Testing of multiple samples increases the sensitivity of stool decay-accelerating factor test for the detection of colorectal cancer

Identifying Novel Biomarkers Ready for Evaluation in Low-Prevalence Populations for the Early Detection of Lower Gastrointestinal Cancers: A Systematic Review and Meta-Analysis

INTRODUCTION

Lower gastrointestinal (GI) cancers are a major cause of cancer deaths worldwide. Prognosis improves with earlier diagnosis, and non-invasive biomarkers have the potential to aid with early detection. Substantial investment has been made into the development of biomarkers; however, studies are often carried out in specialist settings and few have been evaluated for low-prevalence populations.

METHODS

We aimed to identify novel biomarkers for the detection of lower GI cancers that have the potential to be evaluated for use in primary care. MEDLINE, Embase, Emcare and Web of Science were systematically searched for studies published in English from January 2000 to October 2019. Reference lists of included studies were also assessed. Studies had to report on measures of diagnostic performance for biomarkers (single or in panels) used to detect colorectal or anal cancers. We included all designs and excluded studies with fewer than 50 cases/controls. Data were extracted from published studies on types of biomarkers, populations and outcomes. Narrative synthesis was used, and measures of specificity and sensitivity were meta-analysed where possible.

RESULTS

We identified 142 studies reporting on biomarkers for lower GI cancers, for 24,844 cases and 45,374 controls. A total of 378 unique biomarkers were identified. Heterogeneity of study design, population type and sample source precluded meta-analysis for all markers except methylated septin 9 (mSEPT9) and pyruvate kinase type tumour M2 (TuM2-PK). The estimated sensitivity and specificity of mSEPT9 was 80.6% (95% CI 76.6-84.0%) and 88.0% (95% CI 79.1-93.4%) respectively; TuM2-PK had an estimated sensitivity of 81.6% (95% CI 75.2-86.6%) and specificity of 80.1% (95% CI 76.7-83.0%).

CONCLUSION

Two novel biomarkers (mSEPT9 and TuM2-PK) were identified from the literature with potential for use in lower-prevalence populations. Further research is needed to validate these biomarkers in primary care for screening and assessment of symptomatic patients.

Fecal Immunochemical Tests Combined With Other Stool Tests for Colorectal Cancer and Advanced Adenoma Detection: A Systematic Review

OBJECTIVES

Despite moderate to high detection rates of fecal immunochemical tests (FITs) of colorectal cancer (CRC), detection of adenomas remains limited. Further stool tests exist, which are not used in routine practice, such as DNA or RNA markers and protein markers. We aimed at systematically investigating and summarizing evidence for diagnostic performance of combinations of FIT with other stool tests compared with FIT alone in early detection of CRC and its precursors.

METHODS

We systematically reviewed studies that evaluated FITs in combination with other stool tests and compared measures of diagnostic accuracy with and without additional stool tests. PubMed and Web of Science were searched from inception to May 2015. Reference lists of eligible studies were also screened. Two reviewers extracted data independently.

RESULTS

Some of the reports on DNA, RNA, or tissue tests, including tests based on DNA mutations, methylation, and integrity in selected genes as well as microRNA expression, showed some improvements of diagnostic test accuracy. In contrast, so far assessed stool protein markers did generally not lead to substantial improvements in performance of FIT when added to the latter. Many marker combinations were reported only in one study each, and few studies were conducted in a true screening setting.

CONCLUSIONS

Several stool markers show potential to improve performance of FITs. However, the results require confirmation in further studies, which should also evaluate the costs and cost-effectiveness of combined screening strategies.

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.

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.

Biological and functional analysis of statistically significant pathways deregulated in colon cancer by using gene expression profiles

Gene expression profiling offers a great opportunity for studying multi-factor diseases and for understanding the key role of genes in mechanisms which drive a normal cell to a cancer state. Single gene analysis is insufficient to describe the complex perturbations responsible for cancer onset, progression and invasion. A deeper understanding of the mechanisms of tumorigenesis can be reached focusing on deregulation of gene sets or pathways rather than on individual genes. We apply two known and statistically well founded methods for finding pathways and biological processes deregulated in pathological conditions by analyzing gene expression profiles. In particular, we measure the amount of deregulation and assess the statistical significance of predefined pathways belonging to a curated collection (Molecular Signature Database) in a colon cancer data set. We find that pathways strongly involved in different tumors are strictly connected with colon cancer. Moreover, our experimental results show that the study of complex diseases through pathway analysis is able to highlight genes weakly connected to the phenotype which may be difficult to detect by using classical univariate statistics. Our study shows the importance of using gene sets rather than single genes for understanding the main biological processes and pathways involved in colorectal cancer. Our analysis evidences that many of the genes involved in these pathways are strongly associated to colorectal tumorigenesis. In this new perspective, the focus shifts from finding differentially expressed genes to identifying biological processes, cellular functions and pathways perturbed in the phenotypic conditions by analyzing genes co-expressed in a given pathway as a whole, taking into account the possible interactions among them and, more importantly, the correlation of their expression with the phenotypical conditions.

Decay-accelerating factor (CD55): a versatile acting molecule in human malignancies

The decay-accelerating factor (DAF, CD55) physiologically serves as an inhibitor of the complement system. Moreover, DAF is broadly expressed in malignant tumors. Here, DAF seems to dispose of several different functions reaching far beyond its immunological role, e.g., promotion of tumorigenesis, decrease of complement mediated tumor cell lysis, autocrine loops for cell rescue and evasion of apoptosis, neoangiogenesis, invasiveness, cell motility, and metastasis via oncogenic tyrosine kinase pathway activation, and specific seven-span transmembrane receptors (CD97) binding. Furthermore, DAF has already been included in diagnostic or therapeutic studies. Thereby, studies applying monoclonal anti-DAF antibodies and anti-DAF vaccination for a targeted therapy have been enrolled recently.

New stool tests for colorectal cancer screening: a systematic review focusing on performance characteristics and practicalness

New stool tests may be promising tools for future colorectal cancer (CRC) screening. The aim of this review was to summarize current evidence of performance characteristics and practicalness in a population-based screening setting of recently developed stool tests. The MEDLINE database was searched for relevant articles published until July 2004. Studies were included if they comprised more than 10 cases and more than 10 controls. Details on study population, performance characteristics and stool collection procedure were taken into account. Overall, 29 studies, mostly retrospective, were included, investigating 17 different stool markers or marker combinations. Underlying study populations were very heterogeneous and mostly very small. Half of the studies reported sensitivity for adenomas in addition to sensitivity for CRC, and fewer than half reported sensitivity by tumor stage or location. Performance characteristics of stool tests varied to a large extent. For most DNA-based markers, specificity was about 95% or higher, but sensitivity was mostly low even for invasive CRC. More studies with larger sample sizes were done for protein-based markers, which typically had lower specificity. In most studies, stool samples were frozen within a rather short time period after defecation. While promising performance characteristics have been reported for some tests, more pervasive evidence from larger, prospectively designed studies, which also consider aspects of practicalness, e.g., the possibility of mailing the samples, is needed.

Noninvasive testing for colorectal cancer: a review

OBJECTIVES

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the United States. Endoscopic screening is now in favor and its use is increasing, but overall participation rates are poor. A substantial percentage of the population will likely continue to resist endoscopic screening. As such, a noninvasive biomarker for the early detection of CRC remains a priority. Herein, we (i) review the currently available noninvasive screening markers for the early detection of CRC, (ii) discuss newer markers that have undergone preliminary testing, and (iii) introduce and explain potentially promising markers of the future.

METHODS

The published literature on markers for early detection of CRC was identified using a MEDLINE/PubMed search with secondary review of cited publications.

RESULTS

Noninvasive testing for CRC is most advanced in testing for stool fecal occult blood, globin, or DNA mutations. Study of abnormal mucins has also been explored. Research for serum-based markers is just beginning and includes serum proteomics, nuclear matrix proteins, and serum DNA testing.

CONCLUSIONS

Serial guaiac-based fecal occult blood testing (FOBT) is simple, inexpensive, and proven effective at reducing mortality from CRC. Immunochemical fecal occult blood tests facilitate compliance and offer improved specificity, but at increased cost in comparison to FOBT. Fecal DNA testing may provide enhanced sensitivity for detection of CRC in comparison with FOBT, but its high cost limits its use for generalized screening. Rectal mucin testing requires additional evaluation to determine its sensitivity and specificity in comparison with guaiac-based FOBT. Serum tests, such as proteomics, nuclear matrix proteins, and serum DNA, are still in their infancy, but remain a hope for the future.

Colorectal cancer screening: prospects for molecular stool analysis

Colorectal cancer is common. As many patients present with advanced disease, an effective screening test would have substantial clinical benefits. Recent progress in understanding the biology of colorectal cancer (and of cancer cells in general) has led to possible new approaches to screening. In particular, there are prospects of developing tests based on analysis of stool, which promise improved accuracy, safety, affordability and patient compliance.

A Simulation Model for Colorectal Cancer Screening: Potential of Stool Tests with Various Performance Characteristics Compared with Screening Colonoscopy

OBJECTIVE

Many new stool tests intended to detect neoplastic cells or cell products are developed at present for colorectal cancer (CRC) screening. The aim of this study was to simulate a population-based screening setting to assess and compare the potential for early detection and prevention of CRC of screening based on stool tests with different sensitivity and specificity and of screening with colonoscopy as a primary screening tool.

METHOD

A Markov model was developed aimed to estimate the proportion of CRC cases which are early detected or prevented due to screening as well as the number of equired stool tests and colonoscopies per early detected or prevented CRC case. Model outcomes were calculated for the offer of annual stool testing from age 55 to 74 in combination with colonoscopic follow-up of positive test results and for the offer of screening colonoscopy as a primary screening tool at ages 55 and 65. The long-lasting risk reduction of colonoscopy allowing the removal of precancerous lesions was taken into account quantitatively.

RESULTS

For a variety of stool tests with different performance characteristics, the proportion of CRC cases early detected or prevented was estimated to be higher for stool testing in combination with colonoscopic follow-up of positive test results compared with screening colonoscopy assuming levels of compliance to be expected for the respective screening scheme. Optimizing performance characteristics of stool tests in terms of detecting precancerous lesions, in addition to those in terms of detecting CRC, seemed to be crucial for maximizing effectiveness of CRC screening with stool tests.

CONCLUSION

Screening based on new stool tests with colonoscopic follow-up of positive test results might offer a high potential for early detection or prevention of CRC.

Stool screening for colorectal cancer: molecular approaches

Assay of molecular markers in stool represents a promising noninvasive approach to screen colorectal cancer. Given that neoplasms exfoliate abundantly into the lumen and that DNA recovered from stool can be assayed with sensitive techniques, there is a strong biologic rationale to pursue this emerging technology. A challenge with DNA-based testing relates to the selection of markers. Because of the molecular heterogeneity of cancer, no single marker has yielded perfect sensitivity. Several combinations of markers in early stool assays have produced high detection rates of both colorectal cancer and advanced adenomas in selected patient groups, but observations from large representative populations are lacking at present. Potential expanded applications of stool DNA testing include detection of supracolonic aerodigestive cancers and of dysplasia in inflammatory bowel disease. Further marker discovery and technologic refinements should translate into improved test performance and fuel a continued evolution with this screening approach.

Stool decay-accelerating factor as a marker for monitoring the disease activity during leukocyte apheresis therapy in patients with refractory ulcerative colitis

BACKGROUND AND AIMS

We have shown previously that concentrations of stool decay-accelerating factor (DAF; CD55), a complement regulatory protein, in patients with ulcerative colitis (UC) are increased in relation to the severity of the colonic mucosal inflammation. In the present study, we evaluated the usefulness of stool DAF as a marker for monitoring disease activity in patients with steroid-resistant active UC being treated with leukocyte apheresis performed with a centrifugal cell separator.

METHODS

Twenty-one patients with active and steroid-resistant UC were treated with leukocyte apheresis once a week for 4 weeks, and stool DAF concentrations were determined weekly by immunoassay.

RESULTS

After treatment, 11 (52%) of the 21 UC patients went into remission. Stool DAF concentrations decreased promptly and steadily in the responsive group. The difference reached statistical significance as soon as after the second apheresis session (P < 0.003), compared with values before the therapy and corresponding values in the non-responsive group (P = 0.024). The reduction in stool DAF concentrations after the second apheresis session was significantly greater in the responsive group (median 90%, range 22-90%) than in the non-responsive group (median -13%, range -307-94%) (P = 0.008). Hematological tests, that is, white blood cell (WBC) count and C-reactive protein, declined significantly during the apheresis therapy, but not in relation to therapeutic response.

CONCLUSION

Stool DAF concentration is a useful marker in the clinical response of UC patients to treatment with leukocyte apheresis.

Increased serum concentrations and surface expression on peripheral white blood cells of decay-accelerating factor (cd55) in patients with active ulcerative colitis

Inflammatory stimuli induce expression and release of decay-accelerating factor (DAF), a complement-regulatory protein present on peripheral-blood cells. Therefore, in ulcerative colitis (UC), an inflammatory colonic disease in which activated leukocytes are involved, DAF may be released from leukocytes into the circulation. In this study we compared serum DAF concentrations and surface DAF expression on peripheral-blood cells in patients with UC with disease activity. Peripheral-blood samples were obtained from 60 patients with UC (30 with active and 30 with inactive disease) and 19 healthy volunteers. Serum DAF concentrations were determined by means of immunoassay, and surface DAF expression on blood cells was examined with the use of flow cytometry. Serum DAF concentrations in patients with active disease (mean 48.6 ng/mL) were significantly higher than those in patients whose disease was in remission (33.3 ng/mL; P =.0003) and those in healthy controls (32.3 ng/mL; P =.0007). Surface DAF expression on neutrophils, CD14+ monocytes, and subsets of lymphocytes in patients with active UC was significantly increased compared with that in patients with UC in remission and in healthy controls. The increased serum DAF concentrations and surface DAF expression on leukocyte fractions in patients with active disease fell to significantly lower levels when the disease had gone into remission after medical therapy. Serum DAF concentrations are increased in UC patients in relation to disease activity. The likely source of increased DAF concentrations is peripheral-blood leukocytes that have been activated as part of the UC disease process.