Second-Look Colonoscopies and the Impact on Capacity in FIT-Based Colorectal Cancer Screening

New insights into colorectal cancer screening and early detection tests

Colorectal cancer (CRC) is a common cancer in both men and women worldwide. Creating a diagnostic panel is necessary for early diagnosis which could lead to a better long-term survival in cancer patients. Colonoscopy every 10 years, starting at age 50, is the preferred CRC screening test. Many studies have been worked on potential diagnostic biomarkers of CRC. In this article, we described the recent evolutions in the development of CRC noninvasive screening assays. Recently, a multifunctional fecal DNA test has been available commercially in the USA. A few other US FDA-approved tests like Epi proColon® (Epigenomics AG, Berlin, Germany) are also available now. Although a new marker class for fecal occult blood test, a novel biomarker based on fecal bacteria in CRC patients and circulating tumor cells are under investigation, there is still a strong need to do more research for CRC screening strategies.

Long-Term Prediction of the Demand of Colonoscopies Generated by a Population-Based Colorectal Cancer Screening Program

OBJECTIVE

To estimate the long-term need for colonoscopies after a positive fecal immunochemical test (FIT) and post-polypectomy surveillance in the context of a population-based colorectal cancer (CRC) screening program.

METHODS

A discrete-event simulation model was built to reproduce the process of CRC screening and post-polypectomy surveillance following European guidelines in a population of 100,000 men and women aged 50-69 years over a 20-year period. Screening consisted of biennial FIT and colonoscopy in participants with positive results. The model was mainly fed using data from the first and second rounds of a Spanish program (2010-2013). Data on post-polypectomy surveillance results were obtained from the literature. A probabilistic multivariate sensitivity analysis was performed on the effect of participation, FIT positivity, and adherence to surveillance colonoscopies. The main outcome variables were the number of colonoscopies after a positive FIT, surveillance colonoscopies, and the overall number of colonoscopies.

RESULTS

An average yearly number of 1,200 colonoscopies after a positive FIT were predicted per 100,000 inhabitants with a slight increase to 1,400 at the end of the 20-year period. Surveillance colonoscopies increased to an average of 1,000 per 100,000 inhabitants in the long-term, showing certain stabilization in the last years of the 20-year simulation horizon. The results were highly sensitive to FIT positivity.

CONCLUSIONS

Implementing a population-based CRC screening program will increase the demand for colonoscopies, which is expected to double in 20 years, mainly due to an increase in surveillance colonoscopies.

Accrediting for screening-related colonoscopy services: What is required of the endoscopist and of the endoscopy service?

Colorectal cancer (CRC) screening is widely implemented to reduce CRC incidence and related mortality. The impact of screening as well as the balance between screening burden and benefits strongly depends on the quality of colonoscopy. Besides quality, safety of the endoscopic procedure and patient satisfaction are important outcome parameters for a screening program. Therefore the requirements for both CRC screening endoscopy services and endoscopists focus on technical aspects, patient safety, and patient experience. Stringent quality assurance by means of routine monitoring of quality indicators for the performance of endoscopists and endoscopy units is recommended. This allows setting minimum standards, targeted interventions, and enhancement of the overall quality of population screening. This reviews deals with guidelines and quality standards for colorectal cancer screening, with focus on both endoscopist and endoscopy services.

Advances in Fecal Tests for Colorectal Cancer Screening

Colorectal cancer (CRC) forms an important public health problem, especially in developed countries. CRC screening tests can be used to identify asymptomatic individuals with CRC precursors and (early) cancer. Removal of these lesions reduces CRC incidence and prevents CRC-related mortality. There are a range of screening tests available, each with advantages and disadvantages. Stool screening tests can broadly be divided into fecal occult blood tests (FOBTs) and molecular biomarker test, such as DNA/RNA marker tests, protein markers, and fecal microbiome marker tests. Guaiac fecal occult blood tests (gFOBT) have been demonstrated in large randomized screening trials to reduce CRC mortality. Fecal immunochemical tests (FIT) have superior adherence, usability, and accuracy as compared to gFOBT. Advantage of the use of quantitative FITs in CRC screening programs is the cut-off level that can be adjusted. Molecular biomarker DNA tests have shown to detect significantly more cancers than FIT. By combining biomarker DNA tests with FIT, sensitivity for advanced adenomas can be increased significantly. However, it has lower specificity thus demands more colonoscopy resources, is more cumbersome, and costly. The adherence has not been assessed in population screening trials. For these reasons, FIT is therefore at present regarded as the preferred method of non-invasive CRC screening. This chapter will review the current status of fecal test-based CRC screening.

Stool DNA methylation assays in colorectal cancer screening

Colorectal cancer (CRC) is fourth most common cancer in men and third in women worldwide. Developing a diagnostic panel of sensitive and specific biomarkers for the early detection of CRC is recognised as to be crucial for early initial diagnosis, which in turn leads to better long term survival. Most of the research on novel potential CRC biomarkers in the last 2 decades has been focussed on stool DNA analysis. In this paper, we describe the recent advances in non-invasive CRC screening and more specifically in molecular assays for aberrantly methylated BMP3 and NDRG4 promoter regions. In several research papers these markers showed superior rates for sensitivity and specificity in comparison to previously described assays. These tests detected the majority of adenomas ≥ 1 cm in size and the detection rates progressively increased with larger adenomas. The methylation status of the BMP3 and NDRG4 promoters demonstrated effective detection of neoplasms at all sites throughout the colon and was not affected by common clinical variables. Recently, a multitarget stool DNA test consisting of molecular assays for aberrantly methylated BMP3 and NDRG4 promoter regions, mutant KRAS and immunochemical assay for human haemoglobin has been made commercially available and is currently reimbursed in the United States. Although this is the most sensitive non-invasive CRC screening test, there is the need for further research in several areas - establishment of the best timeframe for repeated DNA stool testing; validation of the results in populations outside of North America; usefulness for surveillance and prognosis of patients; cost-effectiveness of DNA stool testing in real-life populations.