Limitations Of Colonoscopy Research Articles

Comparison between interval and sporadic colon cancer in terms of clinicopathologic and molecular features.

205 Background: Interval colon cancer occurs due to either limitations of colonoscopy or rapidly developing new tumors, possibly reflecting molecular and environmental differences in tumorigenesis. This study aimed to compare the clinicopathologic and molecular features of interval colon cancer with those of sporadic colon cancer in Asia. Methods: This prospective, multicenter, cross‐sectional study was conducted from May 2017 to December 2021 at six university hospitals in South Korea. Interval colon cancer was defined as colon cancer diagnosed within 5 years of complete colonoscopy. We compared the clinicopathologic and molecular biological characteristics, including CpG island methylator phenotype (CIMP), KRAS, BRAF, and microsatellite instability (MSI), between patients with interval and sporadic colon cancers. Results: We compared and analyzed 28 patients with interval colon cancer and 72 patients with sporadic cancer. There was no difference in terms of sex, BMI, underlying disease, and family history in the clinical comparison between the interval and sporadic cancer groups. There was no difference in the location, shape, or stage of cancer including metastasis, between the two groups. In molecular biological analysis, CIMP was 5.1% positive for sporadic cancer and 17.9% positive for interval colon cancer, indicating an approximately 13% greater frequency in interval colon cancer (p = .036). KRAR mutation was observed in 36.7% of patients with sporadic cancers and 17.9% of those with interval colon, which was about 18% higher in sporadic cancer, but there was no statistically significant difference (p = .066). There was no difference between MSI and BRAF genotype between the sporadic and interval cancer groups. Conclusions: Unlike the findings of western studies, there was no clinical difference between sporadic and interval colon cancer. In molecular biological comparison, the CIMP positivity rate was significantly higher in patients with interval colon cancer.

A145 ENDOSCOPICALLY NON-VISIBLE INTERVAL COLONIC ADENOCARCINOMA DESPITE HIGH-QUALITY SURVEILLANCE.

Abstract Background Colonoscopy remains the gold-standard for screening and surveillance of colorectal cancer (CRC). Regular colonoscopy with polypectomy has been associated with reduced CRC incidence and mortality. However, interval CRC, defined as cancer diagnosed between initial screening and subsequent surveillance colonoscopies, occurs at rates of 2–14%. Identified risk factors for interval cancers include patient-related factors (older age, diverticular disease, proximal CRC), endoscopy-related factors (colonoscopy by non-gastroenterologists or in an outpatient setting; endoscopists with low rates of completion, adenoma detection or polypectomy) and biologic factors (microsatellite instability (MSI), CpG island methylation). We report a patient with interval metastatic ileo-cecal adenocarcinoma despite multiple, high-quality surveillance colonoscopies, not endoscopically visible as no visible intra-luminal mucosal component was present. Aims To describe a case of an interval CRC without an endoscopically visible intra-luminal component. Methods Case description and literature review. Results A 69-year-old male, with a history of multiple advanced colonic polyps requiring multiple surveillance colonoscopies and polypectomies, presented with symptoms of bowel obstruction. An abdominal CT scan revealed findings of terminal ileitis and upstream small bowel obstruction. Colonoscopy was performed, revealing obstruction of the ileo-cecal valve with a firm cecal submucosal lesion without abnormal overlying mucosal abnormalities. Exploratory laparoscopy revealed a mass at the ileo-cecal valve with associated peritoneal deposits. A right hemicolectomy was performed, and pathological examination demonstrated metastatic invasive adenocarcinoma involving the cecum, the terminal ileum and ileo-cecal valve without extension into the lumen or formation of an overt polypoid mass. The tumour extended into the wall of the distal ileum in a circumferential fashion, involving the immediate deep serosa, but with only minimal, focal mucosal ileal involvement and no overt polypoid mass. An independent review of the case and resection specimen by a second pathologist confirmed absence of significant ileal or colonic mucosal involvement and no obstructing intraluminal component. Conclusions This case illustrates a rare presentation of an interval CRC that was not identified despite several high-quality surveillance colonoscopies, as only minimal mucosal involvement was present. As endoscopy remains the gold-standard for early detection and removal of pre-malignant lesions and early malignancy, the patient’s presentation with interval malignant bowel obstruction and metastatic disease, despite adequate quality surveillance, demonstrates an inherent limitation of colonoscopy. To our knowledge, this is only the third documented case of endoscopically non-visible interval CRC. Funding Agencies NoneNone

Advances in Colonoscopy

Colonoscopy with polypectomy has been established as the major prevention and detection strategy for colorectal cancer for over a decade. Over this period advances in colonoscopic imaging, polyp detection, prediction of histopathology and polypectomy techniques have all been seen; however, the true magnitude of the limitations of colonoscopy has only recently been widely recognized. The rate and location of missed or interval cancers after complete colonoscopy appears to be influenced by the operator-dependency of colonoscopy and failure of conventional practices to detect and treat adenomatous, and possibly more importantly, non-adenomatous colorectal cancer precursors. Consequently, studies that expand our understanding of these factors and advances that aim to improve colonoscopy, polypectomy, and cancer protection are of critical importance.

Colonoscopy Quality is the Answer for the Emerging Issue of Interval Cancer.

Colonoscopy is currently regarded as the gold standard and preferred screening method for colorectal cancer (CRC). Recently, however, a limitation of colonoscopy in the prevention of CRCs has been identified, particularly in the right-sided colon, and the problem of so-called interval cancers has emerged. The prevalence of interval cancer is estimated to be between 4% and 8% of CRCs detected. Although the exact etiology of interval cancer remains unknown, factors implicated in the development of interval cancers include missed lesions at the time of colonoscopy, incomplete resection of previous neoplastic lesions, different tumor biology, and serrated pathway of carcinogenesis. However, recent evidence suggests that interval cancers are related to the training of the endoscopist and quality of the colonoscopy rather than tumor biology. Therefore, the importance of adequate training and continuous monitoring of the colonoscopy quality, which are amenable to improvement, cannot be overstated in order to prevent the risk of interval cancers. In this study, the current literature regarding the prevalence and potential factors related to interval cancers and colonoscopy quality-related issues are reviewed.

Cancer Risks After Endometrial Cancer in Mismatch Repair Mutation Carriers

11%, 9%, and 11%, respectively, and the relative risks compared with the general population were significantly increased for each. Strengths of the study include the substantial patient population, of relatively unbiased source, the comprehensive approach to genetic diagnosis and cohort follow-up, and the experience of the investigators. The data on cancer incidence after endometrial cancer diagnosis are helpful but require attention to the details of surveillance, not all of which were available. Frequency of colonoscopy or other screening was based on questionnaires. Interventions to communicate HNPCC/LS screening guidelines or to otherwise foster cancer surveillance were not identified and were presumably heterogeneous. For these reasons, it is worth considering the aftermath of endometrial cancer diagnosis in the setting of HNPCC/LS. Unsurprisingly, a protective role for colonoscopy screening was seen. A linear reduction in freedom from colorectal cancer was found with increased interval of surveillance, from 44% in those having annual exam to 13% in those with exams at 4- to 5- year intervals. However, colorectal cancer did occur despite even annual surveillance. This phenomenon has been seen in more formal screening studies, underscoring the limitations of colonoscopy generally in assuring protection against colorectal cancer (9). More specifically, the subtlety of early lesions and their rapid growth to become interval cancer was very likely a factor, although unproven by the limited numbers. Consistent with other data, colorectal cancer risk was lower in MSH6 mutation carriers (standardized incidence ratios of 4.46 vs 38.7 and 58.5 for MLH1 and MSH2 mutation carriers, respectively). Despite this, no changes in screening guidelines have yet been recommended for MSH6 mutation carriers. Colorectal cancer risk could not be assessed for PMS2 mutation carriers because data were not collected for them. This group has been considered to be at lower risk of colorectal cancer (10). No data were available regarding screening for other at-risk organs. The modest increased risk of breast cancer was thought to have perhaps been an artifact of increased screening, but no actual screening data were brought to bear on this. Again, no enhancement of breast cancer screening has yet been recommended in HNPCC/LS.

ICES Report: New Findings about the Risks and Limitations of Colonoscopy Used in the Early Detection of Colorectal Cancer

Colonoscopy has established benefits for the detection and prevention of colorectal cancer, which is the second leading cause of cancer-related deaths in Canada and the United States. However, two recently published studies from scientists at the Institute for Clinical Evaluative Sciences (ICES) have found that the procedure has certain limitations (Baxter et al. 2009; Rabeneck et al. 2008). First, colonoscopy seems to be less effec-tive at preventing cancer deaths from tumours that originate in the right side of the large bowel. Second, while the procedure is safe for many patients, certain people appear to be at increased risk for serious complications. Colonoscopy is widely used to detect both colorectal cancer and adenomatous polyps, which may become malignant if left alone. During a complete colonoscopy, a physician - usually a gastroenterologist or general surgeon - inserts a long, flexible tube called a colonoscope through the patient's rectum and along the length of the large bowel. The goal is to scan the entire colon for potentially cancerous or pre-cancerous growths. If such a polyp or lesion is detected, it can often be removed during the colonoscopy so that no additional procedures or surgery are needed. The findings from the two new ICES studies, detailed below, are especially important given the widespread and increasing use of colonoscopy and the need to evaluate possible harms from and limitations of the procedure.

The inpatient Colonoscopy: A Difficult Endeavor

The performance of colonoscopy on patients admitted to hospital is a common occurrence. There are a variety of indications for inpatient colonoscopies ranging from acute gastrointestinal bleeding to iron deficiency anemia to occult blood positivity. The practice of colonoscopy for these patients has become relatively commonplace, with most physicians rapidly scheduling the procedure and, in fact, many booking the patient directly to the endoscopy unit and obtaining the full history and consent at the time of the procedure. This practice of inpatient colonoscopy clearly has some advantages with expedited assessment; however, there are a number of issues that limit the benefit of this procedure and may, in some cases, counterbalance the potential gain from the procedure. In the next two sections of ‘Ask the Expert’ we will present a ‘Pro and Con’ discussion for inpatient colonoscopy. In contradistinction to most ‘Pro/Con’ arguments, we have chosen to start with the limitations of colonoscopy in the setting of patients admitted to hospital. The opposing view will be presented in next month’s Journal. Dr Robert Enns There is a plethora of literature on inpatient colonoscopy that demonstrates benefit and safety (1–6). At first glance, it seems that colonoscopy is something that should be offered routinely to inpatients without hesitation. Although the benefit has been demonstrated in many studies, most of these have concerned themselves with acute gastrointestinal bleeding. There are a number of reasons why the physician should hesitate before proceeding with an urgent colonoscopy.

Colonoscopic polypectomy: A critical review of recent literature

Colonoscopic polypectomy continues to be a major activity of gastrointestinal endoscopists, based upon the belief that ridding the colon of polyps prevents colon cancer. We review recent literature bearing on this assumption, emphasizing the benefits and limitations of colonoscopy for screening and surveillance of polyps. CT colonography has developed as an alternative or adjunct to colonoscopy but has not surpassed it in accuracy or therapeutic potential. Other recent technologic developments, such as magnification and chromoendoscopy, are reviewed, and an attempt is made to put them in perspective.

Usefulness and limitations of colonoscopy in a proctological clinic.

Colonoscopy is a superior diagnostic tool for the detection of cancer of the colon. Its limitations include that it is not always available and there is a great deal of discomfort for the patient. It should therefore be used as effectively as possible. The goal of this retrolective cohort study was to analyze the usefulness of colonoscopy, especially by relating it to the subsequent therapeutic impact. Indication-related groups included "rectal bleeding," "other symptoms suggestive of malignancy," and "follow-up." In 714 patients selected as a result of admission to the proctological unit of our surgical clinic, a carcinoma was discovered in 9% and an adenoma in 13.4%. Patients with rectal bleeding were found to benefit most from colonoscopy since active therapeutic management followed in 56% of the cases. On comparison, there was a direct therapeutic impact in only 10% of the colonoscopies performed for follow-up. Identification of additional factors such as mucosal proliferation markers may help to improve the efficiency of endoscopy by more specifically designating the populations at risk for colonic neoplasia.

Colonoscopic Diagnosis of Inflammatory Bowel Disease

The indications and limitations of colonoscopy in the diagnosis of inflammatory bowel disease are well defined. The endoscopic examination is usually easily performed and well tolerated by the patient, but, since endoscopic examination of the colon is an invasive procedure (and potentially dangerous), colonoscopy should only be performed in those patients in whom the indication is clear and the benefits identifiable. Colonoscopy may provide valuable information in the diagnosis and may help outline the course of therapy in patients with inflammatory bowel disease.

Limitations and complications of colonoscopy

Limitations and complications of colonoscopy