Optimizing Colorectal Cancer Screening

Colorectal cancer (CRC) screening is a rapidly moving field. This thesis provides strategies and insights that may contribute to optimizing CRC screening. The main topics of the thesis are introduced in part I which gives an overview of the burden of CRC worldwide and the initiatives to reduce this burden. Part II further focusses on fecal occult blood test-based CRC screening. The main two fecal occult blood tests are the guaiac-based fecal occult blood test (gFOBT) and the more recently developed fecal immunochemical test (FIT). The diagnostic accuracy of FIT and gFOBT in average-risk individuals is compared in a meta-analysis. The subsequent chapters explore various aspects of FIT screening and optimization of FIT screening strategies. We focus on age differences, cut-off, the use of two FITS per screening round instead of one, and the predictive value of a negative FIT in subsequent screening rounds. Part III of the thesis provides more insight in factors that are associated with quality in CRC screening, surveillance and colonoscopy. The accuracy, quality, and readability of online information on CRC screening and surveillance is evaluated. Also, quality indicators for colonoscopy are obtained from different hospitals and the effect of plenary feedback on variation in quality of colonoscopy is assessed. Furthermore, adherence to recommended surveillance intervals following removal of adenomas is evaluated. Finally, part IV discusses the main findings and insights obtained from our research projects and gives directions for future research

Advances in Fecal Tests for Colorectal Cancer Screening

textabstractColorectal 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

Awareness of Postpolypectomy Surveillance Guidelines: A Nationwide Survey of Colonoscopists in Canada

INTRODUCTION: Due to the increasing demand for colonoscopy, adherence to postpolypectomy surveillance guidelines is important. Suboptimal compliance can lead to unnecessary risks and ineffective use of resources. OBJECTIVE: To determine the awareness of and adherence to postpolypectomy surveillance guidelines among members of the Canadian Association of Gastroenterology (CAG). METHODS: A survey describing 14 clinical cases was mailed to all physician members (n=411) of the CAG. Respondents were required to recommend a surveillance interval and a reason for his or her choice. RESULTS: A total of 150 colonoscopists (37%) completed the survey. Adherence to the guidelines varied from 23% to 96% per clinical scenario (median 63%). Recommended surveillance intervals were too short in 0% to 60% of the different cases (median 8%). The recommended interval was most often (60%) too short for a patient with one tubular adenoma with high-grade dysplasia. Surveillance intervals were too long in 4% to 75% of the cases (median 9%). The recommended interval was most often too long in a patient with a villous adenoma 15 mm in size and removed piecemeal (75%). Most often, recommendations were reported to be based on guidelines (median 74%; range 31% to 94%). However, in nine of 14 cases, more than 10% (median 18%; range 12% to 38%) of the respondents stated that their recommendation was based on guidelines, but did not provide the appropriate surveillance interval. CONCLUSIONS: Compliance to colonoscopy surveillance guidelines is suboptimal and reflects both overuse and underuse. The results show that awareness about the content of guidelines needs to be raised and strategies implemented to increase adherence

A Randomized Controlled Trial of Four Precolonoscopy Bowel Cleansing Regimens

BACKGROUND: The ideal bowel cleansing regimen for colonoscopy has yet to be determined. OBJECTIVE: To compare the cleansing efficacy, and patient tolerability and safety of four bowel preparation regimens. METHODS: A total of 834 patients undergoing outpatient colonoscopy were randomly assigned to one of four regimens: 4 L polyethylene glycol (PEG); 2 L PEG + 20 mg bisacodyl; 90 mL of sodium phosphate (NaP); or two sachets of a commercially available bowel cleansing solution (PSMC) + 300 mL of magnesium citrate (M). The primary outcome measure was cleansing efficacy, which was scored by blinded endoscopists using the Ottawa Bowel Preparation Scale. Secondary outcome measures were bowel preparation quality according to time of colonoscopy, and patient tolerability and safety. RESULTS: The mean total cleansing score was significantly worse in the NaP group compared with the other three groups (P<0.0001). The mean cleansing scores were worse in patients who underwent morning versus afternoon colonoscopy, a finding that was consistent in all four groups. PSMC + M was the best tolerated regimen. No clinically significant mean changes in creatinine or electrolyte levels were identified, although a significantly higher proportion of patients in the NaP group developed hypokelemia (P<0.0001). CONCLUSIONS: 2 L PEG + 20 mg bisacodyl, or PSMC + M was as efficacious as 4 L PEG and superior to NaP for bowel cleansing. A short interval between the completion of bowel preparation and the start of colonoscopy (ie, ‘runway time’), irrespective of bowel preparation regimen, appeared to be a more important predictor of bowel cleanliness than the cathartic agents used

Awareness of Postpolypectomy Surveillance Guidelines: A Nationwide Survey of Colonoscopists in Canada

Several studies have demonstrated that screening asymptomatic, average-risk individuals and those at increased risk can reduce colorectal cancer mortality. Adherence to postpolypectomy surveillance guidelines becomes increasingly important amid the increasing demands for colonoscopy because suboptimal compliance can lead to unnecessary risks and the ineffective use of resources. However, performing too many surveillance colonoscopies, or at intervals that are too short, may hinder access to endoscopic procedures and decrease the cost effectiveness of colorectal cancer screening programs. Two reasons appear to be primarily responsible for nonadherence to postpolypectomy guidelines: lack of awareness or familiarity, and disagreement with the guidelines. Accordingly, this study aimed to determine the awareness of postpolypectomy guidelines among members of the Canadian Association of Gastroenterology, and the factors associated with physicians’ choices to deviate from them