Screening For Colorectal Neoplasia Research Articles

Use of faecal markers in screening for colorectal neoplasia: a European group on tumor markers position paper

Several randomized controlled trials have shown that population-based screening using faecal occult blood testing (FOBT) can reduce mortality from colorectal neoplasia. Based on this evidence, a number of countries have introduced screening for colorectal cancer (CRC) and high-risk adenoma and many others are considering its introduction. The aim of this article is to critically review the current status of faecal markers as population-based screening tests for these neoplasia. Most of the available faecal tests involve the measurement of either occult blood or a panel of DNA markers. Occult blood may be measured using either the guaiac faecal occult blood test (gFOBT) or a faecal immunochemical test (iFOBT). Although iFOBT may require a greater initial investment, they have several advantages over gFOBT, including greater analytical sensitivity and specificity. Their use results in improved clinical performance and higher uptake rates. Importantly for population screening, some of the iFOBTs can be automated and provide an adjustable cutoff for faecal haemoglobin concentration. However, samples for iFOBT, may be less stable after collection than for gFOBT. For new centres undertaking FOBT for colorectal neoplasia, the European Group on Tumour Markers recommends use of a quantitative iFOBT with an adjustable cutoff point and high throughput analysis. All participants with positive FOBT results should be offered colonoscopy. The panel recommends further research into increasing the stability of iFOBT and the development of improved and affordable DNA and proteomic-based tests, which reduce current false negative rates, simplify sample transport and enable automated analysis.

Early Detection and Screening for Colorectal Neoplasia: Making Sense of the Guidelines

Each year, approximately 1 million new cases of colorectal cancer (CRC) occur worldwide, with substantial morbidity and mortality. For colon cancer in the United States, 147,000 new cases and 50,000 colon cancer-related deaths have been estimated for the coming year. The long natural history of colorectal neoplasia affords the opportunity to improve survival from this disease through preventive measures. Currently, screening for adenomatous polyps and early-stage cancers provides the best opportunity to improve survival. Growing knowledge of CRC pathogenesis and its natural history is allowing the development of new tools to identify those who will benefit most from colon cancer screening and is defining proper surveillance intervals. Recently, guidelines for screening for colorectal neoplasia were revised substantially by several organizations, based on developing technologies and a growing body of data regarding the efficacy of CRC screening.

Fecal MicroRNAs as Novel Biomarkers for Colon Cancer Screening

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths, but currently available noninvasive screening programs have achieved only a modest decrease in mortality. MicroRNAs (miRNA) play an important role in a wide array of biological processes and are commonly dysregulated in neoplasia. We aimed to evaluate the feasibility of fecal miRNAs as biomarkers for colorectal neoplasia screening. Total RNA was extracted from freshly collected stool samples from 8 healthy volunteers and 29 samples collected via fecal occult blood testing from subjects with normal colonoscopies, colon adenomas, and CRCs. miRNA expression analyses were done with TaqMan quantitative reverse transcription-PCR for a subset of miRNAs. Illumina miRNA microarray profiling was done to evaluate the differences in expression patterns between normal colonic mucosa tissues and stool samples from healthy subjects. We efficiently extracted miRNAs from stool specimens using our developed protocol. Data from independent experiments showed high reproducibility for miRNA extraction and expression. miRNA expression patterns were similar in stool specimens among healthy volunteers, and reproducible in stool samples that were collected serially in time from the same individuals. miRNA expression profiles from 29 patients showed higher expression of miR-21 and miR-106a in patients with adenomas and CRCs compared with individuals free of colorectal neoplasia. Our data indicate that miRNAs could be extracted from stool easily and reproducibly. The stools of patients with colorectal neoplasms have unique and identifiable patterns of miRNA expression. Fecal miRNAs may be an excellent candidate for the development of a noninvasive screening test for colorectal neoplasms.

S1593: Effects of Indication for Colonoscopy and Time Since Previous Colonoscopy on Adenoma Detection Rates Using the Third Eye Retroscope

Colonoscopy is the preferred screening for colorectal neoplasia in the United States as it reduces colorectal cancer incidence, but lesions can be missed. Interval neoplasia is detected in a small number of patients who have had a recent colonoscopy mostly due to incomplete colon examinations, presence of lesions difficult to visualize with the colonoscope, or neoplastic biologic factors that stimulate tumor growth. The Third Eye® Retroscope® (TER) (Avantis Medical Systems, Inc., Sunnyvale, CA) is a disposable device that provides a retrograde view complementing the forward view of the colonoscope during withdrawal.

A Comparison of the Diagnostic Performance of Guaiac and Immunochemical Fecal Occult Blood Tests with Colonoscopy for the Detection of Colorectal Neoplasia

Purpose: While screening for colorectal neoplasia using fecal occult blood tests (FOBTs) has demonstrated a reduction in colorectal cancer morbidity and mortality, consensus has not been reached as to the best FOBT to use in large scale population screening initiatives. Our aim was to compare the diagnostic performance characteristics of the guaiac-based (G-FOBT) Hemoccult II® (Beckman Coulter) and two fecal immunochemical tests (I-FOBT); the Hemoccult ICT® (Beckman Coulter) and MagStream HemSp® (Fujirebio) relative to colonoscopy. Methods: We used a prospective observational cohort design. 1000 asymptomatic individuals were recruited from the wait lists of 20 urban gastroenterology practices in Edmonton, Canada. Both average risk (50-75 years of age) and moderate risk patients (based on family history of colon cancer or previous history of colonic polyps) were recruited from April 2008 to May 2009. At least 1 month prior to the colonoscopy by expert colonoscopists, all subjects attended an educational session and collected three fecal occult blood tests from the same stool at home on 2 consecutive days. No dietary modifications were required. Laboratory technicians and colonoscopists were blinded to results of colonoscopy and FOBT respectively. Results: 1000 patients have been recruited into the study. Results are presented for the first 751 cases. (53.4% female, mean age 56). With colonoscopy, the adenoma detection rate was 24.7%, the advanced adenoma detection rate was 5.7% and the cancer detection rate was 0.3%. The performance characteristics of the 3 occult blood tests were compared relative to the colonoscopic findings as found in Table 1.Table 1: Sensitivity and specificity of G-FOBT and I-FOBTs for colorectal neoplasiaConclusion: Compared to G-FOBT, the I-FOBT tests were more sensitive for colonic advanced adenomas and cancers with a reasonable trade-off in specificity.

Noninvasive Screening for Colorectal Neoplasia: Does the Choice of Test Matter?

Noninvasive Screening for Colorectal Neoplasia: Does the Choice of Test Matter?

Increase in Serrated Polyp Detection Rate Over Time in a Cohort of Average Risk Patients Undergoing Screening Colonoscopy

Purpose: Serrated polyps represent precursor lesions in an alternative pathway to colorectal cancer which may account for 15% of all colorectal cancers diagnosed in the United States. Premalignant serrated polyps are frequently flat or sessile, subtle, located in the proximal colon and may be overlooked during colonoscopy. Awareness of the association of such lesions with risk for carcinoma has become generally known only in recent years. The aim of this study was to determine if the detection rate of serrated polyps in an average risk screening population has increased over time. Methods: Endoscopy and pathology reports were reviewed from all patients undergoing average risk colorectal neoplasia screening colonoscopies at Boston Medical Center from 2006 through 2008. Polyps were classified as adenoma (including tubular adenoma, tubulovillous and villous adenoma), serrated polyp (including hyperplastic polyp, serrated adenoma and sessile serrated adenoma), normal mucosa, or other. Polyp detection was summarized with count statistics and reported as rate per 100 screening colonoscopies. Differences in polyp distribution were assessed with the χ2 test for trends in proportions with α set to 0.05 and two-sided P values. All analyses were performed with the R Language and Environment for Statistical Computing version 2.9.0. Results: Included in the study were specimens of 4805 polypoid lesions from 8739 average risk screening colonoscopies. The rate of polyp detection per 100 screening colonoscopies was 24.0 (95% CI 23.2 to 24.7) for adenomas and 16.4 (95% CI 15.7 to 17.0) for serrated polyps. The detection rate of proximal serrated polyps, proximal sessile serrated adenomas, and both proximal and distal adenomas increased from 2006 to 2008 (Table). The difference in serrated polyp detection rates by year appeared to be mainly attributable to increased detection of proximal sessile serrated adenomas.Table: Table. Rate of detected polyps per 100 colonoscopies by year and locationConclusion: This study describes the detection rate of colorectal polyps in average risk screening colonoscopies at an urban academic medical center over a recent 3 year period. Practice personnel and technology were constant over this time. There was a statistically significant increase in the detection rate of proximal serrated polyps and both proximal and distal adenomas over the period. Increased awareness of the clinical significance of flat and sessile lesions including proximal hyperplastic polyps and sessile serrated adenomas may account in part for these findings.

A simple image processing approach for electronic cleansing in computed tomographic colonography

The prevalence of colon cancer has seen strong demand in screening for colorectal neoplasia, and this has drawn considerable attention to the technological advances in Computed Tomographic Colonography (CTC). With the assistance of an oral contrast agent, an imaging technique known as Electronic Cleansing (EC), can affect virtual cleaning of the computed tomography (CT) images, to remove fecal material that is tagged by the agent. Technical problems can arise with electronic cleansing however, when the air lumen causes distortions to the tagged regions which result in partial volume effects.Combining the simple image arithmetic of an electronic cleansing algorithm, with a vertical motion filter at the fluid level of the bowel, artifacts such as those caused by an air lumen are eliminated. Essentially, the filter becomes a vector for that carries the measurement of vertical motion to neutralise the artifact that is causing partial volume effects. Results demonstrate that despite its simplicity, this technique offers accuracy and is able to successfully maintain the normal intra-colonic structure, while supporting digital leaning of tagged residual material appearing on the colon wall.

Early Detection of and Screening for Colorectal Neoplasia

There are approximately one million new cases of colorectal cancer (CRC) per year worldwide, with substantial associated morbidity and mortality. The long natural history of colorectal neoplasia affords the opportunity to use preventive measures to improve survival in this disease. Currently screening for adenomatous polyps and early-stage cancers is the best methodology for improving survival. The increasing knowledge of CRC pathogenesis and its natural history is allowing the development of new tools to identify patients who will benefit most from colon cancer screening and the defining of appropriate surveillance intervals. The guidelines for screening for colorectal neoplasia have recently been substantially revised by several organizations based on developing technologies and a growing body of data on the efficacy of CRC screening.

Detectability of colorectal neoplastic lesions using a narrow‐band imaging system: A pilot study

Flat and depressed colorectal neoplastic lesions can be difficult to identify using conventional colonoscopy techniques. Narrow-band imaging (NBI) provides unique views especially of mucosal vascular network and helps in visualization of neoplasia by improving contrast. The aim of this study was to assess the feasibility of using NBI for colorectal neoplasia screening. Forty-seven consecutive patients, who underwent high definition colonoscopy (HDC) screening examinations revealing neoplastic lesions, were enrolled in our prospective study. No biopsies or resections were performed during the initial HDC, but patients in whom lesions were detected underwent further colonoscopies using NBI, with the results of the first examination blinded from the colonoscopist. They then received appropriate treatment. We compared diagnostic detection rates of neoplastic lesions for HDC and NBI procedures using total number of all identified neoplastic lesions as reference standard. Altogether, 153 lesions were detected and analyzed in 43 patients. Mean diagnostic extubation times were not significantly different (P = 0.18), but the total number of lesions detected by NBI was higher (134 vs 116; P = 0.02). Based on macroscopic type, flat lesions were identified more often by NBI (P = 0.04). As for lesion size, only flat lesions < 5 mm were detected more frequently (P = 0.046). Lesions in the right colon were identified more often by NBI (P = 0.02), but NBI missed two flat lesions >or= 10 mm located there. Narrow band imaging colonoscopy may represent a significant improvement in the detection of flat and diminutive lesions, but a future multi-center controlled trial should be conducted to fully evaluate efficacy for screening colonoscopies.

Stool DNA and Occult Blood Testing to Screen for Colorectal Neoplasia

Stool DNA and Occult Blood Testing to Screen for Colorectal Neoplasia

Asia Pacific consensus recommendations for colorectal cancer screening

Colorectal cancer (CRC) is rapidly increasing in Asia, but screening guidelines are lacking. Through reviewing the literature and regional data, and using the modified Delphi process, the Asia Pacific Working...

Performance of a Previously Validated CT Colonography Computer-Aided Detection System in a New Patient Population

A computer-aided detection (CAD) system with high sensitivity in the detection of adenomatous polyps in varied CT colonography (CTC) data sets increases the utility of CAD in the clinical setting. The purpose of this study was to evaluate the standalone performance of an existing CAD system with a new set of CTC data from screening patients at an institution and geographic location different from those at which the CAD system was trained. CTC data were collected from the records of 104 patients undergoing screening for colorectal neoplasia. Most of the patients were at average risk, had CTC findings suggestive of polyps, and underwent colonoscopy. Patients underwent cathartic bowel preparation, were given an oral contrast agent, and underwent imaging in the prone and supine positions. The patients had 86 adenomas confirmed at same-day optical colonoscopy; 47 of these tumors were 10 mm in diameter or larger, and 39 measured 6-9 mm. The CTC data were analyzed with an existing CAD system for colonography that was trained with previously acquired data. In a previous non-polyp-enriched screening cohort, the standalone performance of the CAD system was 93.3% (28/30) sensitivity for adenomatous polyps 10 mm or larger, 51.1% (47/92) sensitivity for adenomas 6-9 mm, and a mean false-positive rate of 8.6 per patient. Sensitivity comparisons were made with findings in the previous study. The CAD system had per-polyp sensitivities of 91.5% (43/47; 95% CI, 78.7-97.2%; p = 1.0) for adenomas 10 mm or larger and 82.1% (32/39; 65.9-91.9%; p = 0.0009) for adenomas 6-9 mm. The per-patient sensitivities were 97.6% (40/41; 85.6-99.9%; p = 0.6) for patients with adenomas 10 mm or larger and 82.4% (28/34; 64.8-92.6%; p = 0.047) for patients with adenomas 6-9 mm. The mean and median false-positive rates were 9.6 +/- 9.6 and 7.0 per patient, respectively. Common reasons for CAD misses (false-negative findings) were the presence of adherent contrast medium, flat adenomas, and adenomas located on or adjacent to normal colonic folds. In a random sample, 72.5% (29/40) of false-positive findings were attributable to folds or residual feces. The CAD system evaluated has a high level of performance in the detection of adenomatous polyps with CTC data from a polyp-enriched cohort different from that used to train the system.

Screening and surveillance for colorectal neoplasia: uncertainties of colonoscopic management

Over the past decade the use of screening and surveillance modalities has been associated with a small but significant decrease in the incidence of colorectal cancer and an increase in curability of lesions that are found. Although consensus-based international guidelines have stressed the variety of possible diagnostic options that can serve this purpose, in many countries colonoscopy withremoval of all polyps has become the test of choice. The evidence-base for this choice is largely derivative rather than direct and prospective, and many uncertainties remain in its use as a primary screening modality. This review examines our current guidelines relative to risk stratifying the populations offered the test; the onset, interval, and discontinuation of testing; and the important role of operator variability in outcome.

Screening for Colorectal Neoplasia in Those Undergoing Evaluation for Solid Organ Transplantation: Does It Alter the Clinical Management?

Screening for Colorectal Neoplasia in Those Undergoing Evaluation for Solid Organ Transplantation: Does It Alter the Clinical Management?

753 Stool DNA Screening of Colorectal Neoplasia: Improved Adenoma Detection By Novel Digital Melt Curve Assay

753 Stool DNA Screening of Colorectal Neoplasia: Improved Adenoma Detection By Novel Digital Melt Curve Assay

As tests evolve and costs of cancer care rise: reappraising stool‐based screening for colorectal neoplasia

Colorectal cancer screening and treatment are rapidly evolving. Aims To reappraise stool-based colorectal cancer screening in light of changing test performance characteristics, lower test cost and increasing colorectal cancer care costs. Using a Markov model, we compared faecal DNA testing every 3 years, annual faecal occult blood testing or immunochemical testing, and colonoscopy every 10 years. In the base case, faecal occult blood testing and faecal immunochemical testing gained life-years/person and cost less than no screening. Faecal DNA testing version 1.1 at $300 (the current PreGen Plus test) gained 5323 life-years/100 000 persons at $16 900/life-year gained and faecal DNA testing version 2 (enhanced test) gained 5795 life-years/100 000 persons at $15 700/life-year gained vs. no screening. In the base case and most sensitivity analyses, faecal occult blood testing and faecal immunochemical testing were preferred to faecal DNA testing. Faecal DNA testing version 2 cost $100 000/life-year gained vs. faecal immunochemical testing when per-cycle adherence with faecal immunochemical testing was 22%. Faecal immunochemical testing with excellent adherence was superior to colonoscopy every 10 years. As novel biological therapies increase colorectal cancer treatment costs, faecal occult blood testing and faecal immunochemical testing could become cost-saving. The cost-effectiveness of faecal DNA testing compared with no screening has improved, but faecal occult blood testing and faecal immunochemical testing are preferred to faecal DNA testing when patient adherence is high. Faecal immunochemical testing may be comparable to colonoscopy every 10 years in persons adhering to yearly testing.

Q&A on diagnosis, screening and follow-up of colorectal neoplasia

The impressive and brisk evolution of medical science prevents many physicians from a thorough update on all the research fields. Colorectal cancer diagnosis, screening and follow-up is well known to require a multi-disciplinary approach, as it is faced by several specialties such as primary care physicians, gastroenterologists, non-gastroenterologist internists, radiologists and surgeons. To address this issue in a mutual perspective, we focused on the main points of the epidemiology, diagnosis, screening and follow-up of colorectal neoplasia by using a simple “Question & Answers” structure.

Virtual vs. optical colonoscopy in symptomatic gastroenterology out‐patients: the case for virtual imaging followed by targeted diagnostic or therapeutic colonoscopy1

To compare virtual colonoscopy with optical colonoscopy findings in symptomatic patients. Computer tomographic colonography is an alternative to optical colonoscopy. Studies have shown that two-dimensional computer tomographic colonography does not have sufficient sensitivity. Three-dimensional computerized tomographic virtual colonoscopy compares well with optical colonoscopy for colorectal neoplasia screening in asymptomatic individuals. One hundred patients aged 50 and older underwent same day virtual colonoscopy and optical colonoscopy. The endoscopists were unaware of the radiologist's report until the withdrawal phase of the endoscopy when segmental unblinding occurred. The virtual colonoscopy and optical colonoscopy findings were compared by using the unblinded optical colonoscopy as the reference standard. Pancolonic endoluminal virtual colonoscopy was achieved in 99 patients. Optical colonoscopy caecal intubation occurred in 91 patients. Direct comparison was possible in 90 patients. Both techniques revealed the three cancers detected. Virtual colonoscopy revealed 11 polyps > or = 6 mm diameter in nine patients. Optical colonoscopy revealed 10 polyps > or = 6 mm diameter in nine patients with a further 15-mm polyp discovered after segmental unblinding. In symptomatic patients, three-dimensional virtual colonoscopy is equivalent to optical colonoscopy for diagnosing colon cancer and clinically significant polyps. A case can be made for three-dimensional virtual colonoscopy as a primary modality followed if necessary by same day-targeted optical colonoscopy.

Colonoscopy: The Dominant and Preferred Colorectal Cancer Screening Strategy in the United States

Colonoscopy: The Dominant and Preferred Colorectal Cancer Screening Strategy in the United States