests are not routinely available for use in diagnosis and so investigation tends to require complex imaging procedures or endoscopy and biopsy. These are invasive for the patient, may be associated with morbidity and mortality and have considerable resource implications. Biochemical tests on a single sample of faeces are therefore a valuable alternative. Measurement of faecal calprotectin has been shown to have a role in the diagnosis of inflammatory bowel disease and in its monitoring. Lactoferrin is also of benefit used in this way. Faecal elastase has been demonstrated to be of use in the diagnosis of pancreatic insufficiency. A number of faecal markers have been explored in colorectal cancer. Faecal occult blood testing is used for population screening, but the metabolomic marker tumour, M2-pyruvate kinase, has potential for use in both diagnosis and screening. DNA testing has advantages in colorectal cancer but the exact applications of such tests require further evaluation.

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.

Epigenetics and colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. It results from an accumulation of genetic and epigenetic changes in colon epithelial cells, which transforms them into adenocarcinomas. Over the past decade, major advances have been made in understanding cancer epigenetics, particularly regarding aberrant DNA methylation. Assessment of the colon cancer epigenome has revealed that virtually all CRCs have aberrantly methylated genes and that the average CRC methylome has hundreds to thousands of abnormally methylated genes. As with gene mutations in the cancer genome, a subset of these methylated genes, called driver genes, is presumed to have a functional role in CRC. The assessment of methylated genes in CRCs has also revealed a unique molecular subgroup of CRCs called CpG island methylator phenotype (CIMP) cancers; these tumors have a particularly high frequency of methylated genes. These advances in our understanding of aberrant methylation in CRC have led to epigenetic alterations being developed as clinical biomarkers for diagnostic, prognostic and therapeutic applications. Progress in this field suggests that these epigenetic alterations will be commonly used in the near future to direct the prevention and treatment of 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.

Cost-effectiveness of colorectal cancer screening

Colorectal cancer is an important public health problem. Several screening methods have been shown to be effective in reducing colorectal cancer mortality. The objective of this review was to assess the cost-effectiveness of the different colorectal cancer screening methods and to determine the preferred method from a cost-effectiveness point of view. Five databases (MEDLINE, EMBASE, the Cost-Effectiveness Analysis Registry, the British National Health Service Economic Evaluation Database, and the lists of technology assessments of the Centers for Medicare and Medicaid Services) were searched for cost-effectiveness analyses published in English between January 1993 and December 2009. Fifty-five publications relating to 32 unique cost-effectiveness models were identified. All studies found that colorectal cancer screening was cost-effective or even cost-saving compared with no screening. However, the studies disagreed as to which screening method was most effective or had the best incremental cost-effectiveness ratio for a given willingness to pay per life-year gained. There was agreement among studies that the newly developed screening tests of stool DNA testing, computed tomographic colonography, and capsule endoscopy were not yet cost-effective compared with the established screening options.

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.

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 testing for Colorectal Cancer Screening: the ColoSure™ test

Colorectal cancer is the third most common cancer and the second leading cause of cancer-related deaths in the United States. Screening has been shown to be effective in reducing colorectal cancer incidence and mortality. Colonoscopy, sigmoidoscopy, and fecal occult blood tests are all recommended screening tests that have widespread availability. Nevertheless, many people do not receive the evidence-based recommended screening for colorectal cancer. Additional stool-based methods have been developed that offer more options for colorectal cancer screening, including a variety of fecal DNA tests. The only fecal DNA test that is currently available commercially in the United States is ColoSure(TM), which is marketed as a non-invasive test that detects an epigenetic marker (methylated vimentin) associated with colorectal cancer and pre-cancerous adenomas. We examined the published literature on the analytic validity, clinical validity, and clinical utility of ColoSure and we briefly summarized the current colorectal cancer screening guidelines regarding fecal DNA testing. We also addressed the public health implications of the test and contextual issues surrounding the integration of fecal DNA testing into current colorectal cancer screening strategies. The primary goal was to provide a basic overview of ColoSure and identify gaps in knowledge and evidence that affect the recommendation and adoption of the test in colorectal cancer screening strategies.

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.

Quantitative denaturing high performance liquid chromatography (Q-dHPLC) detection of APC long DNA in faeces from patients with colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths. However, prevention is possible by early detection. In the present work, we have demonstrated and validated a novel quantitative method based on a DNA integrity assay and mutation in faeces of CRC patients using denaturing high performance liquid chromatography (dHPLC).

METHODS

Faecal DNA (fDNA) was isolated from 28 CRC, 96 healthy and 61 patients with adenomas. Adenomatosis polyposis coli (APC)-Long-DNA and its mutations were analysed using dHPLC and the Sanger sequencing method. The diagnostic performance was assessed using receiver operating characteristic curve analysis.

RESULTS

We detected APC-Long-DNA in 21/28 CRC subjects with a sensitivity of 75% and specificity of 91.7%. A cut-off ratio of 0.2317 was used for APC/β-actin. The Q-dHPLC detection limit was 0.02 ng/injection. The average initial fDNA presence based on a single gene of β-actin was 26.12 ± 13.39 ng/mL for healthy, and 49.61 ± 46.28 ng/mL for CRC subjects, with a sensitivity of 71.4% and a specificity of 84.4% at a cut-off value >29 ng/mL. We also detected a novel mutation at codon 1576 Lys/Glu using dHPLC.

CONCLUSIONS

This study highlights a novel application of Q-dHPLC in the DNA integrity assay, which demonstrates high performance, good reproducibility, and low cost for the CRC detection using faeces. Further studies in a larger population are needed to confirm these results.

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.

Stool DNA testing to screen for colorectal cancer in the Medicare population: a cost-effectiveness analysis

BACKGROUND

The Centers for Medicare & Medicaid Services considered whether to reimburse stool DNA testing for colorectal cancer screening among Medicare enrollees.

OBJECTIVE

To evaluate the conditions under which stool DNA testing could be cost-effective compared with the colorectal cancer screening tests currently reimbursed by the Centers for Medicare & Medicaid Services.

DESIGN

Comparative microsimulation modeling study using 2 independently developed models.

DATA SOURCES

Derived from literature.

TARGET POPULATION

A cohort of persons aged 65 years. A sensitivity analysis was also conducted, in which a cohort of persons aged 50 years was studied.

TIME HORIZON

Lifetime.

PERSPECTIVE

Third-party payer.

INTERVENTION

Stool DNA test every 3 or 5 years in comparison with currently recommended colorectal cancer screening strategies.

OUTCOME MEASURES

Life expectancy, lifetime costs, incremental cost-effectiveness ratios, and threshold costs.

RESULTS OF BASE-CASE ANALYSIS

Assuming a cost of $350 per test, strategies of stool DNA testing every 3 or 5 years yielded fewer life-years and higher costs than the currently recommended colorectal cancer screening strategies. Screening with the stool DNA test would be cost-effective at a per-test cost of $40 to $60 for stool DNA testing every 3 years, depending on the simulation model used. There were no levels of sensitivity and specificity for which stool DNA testing would be cost-effective at its current cost of $350 per test. Stool DNA testing every 3 years would be cost-effective at a cost of $350 per test if the relative adherence to stool DNA testing were at least 50% better than that with other screening tests.

RESULTS OF SENSITIVITY ANALYSIS

None of the results changed substantially when a cohort of persons aged 50 years was considered.

LIMITATION

No pathways other than the traditional adenoma-carcinoma sequence were modeled.

CONCLUSION

Stool DNA testing could be a cost-effective alternative for colorectal cancer screening if the cost of the test substantially decreased or if its availability would entice a large fraction of otherwise unscreened persons to receive screening.