Circulating tumour markers can define patients with normal colons, benign polyps, and cancers

Abstract

Background:Early diagnosis represents the best opportunity for cure of colorectal cancer. Current screening programmes use faecal occult blood testing for screening, which has limited sensitivity and poor specificity.Methods:In this study we looked at a series of previously described diagnostic markers utilising circulating free DNA (cfDNA), with a preparation method allowing small DNA fragments to be isolated. The Circulating free DNA was isolated from samples obtained from 85 patients, including 35 patients without endoscopic abnormality, a group of 26 patients with benign colorectal adenomas, and 24 patients with colorectal carcinomas. In each case, polymerase chain reaction (PCR) was performed for Line1 79 bp, Line1 300 bp, Alu 115 bp, Alu 247 bp, and mitochondrial primers. In addition, carcinoembryonic antigen (CEA) was measured by ELISA. Each marker was analysed between normal, polyp, and cancer populations, and the best performing analysed in combination by logistic regression.Results:The best model was able to discriminate normal from populations with adenoma or carcinoma using three DNA markers and CEA, showing an area under the receiver operator characteristic (ROC) curve of 0.855 with a positive predictive value of 81.1% for polyps and cancer diagnosis.Conclusion:These circulating markers in combination with other markers offer the prospect of a simple blood test as a possible secondary screen for colorectal cancers and polyps in patients with positive faecal occult blood tests.

Methodological, biological and clinical aspects of circulating free DNA in metastatic colorectal cancer

“…In general, the levels are higher in mCRC patients than in healthy controls, as shown in Table 1 [15,20,47,58,[63][64][65][66][67][68][69][70][71][72]; and the levels have some correlation to stage as reported in a limited number of studies [15,41,68,73] in primary CRC. These findings give important biological information, and researchers suggest that cfDNA has potential as a diagnostic or screening tool; a potential that is currently being investigated by several groups.…”

Next generation sequencing techniques in liquid biopsy: focus on non-small cell lung cancer patients

“…In addition, their multiplexing power is restricted, limiting the simultaneous analysis of additional emerging biomarkers. These limitations may be overcome by next generation sequencing (NGS), which enables the sequencing of large genomic regions or several exons on ctDNA (7)(8)(9). However, the requirement in this setting of a high degree of sensitivity may easily lead to false positive results, which underlines the need of a careful validation of a number of critical points, including blood collection, cfDNA extraction, library preparation, sequencing and variant calling (Figure 1).…”

“…In most clinical trials, EDTA containing tubes (Vacutainer) were used for blood collection (4)(5)(6)(7)(8)(9). This approach avoids clotting and allows obtaining the plasma sample, Is particularly important, after the blood collection, to proceed with plasma preparation by centrifugation within 1 h, as ctDNA is associated with a high turn-over (15 min half-life).…”

“…In particular, whole blood has multiple sources that can be used for nucleic acid purification, including ctDNA (4)(5)(6). This represents a small fraction (<0.5%) of the total cfDNA passively released into the blood through necrosis or apoptosis of tumor cells or actively released by primary cancer cells or circulating tumor cells (CTCs) (4)(5)(6)(7)(8)(9). Many clinical trials have intensively investigated the role of EGFR mutational assessment on ctDNA in NSCLC patients as an alternative to tumor tissue procurement; most of the data have been generated in patients in progressive disease to detect resistance mutations (e.g., T790M) (4-13).…”

926 KRas Mutation Analysis by PCR – Comparison of Two Methods

“…The understanding of colorectal cancer (CRC) biology is rapidly growing and several molecular pathways including Wnt-β-catenin, TGF-β and epidermal growth factor receptor (EGFR) signalling have been identified that are deregulated at different stages of colon carcinogenesis [2,3]. Genetic alterations in CRC show promise as potential biomarkers for early cancer diagnosis as well as in selection of patients for treatment [4][5][6][7][8]. In recent years targeted therapies inhibiting EGFR signalling have been introduced into clinical practice resulting in improvement of overall survival of a subset of patients with advanced metastatic disease.…”