A comparison of the immunochemical fecal occult blood test and total colonoscopy in the asymptomatic population

A systematic evaluation of stool DNA preparation protocols for colorectal cancer screening via analysis of DNA methylation biomarkers

Objectives

Colorectal cancer (CRC) screening using stool samples is now in routine use where tumor DNA methylation analysis for leading markers such as NDRG4 and SDC2 is an integral part of the test. However, processing stool samples for reproducible and efficient extraction of human genomic DNA remains a bottleneck for further research into better biomarkers and assays.

Methods

We systematically evaluated several factors involved in the processing of stool samples and extraction of DNA. These factors include: stool processing (solid and homogenized samples), preparation of DNA from supernatant and pellets, and DNA extraction with column and magnetic beads-based methods. Furthermore, SDC2 and NDRG4 methylation levels were used to evaluate the clinical performance of the optimal protocol.

Results

The yield of total and human genomic DNA (hgDNA) was not reproducible when solid stool scraping is used, possibly due to sampling variations. More reproducible results were obtained from homogenized stool samples. Magnetic beads-based DNA extraction using the supernatant from the homogenized stool was chosen for further analysis due to better reproducibility, higher hgDNA yield, lower non-hgDNA background, and the potential for automation. With this protocol, a combination of SDC2 and NDRG4 methylation signals with a linear regression model achieved a sensitivity and specificity of 81.82 and 93.75%, respectively.

Conclusions

Through the systematic evaluation of different stool processing and DNA extraction methods, we established a reproducible protocol for analyzing tumor DNA methylation markers in stool samples for colorectal cancer screening.

Quantitative immunochemical fecal occult blood test for neoplasia in colon cancer screening

OBJECTIVE

To investigate the performance of the quantitative immunochemical fecal occult blood test (qFIT) and to determine the association between the fecal hemoglobin (Hb) level and the location and size of adenomas and the stages of colorectal cancer (CRC).

METHODS

A total of 692 participants were included in the study. Their fecal Hb level was measured using an OC-SENSA MICRO qFIT. The colonoscopy results, including the location, size, and histological features of the adenomas, as well as the relationship between the Hb level and different characteristics were analyzed. Performance of the qFIT at various thresholds of fecal Hb levels was evaluated.

RESULTS

Advanced colorectal neoplasia (ACRN) was identified in 76 patients based on the colonoscopic and pathological examinations. Large adenomas (≥10 mm) had a higher fecal Hb level than small adenomas (<10 mm). Advanced adenomas located on the left side of the colon presented with a higher fecal Hb level than those on the right side (P = 0.022). Stage III-IV CRC patients had a significantly higher Hb level than stage I-II patients (P = 0.013). The sensitivity and specificity of qFIT for ACRN was 51.3% and 86.4%，respectively, with the best cut-off level of 400 ng/mL. The sensitivity and specificity for CRC was 61.0% and 89.1%, with the best cut-off level of 500 ng/mL.

CONCLUSIONS

qFIT has an acceptable sensitivity and specificity for ACRN detection. Furthermore, the qFIT results are associated with the location and size of adenomas as well as the grade of CRC.

Diagnostic Value of Methylated Septin9 for Colorectal Cancer Detection

Background

Methylated Septin9 (mSEPT9) has been suggested as a reliable biomarker in colorectal cancer (CRC) detection. We aimed to determine the diagnostic value of mSEPT9 for CRC detection in Chinese patients. In addition, we compared the diagnostic efficacy of mSEPT9 to traditional screening method [fecal occult blood test (FOBT)] and two biomarkers [carcinoembryonic antigen (CEA) and carbohydrate antigen-199 (Ca-199)].

Methods

Overall 248 subjects including 123 patients with CRC and 125 controls were included. Plasma and fecal samples were collected for CEA, Ca-199, mSEPT9, and FOBT tests. Sensitivity and specificity were calculated to evaluate the diagnostic efficacy of each method; receiver operating characteristic (ROC) curve was plotted for the assessment of diagnostic accuracy, and comparisons among FOBT, mSEPT9, and the combination were assessed through area under the ROC curve (AUC).

Results

mSEPT9 achieved overall sensitivity and specificity of 61.8% [95% confidence interval (CI): 53.0–69.9%] and 89.6% (83.0–93.8%), respectively, with an AUC value of 0.757 (95% CI: 0.701–0.807), superior to FOBT [sensitivity: 61.4% (50.9–70.9%); specificity: 70.3% (59.1–79.5%); AUC: 0.658 (0.578–0.723)], CEA [sensitivity: 35.0% (27.1–43.7%); specificity: 62.6% (53.8–70.7%); AUC: 0.485 (0.411–0.559)], and Ca-199 [sensitivity: 17.9% (12.1–25.6%); specificity: 55.7% (48.9–64.1%); AUC: 0.353 (0.283–0.423)]. The combination of mSEPT9 and FOBT further improved sensitivity and AUC value of 84.1% (75.1–90.3%) and 0.807 (0.752–0.863), respectively, while specificity was declined to 62.2% (50.8–72.4%).

Conclusion

mSEPT9 demonstrated best diagnostic ability in CRC detection compared with FOBT, CEA, and Ca-199. The combination of mSEPT9 and FOBT further improved diagnostic sensitivity especially for early stage disease, which may provide a new approach for future CRC screening, though further investigations are warranted.

Current noninvasive tests for colorectal cancer screening: An overview of colorectal cancer screening tests

Colorectal cancer (CRC) has become the third most common cancer in the world. Screening has been shown to be an effective way to identify early CRC and precancerous lesions, and to reduce its morbidity and mortality. Several types of noninvasive tests have been developed for CRC screening, including the fecal occult blood test (FOBT), the fecal immunochemical test (FIT), the fecal-based DNA test and the blood-based DNA test (the SEPT9 assay). FIT has replaced FOBT and become the major screening test due to high sensitivity, specificity and low costs. The fecal DNA test exhibited higher sensitivity than FIT but its current cost is high for a screening assay. The SEPT9 assay showed good compliance while its performance in screening needs further improvements. These tests exhibited distinct sensitivity and specificity in screening for CRC and adenoma. This article will focus on the performance of the current noninvasive in vitro diagnostic tests that have been used for CRC screening. The merits and drawbacks for these screening methods will also be compared regarding the techniques, usage and costs. We hope this review can provide suggestions for both the public and clinicians in choosing the appropriate method for CRC screening.

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.).

Competition in Colon Cancer Screening? What Is the Role of Colonoscopy?

BACKGROUND

Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the Western world. The incidence could be reduced if this cancer were to be diagnosed at an early stage of disease. A competition has started between the existing screening methods to be the most efficient in detecting premalignant conditions. This review illustrates the current state of screening techniques for CRC.

METHOD

Pubmed was searched for meta-analyses and prospective studies on screening for CRC, with an emphasis on colonography, computed tomographic colonography (CTC), magnetic resonance colonography (MRC), stool DNA testing, and colon capsule endoscopy, and critical appraisal of the research was done by the reviewers.

RESULTS

The imaging techniques (CTC and MRC) had similar detection rates for bigger lesions (≥10 mm) as colonoscopy. High-definition colonoscopy showed better efficiency with smaller lesions. The techniques developing around colonoscopy such as the retro-viewing colonoscope, the balloon colonoscope, or the 330-degree viewing colonoscope try to enhance efficacy by reducing the adenoma miss rate in right-sided, non-polypoid lesions. Colon capsule endoscopy and the stool detection systems are limited to identifying cancer but not necessarily adenomas.

CONCLUSION

Colonoscopy is the preferred CRC screening strategy and the undisputed gold standard in terms of efficacy.

Fecal immunochemical test accuracy in average-risk colorectal cancer screening

AIM: To assess the fecal immunochemical test (FIT) accuracy for colorectal cancer (CRC) and advanced neoplasia (AN) detection in CRC screening.

METHODS: We performed a multicentric, prospective, double blind study of diagnostic tests on asymptomatic average-risk individuals submitted to screening colonoscopy. Two stool samples were collected and the fecal hemoglobin concentration was determined in the first sample (FIT1) and the highest level of both samples (FITmax) using the OC-sensor™. Areas under the curve (AUC) for CRC and AN were calculated. The best FIT1 and FITmax cut-off values for CRC were determined. At this threshold, number needed to scope (NNS) to detect a CRC and an AN and the cost per lesion detected were calculated.

RESULTS: About 779 individuals were included. An AN was found in 97 (12.5%) individuals: a CRC in 5 (0.6%) and an advanced adenoma (≥ 10 mm, villous histology or high grade dysplasia) in 92 (11.9%) subjects. For CRC diagnosis, FIT1 AUC was 0.96 (95%CI: 0.95-0.98) and FITmax AUC was 0.95 (95%CI: 0.93-0.97). For AN, FIT1 and FITmax AUC were similar (0.72, 95%CI: 0.66-0.78 vs 0.73, 95%CI: 0.68-0.79, respectively, P = 0.34). Depending on the number of determinations and the positivity threshold cut-off used sensitivity for AN detection ranged between 28% and 42% and specificity between 91% and 97%. At the best cut-off point for CRC detection (115 ng/mL), the NNS to detect a CRC were 10.2 and 15.8; and the cost per CRC was 1814€ and 2985€ on FIT1 and FITmax strategies respectively. At this threshold the sensitivity, NNS and cost per AN detected were 30%, 1.76, and 306€, in FIT1 strategy, and 36%, 2.26€ and 426€, in FITmax strategy, respectively.

CONCLUSION: Performing two tests does not improve diagnostic accuracy, but increases cost and NNS to detect a lesion.

[Colorectal cancer screening programme in France, role of the National Institute of Cancer]

With almost 37,500 new cases per year and 17,000 deaths, colorectal cancer represents a major public health problem in France. A new stage in the fight against this cancer should be marked in 2009 with the widespread implementation of the colorectal cancer screening programme over the whole of the French territory. This population-based screening programme targets an eligible population of 16 million persons. The evaluation of the first 23 pilot districts allowed a standardization of the main quality and efficacy indicators. The implementation of the colorectal cancer screening programme relies on monitoring centres, usually one per district, set up for the national breast cancer screening programme. The programme refers to quality assurance guidelines and includes explicit policy with specified age categories, method, and interval for screening. A national screening training programme for newly districts joining the programme was implemented. A small number of laboratories have been selected for the programme on quality criteria. The French National Cancer Institute contributes to organization, information, guidelines, and research. The replacement of the guaiac test used in the French programme by an immunochemical test should be effective in the next few years.