Serum Tests for Colorectal Cancer Screening

Gel-Based Proteomics of Clinical Samples Identifies Potential Serological Biomarkers for Early Detection of Colorectal Cancer

The burden of colorectal cancer (CRC) is considerable-approximately 1.8 million people are diagnosed each year with CRC and of these about half will succumb to the disease. In the case of CRC, there is strong evidence that an early diagnosis leads to a better prognosis, with metastatic CRC having a 5-year survival that is only slightly greater than 10% compared with up to 90% for stage I CRC. Clearly, biomarkers for the early detection of CRC would have a major clinical impact. We implemented a coherent gel-based proteomics biomarker discovery platform for the identification of clinically useful biomarkers for the early detection of CRC. Potential protein biomarkers were identified by a 2D gel-based analysis of a cohort composed of 128 CRC and site-matched normal tissue biopsies. Potential biomarkers were prioritized and assays to quantitatively measure plasma expression of the candidate biomarkers were developed. Those biomarkers that fulfilled the preset criteria for technical validity were validated in a case-control set of plasma samples, including 70 patients with CRC, adenomas, or non-cancer diseases and healthy individuals in each group. We identified 63 consistently upregulated polypeptides (factor of four-fold or more) in our proteomics analysis. We selected 10 out of these 63 upregulated polypeptides, and established assays to measure the concentration of each one of the ten biomarkers in plasma samples. Biomarker levels were analyzed in plasma samples from healthy individuals, individuals with adenomas, CRC patients, and patients with non-cancer diseases and we identified one protein, tropomyosin 3 (Tpm3) that could discriminate CRC at a significant level (p = 0.0146). Our results suggest that at least one of the identified proteins, Tpm3, could be used as a biomarker in the early detection of CRC, and further studies should provide unequivocal evidence for the real-life clinical validity and usefulness of Tpm3.

Proteomics for early detection of colorectal cancer: recent updates

INTRODUCTION

Colorectal cancer (CRC) is a common type of cancer with a relatively poor survival rate. The survival rate of patients could be improved if CRC is detected early. Biomarkers associated with early stages of tumor development might provide useful tools for the early diagnosis of colorectal cancer. Areas covered: Online searches using PubMed and Google Scholar were performed using keywords and with a focus on recent proteomic studies. The aim of this review is to highlight the need for biomarkers to improve the detection rate of early CRC and provide an overview of proteomic technologies used for biomarker discovery and validation. This review will also discuss recent proteomic studies which focus on identifying biomarkers associated with the early stages of CRC development. Expert commentary: A large number of CRC biomarkers are increasingly being identified by proteomics using diverse approaches. However, the clinical relevance and introduction of these markers into clinical practice cannot be determined without a robust validation process. The size of validation cohorts remains a major limitation in many biomarker studies.

Photonic crystal materials and their application in biomedicine

Photonic crystal (PC) materials exhibit unique structural colors that originate from their intrinsic photonic band gap. Because of their highly ordered structure and distinct optical characteristics, PC-based biomaterials have advantages in the multiplex detection, biomolecular screening and real-time monitoring of biomolecules. In addition, PCs provide good platforms for drug loading and biomolecule modification, which could be applied to biosensors and biological carriers. A number of methods are now available to fabricate PC materials with variable structure colors, which could be applied in biomedicine. Emphasis is given to the description of various applications of PC materials in biomedicine, including drug delivery, biodetection and tumor screening. We believe that this article will promote greater communication among researchers in the fields of chemistry, material science, biology, medicine and pharmacy.

Integrative analysis of the colorectal cancer proteome: potential clinical impact

INTRODUCTION

Colorectal cancer (CRC) is one of the common types of cancer that affects a significant proportion of the population and is a major contributor to cancer related mortality. The relatively poor survival rate of CRC could be improved through the identification of clinically useful biomarkers. Areas covered: This review highlights the need for biomarkers and discusses recent proteomics discoveries in the aspects of CRC clinical practice including diagnosis, prognosis, therapy, screening and molecular pathological epidemiology (MPE). Studies have been evaluated in relation to biomarker target, methodology, sample selection, limitations, and potential impact. Finally, the progress in proteomic approaches is briefly discussed and the main difficulties facing the translation of proteomics biomarkers into the clinical practice are highlighted. Expert commentary: The establishment of specific guidelines, best practice recommendations and the improvement in proteomic strategies will significantly improve the prospects for developing clinically useful biomarkers.

Evaluation of serum nucleoside diphosphate kinase A for the detection of colorectal cancer

We previously described the over-expression of nucleoside diphosphate kinase A (NDKA) in tumours and serum from colorectal cancer (CRC) patients, suggesting its use as biomarker. In this study we evaluated the diagnostic accuracy of serum NDKA to detect advanced neoplasia (CRC or advanced adenomas). Furthermore, the performance of NDKA was compared with the faecal immunochemical test (FIT). The study population included a case-control cohort and a screening cohort (511 asymptomatic first-degree relatives of CRC patients that underwent a colonoscopy and a FIT). Serum NDKA was elevated in CRC patients in the case-control cohort (p = 0.002). In the screening cohort, NDKA levels were higher for advanced adenomas (p = 0.010) and advanced neoplasia (p = 0.006) compared to no neoplasia. Moreover, elevated NDKA was associated with severe characteristics of adenomas (≥3 lesions, size ≥ 1 cm or villous component). Setting specificity to 85%, NDKA showed a sensitivity of 30.19% and 29.82% for advanced adenomas and advanced neoplasia, respectively. NDKA combined with FIT (100 ng/mL cut-off) detected advanced adenomas and advanced neoplasia with 45.28% and 49.12% sensitivity, with specificity close to 90%. The combination of serum NDKA and FIT can improve the detection of advanced neoplasia, mainly for lesions located on the proximal colon, in asymptomatic individuals with CRC family-risk.

Blood-based screening for bowel cancer may not resolve suboptimal screening participation in Australia

OBJECTIVE

Emerging blood-based screening technologies for bowel cancer may improve screening participation compared to at-home stool sampling. This study assessed the impact of different screening delivery scenarios with increasing health system interactions on sampling preferences and likelihood of screening participation.

METHODS

N=1,561 persons aged 45 to 74 years completed a behavioural survey measuring demographics, readiness to screen, overall collection method preference, and proposed participation in stool and blood methods across four screening scenarios differing in terms of the number of required health system interactions.

RESULTS

Overall, respondents preferred a blood test (79.6%) compared to a stool test (20.4%). However, increasing health system interactions had a strong impact on the likelihood of participating in either sampling method (p<0.001). Moreover, likelihood of participating in each of the four blood-screening scenarios was significantly lower than the current at-home stool sampling approach (all p<0.001).

CONCLUSIONS

Blood-based screening methods require increased contact with the health system but these interactions have negative impact on screening likelihood. All blood-based scenarios showed lower screening likelihood ratings than the current at-home FIT approach. Thus, blood-based screening may not resolve suboptimal screening participation rates in Australia.

Clinical Relevance of Plasma DNA Methylation in Colorectal Cancer Patients Identified by Using a Genome-Wide High-Resolution Array

BACKGROUND

DNA methylation is a potential tumor marker for several cancers, including colorectal cancer (CRC), because of its heritable and stable characteristics.

METHODS

Using a high-resolution, genome-wide approach, we epigenotyped >450,000 CpG sites in tumor and adjacent non-tumor tissues from 23 microsatellite instability (MSI)/microsatellite stability (MSS) CRC cases. Using matrix-assisted laser desorption ionization-time of flight mass spectrometry, the methylation status of five frequently hypermethylated genes were confirmed in 75 independent CRC series and 353 CRC patients with available plasma.

RESULTS

Compared with non-tumor tissues, 13 MSI tumors had 34,836 (7 %) aberrant methylation sites, 87 % of which were hypermethylated. In contrast, only 9,806 (2 %) differentially methylated sites were identified in ten MSS cases (62 % hypermethylated). In both MSI and MSS, 228 promoter-associated CpG islands were hypermethylated, with AGBL4, ZNF625, MDFI, TWIST1, and FLI1 being most frequently hypermethylated. In an independent set of 35 MSI and 40 MSS cases, the methylation status of these five genes significantly differed between tumor and adjacent non-tumor tissues. Of 353 CRC patients, 230 (65.2 %), 232 (65.7 %), and 247 (70.0 %) had AGBL4, FLI1, and TWIST1 promoter hypermethylation in circulating cell-free DNA, respectively. In patients without metastasis, the sensitivity of any two or three hypermethylation markers was 52.8-57.8 and 27.9-38.9 %, respectively. The sensitivity of any two or three markers was significantly high in patients with stage IV disease (73.0 and 55.6 %, respectively). The prognostic value of these epimarkers was inconclusive.

CONCLUSION

DNA methylation patterns differed in CRC subtypes. The identified hypermethylation markers in CRC patients may have good sensitivity in different CRC stages.

Validation of a real-time PCR-based qualitative assay for the detection of methylated SEPT9 DNA in human plasma

BACKGROUND

Epi proColon® is a new blood-based colorectal cancer (CRC) screening test designed to determine the methylation status of a promoter region of the SEPT9 (septin 9) gene in cell-free DNA isolated from plasma. We describe the analytical and clinical performance of the test.

METHODS

Analytical performance at 4 testing laboratories included determination of limit of detection, precision, and reproducibility of the SEPT9 test. Clinical performance was evaluated in a prospective study by use of samples (n = 1544) from subjects enrolled in the PRESEPT clinical trial. Results were analyzed by comparison with colonoscopy, the reference standard.

RESULTS

The limit of detection for methylated SEPT9 DNA was 7.8 pg/mL (95% CI 6-11 pg/mL) corresponding to <2 genome copies of methylated SEPT9 per milliliter of plasma. In the prospective clinical trial, sensitivity for all stages of CRC was 68% (95% CI 53%-80%) and for stage I-III CRC, 64% (48%-77%). Adjusted specificity, on the basis of negative colonoscopy findings, was 80.0% (78%-82%).

SIGNIFICANCE

The Epi proColon test is a simple, real-time PCR-based assay for the detection of methylated SEPT9 DNA in blood that may provide a noninvasive CRC screening alternative for people noncompliant with current CRC screening guidelines.

Cost-effectiveness of colorectal cancer screening in Germany: current endoscopic and fecal testing strategies versus plasma methylated Septin 9 DNA

BACKGROUND AND STUDY AIMS

Colorectal cancer (CRC) screening strategies in Germany include guaiac-based fecal occult blood testing (gFOBT) starting at age 50 and a switch to colonoscopy at age 55 or continued gFOBT testing, but screening utilization is limited. Blood-based biomarkers, such as methylated Septin 9 DNA ( (m) SEPT9), may improve screening rates. We performed a cost-effectiveness analysis of current and emerging CRC screening strategies in Germany.

METHODS

Using a validated Markov model, we compared annual gFOBT for ages 50 through 54 followed by biennial testing until age 75 (FOBT) or by colonoscopy at ages 55 and 65 (FOBT/COLO 55,65), substitution of fecal immunochemical testing (FIT) for gFOBT (FIT, FIT/COLO 55,65), and annual or biennial plasma (m) SEPT9 testing. We also considered persons who utilize only colonoscopy and varied age at colonoscopy utilization.

RESULTS

The current strategies were more effective and less costly than no screening. FIT was more effective and less costly than (m) SEPT9 testing. FIT/COLO 55,65 cost €12 200 per quality-adjusted life-years gained in comparison with FIT. (m) SEPT9-based screening was cost-effective in comparison with no screening but was dominated by other cost-saving strategies. Differential screening utilization and adherence greatly affected incremental results between strategies. In probabilistic analyses, FIT was preferred in 49 % and FIT/COLO 55,65 in 47 % of iterations.

CONCLUSION

Currently available CRC screening strategies in Germany, including hybrid fecal testing/colonoscopy, are likely to be cost-saving. Current strategies appear superior to (m) SEPT9-based screening. The impact of blood-based biomarkers is likely to depend on utilization and adherence as much as on test performance characteristics and cost.

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.

Relationship between tumor and peripheral blood NPRL2 mRNA levels in patients with colorectal adenoma and colorectal cancer

NPRL2 is a tumor suppressor gene involved in the progression of human cancer. The present study investigated whether NPRL2 expression correlates with colorectal cancer (CRC) progression. Colorectal tissue and peripheral blood samples were obtained from 62 patients with CRC, 38 patients with colorectal adenomas and 51 normal controls. NPRL2 mRNA levels in tissue samples and blood were measured using quantitative real-time PCR. NPRL2 protein expression was determined by immunohistochemistry. NPRL2 protein expression in CRCs was significantly lower than in the adenomas or normal colorectal tissue. NPRL2 mRNA expression was significantly decreased in adenomas compared with normal controls (P<0.0001) and it was further decreased in colorectal tumors compared with adenomas (P<0.0001). NPRL2 mRNA levels expression correlated with tumor stage. In addition, NPRL2 mRNA levels in the blood correlated with the levels detected in tumors. Furthermore, receiver operating characteristic (ROC) analysis showed that NPRL2 expression in blood could distinguish colorectal adenomas and CRCs from normal controls. NPRL2 mRNA expression in CRC tumor tissues and peripheral blood correlated with colorectal tumor progression. Based on our findings, we can conclude that NPRL2 mRNA blood levels could be a potentially useful marker for the detection of early stage adenomas and CRCs.

Developing proteomics-based biomarkers for colorectal neoplasms for clinical practice: opportunities and challenges

Colorectal cancer (CRC) arises from the normal colon epithelium through the accumulation of genetic mutations and epigenetic alterations that are associated with progression along the histological adenoma-adenocarcinoma sequence. Elucidating the molecular alterations underlying disease progression will not only provide insight into the behavior of the tumors, but also could lead to the discovery of useful biomarkers for diagnosis, monitoring treatment responsiveness, or predicting disease outcomes. In the past a few years, there have been several evaluating differentially expressed protein biomarkers by employing proteomics technologies coupled with mass spectrometry. In the current review, we will briefly summarize the results from selected recent studies using tissue or serum samples from CRC patients in the past 5 years and discuss the opportunities and challenges in translating these findings from the research setting to clinical practice.

Simple patterned nanofiber scaffolds and its enhanced performance in immunoassay

Cancer has become the leading cause of death worldwide; early diagnosis and treatment of cancers is critical for the survival of the patients. The concentration of cancer markers in easy-to-access biological fluids can provide great assistance in screening for occult primary cancers, distinguishing malignant from benign findings, determining prognosis and prediction for cancer patients. The multiplex detection technology of a panel of cancer markers can greatly increase the accuracy of disease diagnosis. Herein, we briefly fabricate a high-throughput micro-immunoassay based on the electrospun polystyrene (PS) substrates to improve detection sensitivity. The immunoassay was evaluated by analyzing three different cancer biomarkers (AFP, CEA, VEGF). For AFP, CEA, VEGF immunofluorescence assay, the LOD of assay conducted on electrospun PS substrates before or after plasma and the conventional PS substrates were 0.42, 0.10, 1.12 ng/mL, 0.57, 0.09, 1.24 ng/mL, and 159.75, 26.19, 385.59 pg/mL, respectively (P < 0.05). Due to the high porosity and large surface area-to-volume ratio which is the foremost merit of nanostructures, and the plasma treatment which make the hydrophobic PS nanofibers hydropholic, the nanofibers substrates showed sufficient retention of immunoassay functionality and high potential for capture molecules immobilization. Consequently, the immunofluorescence assay conducted on electrospun PS substrates could significantly enhance the sensitivity and limits of detection.

Multiplexed VeraCode bead-based serological immunoassay for colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the US and Western world. Despite increased screening and advances in treatment, the mortality rate (ca. 50,000/year) and high national health-care burden for CRC are likely to remain high unless an effective non-invasive screening test for CRC is instituted for a large segment of the population. Blood-based protein biomarkers hold great promise for early disease diagnosis and personalized medicine; yet robust and reproducible multiplexing platforms and methodologies have lagged behind their genomic counterparts. Here, we report the development of a novel, multiplexed, hybrid immunoassay for CRC that is formatted on barcoded VeraCode™ micro-beads, which have until now only been used for genomic assays. The method combines a sandwich immunoassay format for detection of serum protein biomarkers with an antigen assay for autoantibody detection. The serum protein biomarkers CEA and GDF15 as well as autoantibodies to the p53 tumor associated antigen (TAA) were used to exemplify the method. This multiplex biomarker panel was configured to run on Illumina's holographically barcoded VeraCode™ micro-bead platform, which is capable of measuring hundreds of analytes simultaneously in a single well from small volumes of blood (<50 μL) using a 96-well industry standard microtiter plate. This novel use of the VeraCode™ micro-bead platform translates into a potentially low volume, high throughput, multiplexed assay for CRC, for the purposes of biomarker validation, as well as patient screening, diagnostics and prognostics. In an evaluation of a 186 patient sera training set (CRC and normal), we obtained a diagnostic sensitivity of 54% and a specificity of 98%. We anticipate that by expanding and refining the biomarkers in this initial panel, and performing more extensive clinical validations, such an assay could ultimately provide a basis for CRC population screening to complement the more invasive, expensive and low throughput (but highly sensitive and specific) colonoscopy.

Colorectal cancer screening with blood-based biomarkers: cost-effectiveness of methylated septin 9 DNA versus current strategies

BACKGROUND

Screening reduces colorectal cancer mortality, but many persons remain unscreened. Screening with a blood test could improve screening rates. We estimated the comparative effectiveness and cost-effectiveness of colorectal cancer screening with emerging biomarkers, illustrated by a methylated Septin 9 DNA plasma assay ((m)SEPT9), versus established strategies.

METHODS

We conducted a cost-utility analysis using a validated decision analytic model comparing (m)SEPT9, fecal occult blood testing (FOBT), fecal immunochemical testing (FIT), sigmoidoscopy, and colonoscopy, projecting lifetime benefits and costs.

RESULTS

In the base case, (m)SEPT9 decreased colorectal cancer incidence by 35% to 41% and colorectal cancer mortality by 53% to 61% at costs of $8,400 to $11,500/quality-adjusted life year gained versus no screening. All established screening strategies were more effective than (m)SEPT9. FIT was cost saving, dominated (m)SEPT9, and was preferred among all the alternatives. Screening uptake and longitudinal adherence rates over time strongly influenced the comparisons between strategies. At the population level, (m)SEPT9 yielded incremental benefit at acceptable costs when it increased the fraction of the population screened more than it was substituted for other strategies.

CONCLUSIONS

(m)SEPT9 seems to be effective and cost-effective compared with no screening. To be cost-effective compared with established strategies, (m)SEPT9 or blood-based biomarkers with similar test performance characteristics would need to achieve substantially higher uptake and adherence rates than the alternatives. It remains to be proven whether colorectal cancer screening with a blood test can improve screening uptake or long-term adherence compared with established strategies.

IMPACT

Our study offers insights into the potential role of colorectal cancer screening with blood-based biomarkers.

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.