Prevalence of nonpolypoid colorectal neoplasia: an Italian multicenter observational study

Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2024

1:  ESGE recommends cold snare polypectomy (CSP), to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of diminutive polyps (≤ 5 mm).Strong recommendation, high quality of evidence. 2:  ESGE recommends against the use of cold biopsy forceps excision because of its high rate of incomplete resection.Strong recommendation, moderate quality of evidence. 3:  ESGE recommends CSP, to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of small polyps (6-9 mm).Strong recommendation, high quality of evidence. 4:  ESGE recommends hot snare polypectomy for the removal of nonpedunculated adenomatous polyps of 10-19 mm in size.Strong recommendation, high quality of evidence. 5:  ESGE recommends conventional (diathermy-based) endoscopic mucosal resection (EMR) for large (≥ 20 mm) nonpedunculated adenomatous polyps (LNPCPs).Strong recommendation, high quality of evidence. 6:  ESGE suggests that underwater EMR can be considered an alternative to conventional hot EMR for the treatment of adenomatous LNPCPs.Weak recommendation, moderate quality of evidence. 7:  Endoscopic submucosal dissection (ESD) may also be suggested as an alternative for removal of LNPCPs of ≥ 20 mm in selected cases and in high-volume centers.Weak recommendation, low quality evidence. 8:  ESGE recommends that, after piecemeal EMR of LNPCPs by hot snare, the resection margins should be treated by thermal ablation using snare-tip soft coagulation to prevent adenoma recurrence.Strong recommendation, high quality of evidence. 9:  ESGE recommends (piecemeal) cold snare polypectomy or cold EMR for SSLs of all sizes without suspected dysplasia.Strong recommendation, moderate quality of evidence. 10:  ESGE recommends prophylactic endoscopic clip closure of the mucosal defect after EMR of LNPCPs in the right colon to reduce to reduce the risk of delayed bleeding.Strong recommendation, high quality of evidence. 11:  ESGE recommends that en bloc resection techniques, such as en bloc EMR, ESD, endoscopic intermuscular dissection, endoscopic full-thickness resection, or surgery should be the techniques of choice in cases with suspected superficial invasive carcinoma, which otherwise cannot be removed en bloc by standard polypectomy or EMR.Strong recommendation, moderate quality of evidence.

Efficacy of international web-based educational intervention in the detection of high-risk flat and depressed colorectal lesions higher (CATCH project) with a video: Randomized trial

OBJECTIVES

Three subcategories of high-risk flat and depressed lesions (FDLs), laterally spreading tumors non-granular type (LST-NG), depressed lesions, and large sessile serrated lesions (SSLs), are highly attributable to post-colonoscopy colorectal cancer (CRC). Efficient and organized educational programs on detecting high-risk FDLs are lacking. We aimed to explore whether a web-based educational intervention with training on FIND clues (fold deformation, intensive stool/mucus attachment, no vessel visibility, and demarcated reddish area) may improve the ability to detect high-risk FDLs.

METHODS

This was an international web-based randomized control trial that enrolled non-expert endoscopists in 13 Asian countries. The participants were randomized into either education or non-education group. All participants took the pre-test and post-test to read 60 endoscopic images (40 high-risk FDLs, five polypoid, 15 no lesions) and answered whether there was a lesion. Only the education group received a self-education program (video and training questions and answers) between the tests. The primary outcome was a detection rate of high-risk FDLs.

RESULTS

In total, 284 participants were randomized. After excluding non-responders, the final data analyses were based on 139 participants in the education group and 130 in the non-education group. The detection rate of high-risk FDLs in the education group significantly improved by 14.7% (66.6-81.3%) compared with -0.8% (70.8-70.0%) in the non-education group. Similarly, the detection rate of LST-NG, depressed lesions, and large SSLs significantly increased only in the education group by 12.7%, 12.0%, and 21.6%, respectively.

CONCLUSION

Short self-education focusing on detecting high-risk FDLs was effective for Asian non-expert endoscopists. (UMIN000042348).

Quality indicators in colonoscopy: the chasm between ideal and reality

Continuous measurement of quality indicators (QIs) should be a routine part of colonoscopy, as a wide variation still exists in the performance and quality levels of colonoscopy in Korea. Among the many QIs of colonoscopy, the adenoma detection rate, average withdrawal time, bowel preparation adequacy, and cecal intubation rate should be monitored in daily clinical practice to improve the quality of the procedure. The adenoma detection rate is the best indicator of the quality of colonoscopy; however, it has many limitations for universal use in daily practice. With the development of natural language processing, the adenoma detection rate is expected to become more effective and useful. It is important that colonoscopists do not strictly and mechanically maintain an average withdrawal time of 6 minutes but instead perform careful colonoscopy to maximally expose the colonic mucosa with a withdrawal time of at least 6 minutes. To achieve adequate bowel preparation, documentation of bowel preparation with the Boston Bowel Preparation Scale (BBPS) should be a routine part of colonoscopy. When colonoscopists routinely followed the bowel preparation protocols, ≥85% of outpatient screening colonoscopies had a BBPS score of ≥6. In addition, the cecal intubation rate should be ≥95% of all screening colonoscopies. The first step in improving colonoscopy quality in Korea is to apply these key performance measurements in clinical practice.

Two histologic compartments in nonpolypoid conventional colon adenomas

Two intertwined compartments coexisting in nonpolypoid conventional (i.e. tubular or villous) adenomas are highlighted in this review: one built of dysplastic tissue on top and the other portraying crypts with irregular, corrupted shapes, albeit lined with normal epithelium, below. The latter compartment has remained unattended in the literature. Recently, however, the histologic characteristics of the nondysplastic compartment in nonpolypoid conventional adenomas were closely examined, and some of its biological attributes were unveiled. Studies with the proliferation marker ki67 showed that the crypts with irregular, corrupted shapes in the nondysplastic compartment displayed haphazardly distributed proliferating cell-domains. Given that the proliferating cells are generated by stem cells, the relocation of proliferating cell-domains in those crypts seems to be the result of a reorganization of the stem cells within the crypts. The abnormal distribution of proliferating cells, the finding of p53-upregulated cells, and of crypts in asymmetric fission suggest that the crypts in that compartment are histo-biologically altered, probably somatically mutated. This new information might contribute to unravel the riddle of crypto-histogenesis of nonpolypoid conventional adenomas of the colon. More research along these lines is necessary, before the biology of the crypts in the nondysplastic compartment can be fully translated into molecular terms.

Interobserver agreement of the Paris and simplified classifications of superficial colonic lesions: a Western study

Background and study aims  The Paris classification of superficial colonic lesions has been widely adopted, but a simplified description that subgroups the shape into pedunculated, sessile/flat and depressed lesions has been proposed recently. The aim of this study was to evaluate the accuracy and inter-rater agreement among 13 Western endoscopists for the two classification systems. Methods  Seventy video clips of superficial colonic lesions were classified according to the two classifications, and their size estimated. The interobserver agreement for each classification was assessed using both Cohen k and AC1 statistics. Accuracy was taken as the concordance between the standard morphology definition and that made by participants. Sensitivity analyses investigated agreement between trainees (T) and staff members (SM), simple or mixed lesions, distinct lesion phenotypes, and for laterally spreading tumors (LSTs). Results  Overall, the interobserver agreement for the Paris classification was substantial (κ = 0.61; AC1 = 0.66), with 79.3 % accuracy. Between SM and T, the values were superimposable. For size estimation, the agreement was 0.48 by the κ-value, and 0.50 by AC1. For single or mixed lesions, κ-values were 0.60 and 0.43, respectively; corresponding AC1 values were 0.68 and 0.57. Evaluating the several different polyp subtypes separately, agreement differed significantly when analyzed by the k-statistics (0.08-0.12) or the AC1 statistics (0.59-0.71). Analyses of LSTs provided a κ-value of 0.50 and an AC1 score of 0.62, with 77.6 % accuracy. The simplified classification outperformed the Paris classification: κ = 0.68, AC1 = 0.82, accuracy = 91.6 %. Conclusions  Agreement is often measured with Cohen's κ, but we documented higher levels of agreement when analyzed with the AC1 statistic. The level of agreement was substantial for the Paris classification, and almost perfect for the simplified system.

Multicentre randomised controlled trial comparing standard and high resolution optical technologies in colorectal cancer screening

BACKGROUND AND OBJECTIVES

The UK bowel cancer screening programme (BCSP) has been established for the early detection of colorectal cancer offering colonoscopy to patients screened positive by faecal occult blood tests. In this multisite, prospective, randomised controlled trial, we aimed to compare the performance of Standard Definition Olympus Lucera (SD-OL) with Scope Guide and the High Definition Pentax HiLine (HD-PHL).

PATIENTS AND METHODS

Subjects undergoing a colonoscopy as part of the UK National BCSP at four UK sites were randomised to an endoscopy list run using either SD-OL or HD-PHL. Primary endpoints were polyp and adenoma detection rate (PDR and ADR, respectively) as well as polyp size, morphology and histology characteristics.

RESULTS

262 subjects (168 males, mean age 66.3±4.3 years) were colonoscoped (133 patients with HD-PHL while 129 with SD-OL). PDR and ADR were comparable within the two optical systems. The HD-PHL group resulted in a PDR 55.6% and ADR 43.6%; the SD-OL group had PDR 56.6% and ADR 45.7%. HD-PHL was significantly superior to SD-OL in detection of flat adenomas (18.6% vs 5.2%, p<0.001), but not detection of pedunculated or sessile polyps. Patient comfort, use of sedation and endoscopist perception of procedural difficulty resulted similar despite the use of Scope Guide with SD-OL.

CONCLUSION

PDR and ADR were not significantly different between devices. The high-resolution colonoscopy system HD-PHL may improve polyp detection as compared with standard resolution technology in detecting flat adenomas. This advantage may have clinically significant implications for missed lesion rates and post-colonoscopy interval colorectal cancer rates.

Metabolic syndrome is a risk factor for colorectal adenoma and cancer: a study in a White population using the harmonized criteria

BACKGROUND

Metabolic syndrome (MetS) has been associated with colorectal adenomas and cancer. However, MetS definitions have changed over time, leading to a heterogeneity of patients included in previous studies and a substantial inextensibility of observations across time or eastern and western populations. Our aim was to evaluate the association of 'harmonized' criteria-defined MetS and its individual components with colorectal neoplasia and cancer in a western population.

METHODS

In this multicenter, cross-sectional study, we prospectively evaluated consecutive outpatients who underwent open-access colonoscopy over a 3-month period. MetS was diagnosed according to the 2009 'harmonized' criteria.

RESULTS

Out of 5707 patients enrolled, we found 213 cancers (3.7%), 1614 polyps (28.3%), 240 nonpolypoid lesions (4.2%), 95 laterally spreading tumors (1.6%). Polyps presented histological low-grade dysplasia in 72.9% of samples, while in 9.8%, high-grade dysplasia or in situ carcinoma was present; dysplasia rates for nonpolypoid lesions were 66.2% (low-grade) and 2.9% (high-grade/in situ carcinoma), while for laterally spreading tumors, 29.6% and 37%, respectively. Overall, MetS prevalence was 41.6%. MetS correlated with both adenomas [odds ratio (OR): 1.76, 95% confidence interval (CI) 1.54-2.00] and cancer (OR: 1.92, 95% CI 1.42-2.58). MetS was the only risk factor for such colonic lesions in subjects younger than 50 years. For all colonic neoplasia, we found MetS and not its individual components to be significantly associated.

CONCLUSIONS

MetS is risk factor for cancer and adenoma in Whites, especially when younger than 50 years. MetS patients might be considered as a high-risk population also in colorectal cancer screening programs.

Risk factors associated with the detection and missed diagnosis of colorectal flat adenoma: a Chinese multicenter observational study

OBJECTIVES

Flat colorectal adenomas have a high risk of malignancy; however, their detection is often difficult due to their flat morphology. In this retrospective, large-scale study, we investigated the prevalence and characteristics of flat adenomas in a population in China.

METHODS

We analyzed the data collected for 16951 consecutive patients who underwent colonoscopy at four participating hospitals between September 2013 and September 2015. All colonoscopies were performed without magnification.

RESULTS

Among the 1,6951 patients, 2938 (17.3%) had adenoma and 796 (4.7%) had flat adenomas. The detection of flat adenoma showed a weak correlation with the detection of adenoma (r = 0.666). Multivariable logistic regression analysis revealed the following independent factors influencing the detection of flat adenomas: patient-related factors of age, presence of warning symptoms, history of adenomas and bowel preparation as well as endoscopist-related factors of endoscopist's level of proficiency, number of colonoscopy operators and withdrawal time.

CONCLUSIONS

The prevalence of flat adenomas in our study on Chinese patients was consistent with that reported from other countries. Factors conducive to the detection of flat adenomas were patient age of > 60 years, warning symptoms, history of adenoma, good bowel preparation, experienced endoscopist, single-operator colonoscopy and colonoscopy withdrawal time of >6 min.

Risk of Malignancy in Adenomas Detected During Screening Colonoscopy

BACKGROUND & AIMS

A higher incidence of proximal interval cancers after colonoscopy has been reported in several follow-up studies. One possible explanation for this might be that proximally located adenomas have greater malignant potential. The aim of the present study was to assess the risk of malignancy in proximal versus distal adenomas in patients included in a large screening colonoscopy database; adenoma shape and the patients' age and sex distribution were also analyzed.

METHODS

Data for 2007-2012 from the German National Screening Colonoscopy Registry, including 594,614 adenomas identified during 2,532,298 screening colonoscopies, were analyzed retrospectively. The main outcome measure was the rate of high-grade dysplasia (HGD) in adenomas, used as a surrogate marker for the risk of malignancy. Odds ratios (ORs) for the rate of HGD found in adenomas were analyzed in relation to patient- and adenoma-related factors using multivariate analysis.

RESULTS

HGD histology was noted in 20,873 adenomas (3.5%). Proximal adenoma locations were not associated with a higher HGD rate. The most significant risk factor for HGD was adenoma size (OR 10.36 ≥1 cm vs <1 cm), followed by patient age (OR 1.26 and 1.46 for age groups 65-74 and 75-84 vs 55-64 years) and sex (OR 1.15 male vs female). In comparison with flat adenomas as a reference lesion, sessile lesions had a similar HGD rate (OR 1.02) and pedunculated adenomas had a higher rate (OR 1.23). All associations were statistically significant (P ≤ .05).

CONCLUSIONS

In this large screening database, it was found that the rates of adenomas with HGD are similar in the proximal and distal colon. The presence of HGD as a risk marker alone does not explain higher rates of proximal interval colorectal cancer. We suggest that certain lesions (flat, serrated lesions) may be missed in the proximal colon and may acquire a more aggressive biology over time. A combination of endoscopy-related factors and biology may therefore account for higher rates of proximal versus distal interval colorectal cancer.

Radiologic Evaluation of Clinically Benign Rectal Neoplasms May Not Be Necessary Before Local Excision

BACKGROUND

Local excision may be curative for benign and malignant rectal neoplasms. Because many early rectal cancers are discovered incidentally after local excision of clinically benign lesions, it is unclear whether preoperative imaging with transrectal ultrasound or MRI affects management.

OBJECTIVE

The purpose of this study was to determine the diagnostic characteristics and effect of preoperative imaging on the incidence of malignancy in benign rectal lesions undergoing local excision.

DESIGN

Prospective data from 2 institutions were included. Coarsened exact matching created a balanced cohort comparing imaging and no-imaging groups.

SETTING

The study was conducted at high-volume specialist referral hospitals.

PATIENTS

Adult patients undergoing local excision via transanal endoscopic surgery between 1997 and 2016 for clinically benign rectal neoplasms were included.

INTERVENTION

The study intervention included preoperative imaging with transrectal ultrasound and/or MRI.

MAIN OUTCOME MEASURES

We measured the incidence of malignancy and diagnostic accuracy of preoperative imaging.

RESULTS

A total of 620 patients were included (272 with preoperative imaging and 348 without). There were 250 patients undergoing transrectal ultrasound, and 24 patients undergoing MRI (2 patients underwent both). Transrectal ultrasound and MRI correctly identified malignant polyps in 50% (11/22) and 44% (8/18). Overall agreement for benign versus malignant polyps between preoperative imaging and final pathology was κ = 0.30 (95% CI, 0.18-0.41) for transrectal ultrasound and 0.29 (95% CI, 0.01-0.57) for MRI. In both the overall and unmatched cohorts, the incidence of malignancy, margin involvement, and proportion of patients requiring salvage surgery was similar.

LIMITATIONS

Data were obtained from 2 institutions with different equipment over a long time period.

CONCLUSIONS

Preoperative imaging did not accurately identify malignancy in clinically benign rectal lesions and did not affect the incidence of malignancy, margin involvement, or proportion of patients requiring salvage surgery. Therefore, preoperative imaging may not be necessary for clinically benign lesions undergoing local excision. See Video Abstract at http://links.lww.com/DCR/A695.

Clinical Effectiveness of Submucosal Injection with Indigo Carmine Mixed Solution for Colon Endoscopic Mucosal Resection

BACKGROUND/AIMS

Submucosal injection with indigo carmine mixed solution can improve the delineation of colorectal neoplasia during endoscopic mucosal resection (EMR). Thus, the aim of this study was to evaluate the efficacy of submucosal injection with indigo carmine mixed solution during EMR of colorectal neoplasia.

METHODS

This was a prospective, randomized, controlled study of a total of 212 neoplastic colon polyps (5-20 mm) subjected to EMR in a single tertiary university hospital. The patients were randomized into two groups according to whether or not indigo carmine mixed solution was used, and the complete resection rate (CRR) after EMR was evaluated.

RESULTS

A total of 212 neoplastic polyps (normal saline group, 115; indigo carmine group, 97) were successfully removed by EMR. There was no significant difference in the CRR (92.8 vs. 89.6%, p = 0.414) or macroscopic delineation (86.0 vs. 93.8%, p = 0.118) between the two groups. In a separate analysis of sessile serrated adenomas/polyps (SSAs/Ps), macroscopic delineation was better in the indigo carmine group than the normal saline group (87.5 vs. 53.8%), albeit not significantly (p = 0.103). In univariate analyses, the CRR was significantly related to polyp location, polyp morphology, macroscopic delineation, and pathologic findings. In a multiple logistic regression analysis, macroscopic delineation (odds ratio (OR), 7.616, p = 0.001) and polyp pathology (OR, 8.621; p < 0.001) were significantly associated with the CRR.

CONCLUSIONS

Submucosal injection with indigo carmine mixed solution did not improve the CRR or macroscopic delineation of EMR of colorectal neoplasias.

Miss rate of colorectal neoplastic polyps and risk factors for missed polyps in consecutive colonoscopies

Background/Aims

Colonoscopic polypectomy is the best diagnostic and therapeutic tool to detect and prevent colorectal neoplasms. However, previous studies have reported that 17% to 28% of colorectal polyps are missed during colonoscopy. We investigated the miss rate of neoplastic polyps and the factors associated with missed polyps from quality-adjusted consecutive colonoscopies.

Methods

We reviewed the medical records of patients who were found to have colorectal polyps at a medical examination center of the Kangbuk Samsung Hospital between March 2012 and February 2013. Patients who were referred to a single tertiary academic medical center and underwent colonoscopic polypectomy on the same day were enrolled in our study. The odds ratios (ORs) associated with polyp-related and patient-related factors were evaluated using logistic regression analyses.

Results

A total of 463 patients and 1,294 neoplastic polyps were analyzed. The miss rates for adenomas, advanced adenomas, and carcinomas were 24.1% (312/1,294), 1.2% (15/1,294), and 0% (0/1,294), respectively. Flat/sessile-shaped adenomas (adjusted OR, 3.62; 95% confidence interval [CI], 2.40–5.46) and smaller adenomas (adjusted OR, 5.63; 95% CI, 2.84– 11.15 for ≤5 mm; adjusted OR, 3.18; 95% CI, 1.60–6.30 for 6–9 mm, respectively) were more frequently missed than pedunculated/sub-pedunculated adenomas and larger adenomas. In patients with 2 or more polyps compared with only one detected (adjusted OR, 2.37; 95% CI, 1.55–3.61 for 2–4 polyps; adjusted OR, 11.52; 95% CI, 4.61–28.79 for ≥5 polyps, respectively) during the first endoscopy, the risk of missing an additional polyp was significantly higher.

Conclusions

One-quarter of neoplastic polyps was missed during colonoscopy. We encourage endoscopists to detect smaller and flat or sessile polyps by using the optimal withdrawal technique.

Clinical utility of the SMSA grading tool for the management of colonic neoplastic lesions

BACKGROUND

Whilst polyp size has been traditionally used as a predictor of the complexity of endoscopic resection, the influence of other factors is increasingly recognised. The SMSA grading system takes into account polyp Site, Morphology, Size and Access, with higher scores correlating with increased technical difficulty.

AIMS

To evaluate whether the SMSA grading tool correlates with endoscopic and clinical outcomes.

METHODS

This retrospective study was conducted at two high volume centres in the United Kingdom and Italy. All polyps identified at colonoscopy were included in this study and classified as per the SMSA grading system.

RESULTS

A total of 1668 lesions were resected in 1016 patients. There was a positive correlation between increasing SMSA level and the inability to resect lesions "en bloc" (p<0.001). Histologically complete clearance was higher in the lower SMSA groups (p<0.0001). Additional endoscopic therapies, were more commonly required with the higher SMSA groups to achieve histological clearance (p<0.0001). Moreover, advanced histology in resection specimens and procedural complications were significantly less common in SMSA level 1 lesions compared to level 3 or 4 lesions (p<0.0001).

CONCLUSIONS

The SMSA grading tool is a useful predictor of outcome following the resection of colonic neoplastic lesions.

Patients With Nonpolypoid (Flat and Depressed) Colorectal Neoplasms at Increased Risk for Advanced Neoplasias, Compared With Patients With Polypoid Neoplasms

BACKGROUND & AIMS

Nonpolypoid colorectal neoplasms (NP-CRNs) are more likely to contain high-grade dysplasia or early-stage cancer than polypoid neoplasms. We aimed to determine the long-term outcomes of patients with at least 1 NP-CRN.

METHODS

We performed a longitudinal cohort study of 4454 patients at a Veterans' Affairs hospital who underwent colonoscopy from 2000 through 2005; 341 were found to have 1 or more NP-CRNs and were matched (3:1) with patients found to have 1 or more polypoid neoplasms (controls, n = 1025). We collected and analyzed data on baseline colonoscopy findings and first follow-up colonoscopy results through August 2014. We calculated the incidence of advanced neoplasia at first follow-up colonoscopy, as defined by the presence of ≥1 tubular or sessile serrated adenomas ≥10 mm in diameter, tubulovillous adenoma, high-grade dysplasia, or invasive cancer.

RESULTS

A significantly higher proportion of patients with 1 or more NP-CRNs (16.0%) were found to have advanced neoplasia at their first follow-up colonoscopy than controls (8.6%); the adjusted risk ratio was 1.6 (95% confidence interval, 1.05-2.6; P = .03). A significantly higher proportion of patients with 1 or more NP-CRNs were found to have additional NP-CRNs at the follow-up colonoscopy (17%) than controls (7%; relative risk, 2.3; 95% confidence interval, 1.5-3.5; P < .001). Similar proportions of patients in each group developed cancers after colonoscopy.

CONCLUSIONS

In a longitudinal cohort study, we found that patients with NP-CRN were more likely to develop additional NP-CRNs and to have advanced neoplasms at their first follow-up colonoscopy than patients with only polypoid neoplasms. However, patients with NP-CRN were not more likely to develop cancers after colonoscopy when surveillance guidelines were followed. Larger studies are needed to determine risk of colorectal cancer in patients with NP-CRN.

Risk of cancer in small and diminutive colorectal polyps

The prevalence of cancer in small and diminutive polyps is relevant to "resect and discard" and CT colonography reporting recommendations. We evaluated a prospectively collected colonoscopy polyp database to identify polyps <10mm and those with cancer or advanced histology (high-grade dysplasia or villous elements). Of 32,790 colonoscopies, 15,558 colonoscopies detected 42,630 polyps <10mm in size. A total of 4790 lesions were excluded as they were not conventional adenomas or serrated class lesions. There were 23,524 conventional adenomas <10mm of which 22,952 were tubular adenomas. There were 14,316 serrated class lesions of which 13,589 were hyperplastic polyps and the remainder were sessile serrated polyps. Of all conventional adenomas, 96 had high-grade dysplasia including 0.3% of adenomas ≤5mm in size and 0.8% of adenomas 6-9mm in size. Of all conventional adenomas, 2.1% of those ≤5mm in size and 5.6% of those 6-9mm in size were advanced. Among 36,107 polyps ≤5mm in size and 6523 polyps 6-9mm in size, there were no cancers. These results support the safety of resect and discard as well as current CT colonography reporting recommendations for small and diminutive polyps.

The Immune Landscapes of Polypoid and Nonpolypoid Precancerous Colorectal Lesions

Little is known about the immunoediting process in precancerous lesions. We explored this aspect of benign colorectal adenomas with a descriptive analysis of the immune pathways and immune cells whose regulation is linked to the morphology and size of these lesions. Two series of polypoid and nonpolypoid colorectal adenomas were used in this study: 1) 84 samples (42 lesions, each with matched samples of normal mucosa) whose gene expression data were used to quantify the tumor morphology- and size-related dysregulation of immune pathways collected in the Molecular Signature Database, using Gene Set Enrichment Analysis; 2) 40 other lesions examined with immunohistochemistry to quantify the presence of immune cells in the stromal compartment. In the analysis of transcriptomic data, 429 immune pathways displayed significant differential regulation in neoplasms of different morphology and size. Most pathways were significantly upregulated or downregulated in polypoid lesions versus nonpolypoid lesions (regardless of size). Differential pathway regulation associated with lesion size was observed only in polypoid neoplasms. These findings were mirrored by tissue immunostaining with CD4, CD8, FOXP3, MHC-I, CD68, and CD163 antibodies: stromal immune cell counts (mainly T lymphocytes and macrophages) were significantly higher in polypoid lesions. Certain markers displayed significant size-related differences regardless of lesion morphology. Multivariate analysis of variance showed that the marker panel clearly discriminated between precancerous lesions of different morphologies and sizes. Statistical analysis of immunostained cell counts fully support the results of the transcriptomic data analysis: the density of infiltration of most immune cells in the stroma of polypoid precancerous lesions was significantly higher than that observed in nonpolypoid lesions. Large neoplasms also have more immune cells in their stroma than small lesions. Immunoediting in precancerous colorectal tumors may vary with lesion morphology and stage of development, and this variability could influence a given lesion's trajectory to cancer.

CT Colonography: an update on current and future indications

Computed tomographic colonography (CTC) is a minimally invasive, patient-friendly, safe and robust colonic imaging modality. The technique is standardized and consolidated evidence from the literature shows that the diagnostic performances for the detection of colorectal cancer and large polyps are similar to colonoscopy (CS) and largely superior to alternative radiological exams, like barium enema. A clear understanding of the exact role of CTC will be beneficial to maximize the benefits and minimize the potential sources of frustration or disappointment for both referring clinicians and patients. Incomplete, failed, or unfeasible CS; investigation of elderly, and frail patients and assessment of diverticular disease are major indications supported by evidence-based data and agreed by the endoscopists. The use of CTC for symptomatic patients, colorectal cancer screening and colonic surveillance is still under debate and, thus, recommended only if CS is unfeasible or refused by patients.

Prevalence of advanced histological features and synchronous neoplasia in patients with flat adenomas

BACKGROUND AND AIMS

The prevalence of advanced histology in flat adenomas is uncertain. There are limited data on the prevalence of synchronous adenomas in patients with flat adenomas. The aims of this study were to determine whether the flat adenomas harbor advanced histology more than the polypoid adenomas and whether the presence of flat adenomas is an independent predictor of synchronous adenomas.

METHODS

A retrospective analysis of data from 3 prospective clinical trials conducted at 2 tertiary care referral centers that included patients undergoing screening or surveillance colonoscopy was performed. The location, size, and morphology of each polyp resected was documented and sent for histopathological examination in a unique specimen jar.

RESULTS

A total of 2931 polyps were removed in 1340 patients. Of the 1911 adenomas (65.2%), 293 (15.3%) were flat and 1618 (84.7%) were polypoid. The prevalence of advanced histology did not differ between flat and polypoid adenomas (1.4% vs 3.1%; P = .13). Multivariate analysis confirmed that the presence of at least 1 flat adenoma was a predictor of the presence of a large adenoma (P < .01; odds ratio [OR], 2.80; 95% CI, 1.86-4.22), advanced adenoma (P < .01; OR, 2.70; 95% CI, 1.80-4.06), and 3 or more adenomas (P < .01; OR, 2.44; 95% CI, 1.66-3.59).

CONCLUSION

Although the prevalence of advanced histology in flat adenomas is similar to that of polypoid adenomas, flat adenomas are associated with increased prevalence of synchronous large and advanced adenomas. Whether these results imply shorter surveillance intervals in patients with flat adenomas needs to be explored in future studies.

Disparities in prevalence, location, and shape characteristics of colorectal neoplasia between South Korean and U.S. patients

BACKGROUND

Colon cancer screening is being introduced in many countries, but standard Western screening approaches may not be appropriate for Asian societies if differences in colon cancer epidemiology exist. Comparative analysis of colorectal neoplasia patterns in South Korean and Western subjects has implications for appropriate screening approaches in non-Western societies.

METHODS

The results of concurrent screening colonoscopies performed in average-risk patients 50 to 69 years old in 2 teaching hospitals, Kyung Hee University Hospital (Seoul, South Korea) and Virginia Mason Medical Center (Seattle, Wash), were compared with respect to prevalence, histologic features, anatomic distribution, and shape characteristics of colorectal neoplasia.

RESULTS

The U.S. (n = 3460) and South Korean (n = 2193) cohorts were similar with regard to the prevalence of adenomas (28.5% vs 29.8%, respectively, P = .312) and advanced neoplasia (6.4% vs 5.4%, respectively, P = .102), but the proportion of proximal adenomas was greater in the U.S. cohort (62.8% vs 45.9%, P < .001). The prevalence of adenomas and advanced neoplasia was similar in male patients, but there was a greater prevalence of neoplasia (23.5% vs 18.8%, P = .006) and advanced neoplasia (5.1% vs 2.7%, P < .001) in U.S. women than South Korean women. When large (≥10 mm) adenomas were considered, proximal location and nonpolypoid (flat) shape were more common in the U.S. cohort (79.4% vs 37.1%, P = .003 and 43.5% vs 12.3%, P < .001, respectively). The overall prevalence of large flat adenomas in the U.S. cohort was 5 times that of the South Korean cohort (2.6% vs 0.5%, P < .001). Adjustment for sex ratio discrepancies (48.3% men in the U.S. cohort vs 60.8% in the South Korean cohort, P < .001) did not result in any significant changes in the conclusions.

CONCLUSION

Compared with Westerners, South Koreans have a more distal distribution of adenomas and advanced neoplasia and lower prevalence of large flat adenomas. South Korean women have a lower prevalence of colorectal neoplasia than Western women. Such disparities suggest that Western screening strategies cannot be directly adopted by other countries, but need to be customized by society.

Practice parameters for early colon cancer management: Italian Society of Colorectal Surgery (Società Italiana di Chirurgia Colo-Rettale; SICCR) guidelines

Early colon cancer (ECC) has been defined as a carcinoma with invasion limited to the submucosa regardless of lymph node status and according to the Royal College of Pathologists as TNM stage T1 NX M0. As the potential risk of lymph node metastasis ranges from 6 to 17% and the preoperative assessment of lymph node metastasis is not reliable, the management of ECC is still controversial, varying from endoscopic to radical resection. A meeting on recent advances on the management of colorectal polyps endorsed by the Italian Society of Colorectal Surgery (SICCR) took place in April 2014, in Genoa (Italy). Based on this material the SICCR decided to issue guidelines updating the evidence and to write a position statement paper in order to define the diagnostic and therapeutic strategy for ECC treatment in context of the Italian healthcare system.

Non-polypoid colorectal neoplasms: Classification, therapy and follow-up

In the last years, an increasing interest has been raised on non-polypoid colorectal tumors (NPT) and in particular on large flat neoplastic lesions beyond 10 mm tending to grow laterally, called laterally spreading tumors (LST). LSTs and large sessile polyps have a greater frequency of high-grade dysplasia and local invasiveness as compared to pedunculated lesions of the same size and usually represent a technical challenge for the endoscopist in terms of either diagnosis and resection. According to the Paris classification, NPTs are distinguished in slightly elevated (0-IIa, less than 2.5 mm), flat (0-IIb) or slightly depressed (0-IIc). NPTs are usually flat or slightly elevated and tend to spread laterally while in case of depressed lesions, cell proliferation growth progresses in depth in the colonic wall, thus leading to an increased risk of submucosal invasion (SMI) even for smaller neoplasms. NPTs may be frequently missed by inexperienced endoscopists, thus a careful training and precise assessment of all suspected mucosal areas should be performed. Chromoendoscopy or, if possible, narrow-band imaging technique should be considered for the estimation of SMI risk of NPTs, and the characterization of pit pattern and vascular pattern may be useful to predict the risk of SMI and, therefore, to guide the therapeutic decision. Lesions suitable to endoscopic resection are those confined to the mucosa (or superficial layer of submucosa in selected cases) whereas deeper invasion makes endoscopic therapy infeasible. Endoscopic mucosal resection (EMR, piecemeal for LSTs > 20 mm, en bloc for smaller neoplasms) remains the first-line therapy for NPTs, whereas endoscopic submucosal dissection in high-volume centers or surgery should be considered for large LSTs for which en bloc resection is mandatory and cannot be achieved by means of EMR. After piecemeal EMR, follow-up colonoscopy should be performed at 3 mo to assess resection completeness. In case of en bloc resection, surveillance colonoscopy should be scheduled at 3 years for adenomatous lesions ≥ 1 cm, or in presence of villous features or high-grade dysplasia patients (regardless of the size), while less intensive surveillance (colonoscopy at 5-10 years) is needed in case of single (or two) NPT < 1 cm presenting tubular features or low-grade dysplasia at histology.

Chromocolonoscopy

Chromoendoscopy techniques improve the visualization of mucosal structures. This article reviews and summarizes key studies addressing the impact of chromoendoscopy on colonic neoplasia detection and differentiation of neoplastic from non-neoplastic polyps in average and high-risk populations, including patients with colonic inflammatory bowel disease (IBD). In this context, there are convincing data that chromoendoscopy differentiates neoplastic from non-neoplastic polyps in average-risk populations with high accuracy. Moreover, dye-based chromoendoscopy improves neoplasia detection in colonic IBD surveillance.

The big picture: does colonoscopy work?

Colonoscopy for average-risk colorectal cancer screening has transformed the practice of gastrointestinal medicine in the United States. However, although the dominant screening strategy, its use is not supported by randomized controlled trials. Observational data do support a protective effect of colonoscopy and polypectomy on colorectal cancer incidence and mortality, but the level of protection in the proximal colon is variable and operator-dependent. Colonoscopy by high-level detectors remains highly effective, and ongoing quality improvement initiatives should consider regulatory factors that motivate changes in physician behavior.

Prevalence of non-polypoid colorectal neoplasms in southern Brazil

BACKGROUND AND AIM

Several studies suggest that non-polypoid lesions (NPL) show higher aggressiveness than polypoid lesions, particularly depressed lesions. The present study aimed to assess the prevalence of NPL and the presence of advanced histology in a Brazilian population.

METHODS

Two thousand and sixty-seven superficial neoplastic lesions diagnosed in 1135 patients were analyzed. Lesions were classified as polypoid and non-polypoid (flat and depressed) types, and evaluated for site, size, and histology (adenoma with grade of dysplasia, or early cancer).

RESULTS

Prevalence of NPL was 46.5%. NPL predominated in the right colon (62.9%), whereas polypoid lesions were detected mainly in the left colon (53.2%) (P < 0.001). NPL had a 34% higher probability of occurring in the right colon than polypoid lesions (P < 0.001). NPL were smaller than polypoid lesions (P = 0.03). There were 208 lesions >10 mm, of which 40 (19.2%) had advanced histology: 13% (18/138) of polypoid lesions; 27.3% (18/66) of flat lesions; and 100% (4/4) of depressed lesions (P < 0.001). Among 1859 neoplasms ≤10 mm, only 18 (1%) had advanced histology, and 15 of them were depressed lesions (P < 0.001). Advanced histology was more commonly detected in NPL than in polypoid lesions (P = 0.007), with significant difference in size (P < 0.001). NPL showed more advanced histology than polypoid lesions (OR 2.06; P = 0.01), especially depressed lesions (OR 36.35; P < 0.001). Among all neoplasms, the prevalence of depressed lesions was 2.2%.

CONCLUSION

NPL showed high prevalence and higher aggressiveness than polypoid lesions, especially the depressed type.

Colonoscopy: the current king of the hill in the USA

Colonoscopy is the dominant colorectal cancer screening strategy in the USA. There are no randomized controlled trials completed of screening colonoscopy, but multiple lines of evidence establish that colonoscopy reduces colorectal cancer incidence in both the proximal and distal colon. Colonoscopy is highly operator dependent, but systematic efforts to measure and improve quality are impacting performance. Colonoscopy holds a substantial advantage over other strategies for detection of serrated lesions, and a recent case-control study suggests that once-only colonoscopy or colonoscopy at 20-year intervals, by a high-level detector, could ensure lifetime protection from colorectal cancer for many patients.

Ileocaecal junction carcinoma: a clinicopathological study of 199 cases

AIM

The ileocaecal junction (ICJ) region is an epithelial transition zone in which carcinomas are frequently diagnosed. However, it is currently unknown whether ICJ carcinomas (ICJ-CAs) have distinctive features. This study aimed to characterize the clinicopathological features of ICJ-CAs.

METHOD

All ileal and colorectal resections for carcinoma, performed in Calgary, Canada between January 2009 and June 2012, were reviewed. Carcinomas in which the epicentre was within 5 cm of the ileocaecal valve (ICV) were defined as ICJ-CAs. Of 1003 carcinomas studied, 199 (19.8%) were ICJ-CAs, including 93 (9.3%) that crossed the ICV. Comparison of clinicopathological features with carcinomas of the other ileo-colorectal regions was made. Survival was also assessed.

RESULTS

Clinically, ICJ-CAs were more common in female than male patients (56.3% female) compared with left-colonic (42.9% female) and rectal (37.9% female) carcinomas, and were more common in older age-groups of patients (71.8 ± 12.7 years) compared with appendiceal (62.6 ± 11.3 years), left-colonic (69.4 ± 12.3 years) and rectal (67.1 ± 11.9 years) carcinomas. Macroscopically, ICJ-CAs were similar to other colorectal carcinomas and were mostly described as ulcerated (63.3%). Histologically, ICJ-CAs had more mucinous, signet-ring cell and/or neuroendocrine features (39.7%, 8.0% and 7.5%, respectively) than did carcinomas of the left colon (16.8%, 1.6% and 1.1%, respectively) and the rectum (14.1%, 1.0% and 0.0%, respectively). They were higher grade (20.1% were high grade) than those of the left-colon (10.3%) and the rectum (9.8%). ICJ-CAs presented at a higher T-stage (25.6% were T4) compared with rectal carcinomas (11.6%). Most significantly, ICJ-CAs presented at a higher N-stage (25.6% were N2) than did right-colonic (14.1%) and rectal (16.2%) carcinomas. Although survival of patients with ICJ-CAs did not differ from those with right-colonic carcinomas, those with carcinomas directly involving the ICV did show a significantly decreased survival.

CONCLUSION

ICJ-CAs display several distinct clinicopathological features that may require special diagnostic, prognostic and management attention.

Computed tomography colonography in 2014: an update on technique and indications

Twenty years after its introduction, computed tomographic colonography (CTC) has reached its maturity, and it can reasonably be considered the best radiological diagnostic test for imaging colorectal cancer (CRC) and polyps. This examination technique is less invasive than colonoscopy (CS), easy to perform, and standardized. Reduced bowel preparation and colonic distention using carbon dioxide favor patient compliance. Widespread implementation of a new image reconstruction algorithm has minimized radiation exposure, and the use of dedicated software with enhanced views has enabled easier image interpretation. Integration in the routine workflow of a computer-aided detection algorithm reduces perceptual errors, particularly for small polyps. Consolidated evidence from the literature shows that the diagnostic performances for the detection of CRC and large polyps in symptomatic and asymptomatic individuals are similar to CS and are largely superior to barium enema, the latter of which should be strongly discouraged. Favorable data regarding CTC performance open the possibility for many different indications, some of which are already supported by evidence-based data: incomplete, failed, or unfeasible CS; symptomatic, elderly, and frail patients; and investigation of diverticular disease. Other indications are still being debated and, thus, are recommended only if CS is unfeasible: the use of CTC in CRC screening and in surveillance after surgery for CRC or polypectomy. In order for CTC to be used appropriately, contraindications such as acute abdominal conditions (diverticulitis or the acute phase of inflammatory bowel diseases) and surveillance in patients with a long-standing history of ulcerative colitis or Crohn's disease and in those with hereditary colonic syndromes should not be overlooked. This will maximize the benefits of the technique and minimize potential sources of frustration or disappointment for both referring clinicians and patients.

Narrow band imaging vs. high definition colonoscopy for detection of colorectal adenomas in patients with positive faecal occult blood test: a randomised trial

BACKGROUND

The impact of narrow band imaging in improving the adenoma detection rate in a screening scenario is still unclear.

AIM

To evaluate whether narrow band imaging compared with high definition white light colonoscopy can enhance the adenoma detection rate during screening colonoscopy.

METHODS

Consecutive patients presenting for screening colonoscopy were included into this study and were randomly assigned to the narrow band imaging group (Group 1) or standard colonoscopy group (Group 2). Primary end point was the adenoma detection rate and secondary aim was the detection rate of advanced adenomas.

RESULTS

Overall, 117 patients were allocated to Group 1 and 120 to Group 2. Both the adenoma detection rate and the detection rate of advanced adenomas were not significantly different between the two groups (respectively, 52.1% vs. 55%, RR=0.95, 95% CI 0.75-1.20; 32.5% vs. 44.2%, RR=0.74, 95% CI 0.53-1.02). No significant difference between the proportions of polypoid and flat adenomas was found. Male gender, no prior history of screening, and endoscopist's adenoma detection rate were independent predictive factors of higher advanced adenoma detection rate.

CONCLUSIONS

In a screening scenario, narrow band imaging did not improve the adenoma nor advanced adenoma detection rates compared to high definition white light colonoscopy.

Endoscopic resection for superficial colorectal neoplasia in Italy: a prospective multicentre study

BACKGROUND

Since there are few prospective studies on colorectal endoscopic resection to date, we aimed to prospectively assess safety and efficacy of endoscopic resection in a cohort of Italian patients.

METHODS

Prospective multicentre assessment of resection of sessile polyps or non-polypoid lesions ≥10mm in size or smaller (if depressed). Outcome measures included complete excision, morbidity, mortality, and residual/recurrence at 12 months.

RESULTS

Overall, 1012 resections in 928 patients were analysed (62.4% sessile polyps, 28.8% laterally spreading tumours, 8.7% depressed non-polypoid lesions). Lesions were prevalent in the proximal colon. En bloc resection was possible in 715/1012 cases (70.7%), whereas piecemeal resection was required in 297 (29.3%). Endoscopically complete excision was achieved in 866 cases (85.6%). Adverse events occurred in 83 (8.2%), and no deaths occurred. Independent predictors of 12-month residual/recurrence were the location of the lesion in the proximal colon (OR 2.22 [95% CI 1.16-4.26]; p=0.015) and piecemeal endoscopic resection (OR 2.76 [95% CI 1.56-4.87]; p=0.0005). Limitations of the study were: potential expertise bias, no data on eligible and potentially resectable excluded lesions, high percentage of lesions<20mm, follow-up limited to 1 year.

CONCLUSION

In this registry study the endoscopic resection of colorectal lesions was safe and achieved high rates of long-term endoscopic clearance.

Anatomic distribution of cancers and colorectal adenomas according to age and sex and relationship between proximal and distal neoplasms in an i-FOBT-positive average-risk Italian screening cohort

BACKGROUND AND AIMS

Subsite-specific incidence rates of colorectal cancer (CRC) and adenomas may vary considerably by race, sex and age as well as due to different screening strategies. We assessed variations in the anatomical distribution of adenomas according to age and sex in an average-risk screening cohort testing positive at immunological faecal occult blood test (i-FOBT) in northern Italy.

METHODS

Data from 2,281 consecutive asymptomatic i-FOBT-positive subjects ageing 50-70 years undergone colonoscopy were reviewed. Size, number, macroscopic and histological features of all adenomas found as well as their proximal or distal location in relation to the splenic flexure were examined. Odds ratios (OR) of proximal neoplasms, according to the presence of distal neoplasms and other selected covariates were assessed by multiple logistic regression analysis.

RESULTS

A total of 2,599 neoplasms were found in 1,396 patients. Of these, 116 (5 %) were colorectal cancers, diagnosed in 106 patients. Out of 2,483 adenomas found, 1,564 (63 %) were sessile, 795 (32 %) were peduncolated and 124 (5 %) were flat-type; 54 % of all adenomas were tubular, 36 % were tubulovillous or villous, and 10 % were serrated adenomas. The majority of neoplasms (66 %) were located in the distal colon. Tumour subsite distribution was consistent in both sexes, whereas significant proximal migration of neoplasms occurred in the older age cohort. Indeed, the rate of proximal neoplasms in patients aged ≥60 years was 37 % as compared with 29 % in those ageing 50-59 years. Male gender (OR 1.84), age of 60 years or older (OR 1.44), having a family history of colorectal neoplasms (OR 1.47) and presence of at least 1 distal advanced adenoma (OR 1.63) were all significant predictors of advanced proximal neoplasms.

CONCLUSIONS

A left to right shift of colorectal adenomas with increasing age is evident in northern Italian asymptomatic i-FOBT-positive population. Advanced proximal neoplasms are not uncommon in subjects with or without distal adenomas, especially after 60 years of age. This should be carefully considered when implementing public screening strategies for CRC since the use of flexible sigmoidoscopy as a screening tool, particularly in older age groups, appears to be less effective.

Clinicopathological characteristics of laterally spreading colorectal tumor

BACKGROUND AND AIMS

Laterally spreading tumor (LST) is a colorectal pre-cancerous lesion. Previous studies have demonstrated distinct LST clinicopathological characteristics in different populations. This study evaluated clinicopathological characteristics of LST in a Chinese population.

METHODS

A total of 259 Chinese LST patients with 289 lesions were recruited for endoscopic and clinicopathological analyses.

RESULTS

Among these 289 lesions, 185 were granular type (LST-G), whereas 104 were non-granular type (LST-NG). LST-G lesions were further classified into homogeneous G-type and nodular mixed G-type, while LST-NG lesions were further classified into flat elevated NG-type and pseudo-depressed NG-type. Clinically, these four LST subtypes showed distinct clinicopathological characteristics, e.g., lesion size, location, or histopathological features (high-grade intraepithelial neoplasia and submucosal carcinoma). The nodular mixed G-type showed larger tumor size and higher incidence of high-grade intraepithelial neoplasia compared to the other three subtypes, while pseudo-depressed NG-type lesions showed the highest incidence of submucosal carcinoma. Noticeably, no diffidence was detected between the lesions of homogeneous G-type and flat elevated NG-type with regard to the histopathological features. Histology of the malignancy potential was associated with nodular mixed G-type [OR = 2.41, 95% CI (1.09-5.29); P = 0.029], flat elevated NG-type [OR = 3.49, 95% CI (1.41-8.22); P = 0.007], Diameter ≥30 mm [OR = 2.56, 95% CI (1.20-5.20); P = 0.009], Villous adenoma [OR = 2.76, 95% CI (1.01-7.58); P = 0.048] and serrated adenoma [OR = 6.99, 95% CI (1.81-26.98); P = 0.005].

CONCLUSION

Chinese LSTs can be divided into four different subtypes, which show distinct clinicopathological characteristics. Morphology, size and pathological characteristics are all independent predictors of advanced histology.

Promoter methylation of Wnt-antagonists in polypoid and nonpolypoid colorectal adenomas

BACKGROUND

Nonpolypoid adenomas are a subgroup of colorectal adenomas that have been associated with a more aggressive clinical behaviour compared to their polypoid counterparts. A substantial proportion of nonpolypoid and polypoid adenomas lack APC mutations, APC methylation or chromosomal loss of the APC locus on chromosome 5q, suggesting the involvement of other Wnt-pathway genes. The present study investigated promoter methylation of several Wnt-pathway antagonists in both nonpolypoid and polypoid adenomas.

METHODS

Quantitative methylation-specific PCR (qMSP) was used to evaluate methylation of four Wnt-antagonists, SFRP2, WIF-1, DKK3 and SOX17 in 18 normal colorectal mucosa samples, 9 colorectal cancer cell lines, 18 carcinomas, 44 nonpolypoid and 44 polypoid adenomas. Results were integrated with previously obtained data on APC mutation, methylation and chromosome 5q status from the same samples.

RESULTS

Increased methylation of all genes was found in the majority of cell lines, adenomas and carcinomas compared to normal controls. WIF-1 and DKK3 showed a significantly lower level of methylation in nonpolypoid compared to polypoid adenomas (p < 0.01). Combining both adenoma types, a positive trend between APC mutation and both WIF-1 and DKK3 methylation was observed (p < 0.05).

CONCLUSIONS

Methylation of Wnt-pathway antagonists represents an additional mechanism of constitutive Wnt-pathway activation in colorectal adenomas. Current results further substantiate the existence of partially alternative Wnt-pathway disruption mechanisms in nonpolypoid compared to polypoid adenomas, in line with previous observations.

Chromocolonoscopy

Chromocolonoscopy is the process of endoscopically examining the colon mucosa after it has been stained with dye. The goal is to allow the endoscopist to identify subtle features in the mucosa, such as morphologically flat polyps or crypt patterns. Studies examining the efficacy of chromocolonoscopy to identify adenomas missed by conventional colonoscopy have shown that although chromocolonoscopy increases polyp yield, most additional lesions are small in size. Staining can also help in differentiating neoplastic from non-neoplastic polyps. Perhaps the most useful aspect of chromocolonoscopy is increasing the yield for dysplasia in patients undergoing colonoscopy for inflammatory bowel disease surveillance.

Tracking the molecular features of nonpolypoid colorectal neoplasms: a systematic review and meta-analysis

OBJECTIVES

Nonpolypoid colorectal neoplasms (NP-CRNs) are proposed as a major contributor to the occurrence of interval cancers, but their underlying biology remains controversial. We conducted a systematic review and meta-analysis to clarify the major biological events in NP-CRNs.

METHODS

We systematically searched for studies examining molecular characteristics of NP-CRNs. We performed random effect meta-analyses. We measured the heterogeneity among studies using I(2) and possible publication bias using funnel plots.

RESULTS

Fifty-three studies on KRAS, APC, or BRAF mutations, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), or DNA promoter hypermethylation were included. We observed less KRAS mutations (summary odds ratio (OR) 0.30, confidence interval (CI)=0.19-0.46, I(2)=77.4%, CI=70.1-82.9) and APC mutations (summary OR 0.42, CI=0.24-0.72, I(2)=22.6%, CI=0.0-66.7) in NP-CRNs vs. protruded CRNs, whereas BRAF mutations were more frequent (summary OR 2.20, CI=1.01-4.81, I(2)=0%, CI=0-70.8), albeit all with large heterogeneity. Less KRAS mutations were especially found in NP-CRNs subtypes: depressed CRNs (summary OR 0.12, CI=0.05-0.29, I(2)=0%, CI=0-67.6), non-granular lateral spreading tumors (LSTs-NG) (summary OR 0.61, CI=0.37-1.0, I(2)=0%, CI=0-74.6), and early nonpolypoid carcinomas (summary OR 0.11, CI=0.06-0.19, I(2)=0%, CI=0-58.3). MSI frequency was similar in NP-CRNs and protruded CRNs (summary OR 0.99, CI=0.21-4.71, I(2)=70.3%, CI=38.4-85.7). Data for promoter hypermethylation and CIMP were inconsistent, precluding meaningful conclusions.

CONCLUSIONS

This meta-analysis provides indications that NP-CRNs are molecularly different from protruded CRNs. In particular, some subtypes of NP-CRNs, the depressed and LST-NG, are featured by less KRAS mutations than polypoid CRNs. Prospective, multicenter studies are needed to clarify the molecular pathways underlying nonpolypoid colorectal carcinogenesis and potential implications for surveillance intervals.

Polyp and adenoma detection rates in the proximal and distal colon

OBJECTIVES

Little is known about the correlation between the polyp detection rate (PDR) and the adenoma detection rate (ADR) in individual colonic segments. The adenoma-to-polyp detection rate quotient (APDRQ) has been utilized in retrospective study as a constant to estimate ADR from PDR. It has been previously stated that diminutive polyps in the rectum are more likely to be non-adenomatous, compared with more proximal segments, yet the APDRQ uses data from the entire colon. We sought to characterize and compare ADR and PDR in each colonic segment, estimate ADR using the conversion factor, APDRQ, and assess the correlation between estimated and actual ADR for each colonic segment.

METHODS

As part of a quality improvement program, a retrospective chart review was conducted of all outpatient colonoscopies performed by 20 gastroenterologists between 1 October 2010 and 31 March 2011 at a single academic tertiary-care referral center. PDR, ADR, and the APDRQ were calculated for each gastroenterologist, using data from the entire colon and then for each colonic segment separately. Actual ADR was compared with estimated ADR based on the measured APDRQ.

RESULTS

During 1,921 colonoscopies, 2,285 polyps were removed; 1,122 (49%) were adenomas. The mean (s.d.) PDR for the group was 49% (12.4%) (range, 16-64%). The mean (s.d.) ADR was 31% (7.4%) (range, 13-42%). PDR and ADR correlated well in segments proximal to the splenic flexure, but diverged in distal segments. ADR was significantly higher in the right colon (17.1%) than in the left (13.5%) (P=0.001). The correlation between estimated and actual ADR using the APDRQ was significantly higher in the right colon (r=0.95 (95% confidence interval (CI), 0.87-0.98)) than in the left (r=0.59 (95% CI, 0.17-0.83)) (P<0.05).

CONCLUSIONS

Although PDR and ADR correlate well in segments proximal to the splenic flexure, they do not correlate well in the left colon. Caution should be exercised when using PDR as a surrogate for ADR if data from the rectum and sigmoid are included.

Precancerous lesions in colorectal cancer

Colorectal cancer (CRC) is the third most common cause of cancer death in the world. The incidence rate (ASR) and age distribution of this disease differ between most of African-Middle-Eastern (AMAGE) and North America and Europe for many reasons. However, in all areas, "CRC" is considered as one of the most preventable cancers, because it might develop from variant processes like polyps and IBD in addition to the genetic pathogenesis which became very well known in this disease. We tried in this paper to review all the possible reasons of the differences in incidence and age between the west and AMAGE. Also we reviewed all the mutations that lead to the hereditary and familiar clustering of this disease with the correlations with the surrounding food and environment of different areas. Then, we focused on the precancerous pathology of this disease with special focusing on early detection depending on new endoscopy technology and most important genetic studies. We lastly reviewed the evidence of some of the surveillance and put suggestions about future surveillance programs and how important those programs are on the psychological aspect of the patients and their families.

Comprehensive mutation analysis in colorectal flat adenomas

BACKGROUND

Flat adenomas are a subgroup of colorectal adenomas that have been associated with a distinct biology and a more aggressive clinical behavior compared to their polypoid counterparts. In the present study, we aimed to compare the mutation spectrum of 14 cancer genes, between these two phenotypes.

METHODS

A consecutive series of 106 flat and 93 polypoid adenomas was analyzed retrospectively for frequently occurring mutations in "hot spot" regions of KRAS, BRAF, PIK3CA and NRAS, as well as selected mutations in CTNNB1 (β-catenin), EGFR, FBXW7 (CDC4), PTEN, STK11, MAP2K4, SMAD4, PIK3R1 and PDGFRA using a high-throughput genotyping technique. Additionally, APC was analyzed using direct sequencing.

RESULTS

APC mutations were more frequent in polypoid adenomas compared to flat adenomas (48.5% versus 30.3%, respectively, p = 0.02). Mutations in KRAS, BRAF, NRAS, FBXW7 and CTNNB1 showed similar frequencies in both phenotypes. Between the different subtypes of flat adenomas (0-IIa, LST-F and LST-G) no differences were observed for any of the investigated genes.

CONCLUSION

The lower APC mutation rate in flat adenomas compared to polypoid adenomas suggests that disruption of the Wnt-pathway may occur via different mechanisms in these two phenotypes. Furthermore, in contrast to previous observations our results in this large well-defined sample set indicate that there is no significant association between the different morphological phenotypes and mutations in key genes of the RAS-RAF-MAPK pathway.

[Korean guidelines for colorectal cancer screening and polyp detection]

Colorectal cancer is the second most common cancer in males and the fourth most common in females in Korea. Since the most of colorectal cancer occur through the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. Korean Multi-Society Take Force developed the guidelines with evidence-based methods. Parts of the statements drawn by systematic reviews and meta-analyses. Herein we discussed the epidemiology of colorectal cancers and adenomas in Korea, optimal screening methods for colorectal cancer, and detection for adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.

Current status on performance of CT colonography and clinical indications

CT colonography (CTC) is a robust and reliable imaging test of the colon. Accuracy for the detection of colorectal cancer (CRC) is as high as conventional colonoscopy (CC). Identification of polyp is size dependent, with large lesions (≥10mm) accurately detected and small lesions (6-9mm) identified with moderate to good sensitivity. Recent studies show good sensitivity for the identification of nonpolypoid (flat) lesions as well. Current CTC indications include the evaluation of patients who had undergone a previous incomplete CC or those who are unfit for CC (elderly and frail individuals, patients with underlying severe clinical conditions, or with contraindication to sedation). CTC can also be efficiently used in the assessment of diverticular disease (excluding patients with acute diverticulitis, where the exam should be postponed), before laparoscopic surgery for CRC (to have an accurate localization of the lesion), in the evaluation of colonic involvement in the case of deep pelvic endometriosis (replacing barium enema). CTC is also a safe procedure in patients with colostomy. For CRC screening, CTC should be considered an opportunistic screening test (not available for population, or mass screening) to be offered to asymptomatic average-risk individuals, of both genders, starting at age 50. The use in individuals with positive family history should be discussed with the patient first. Absolute contraindication is to propose CTC for surveillance of genetic syndromes and chronic inflammatory bowel diseases (in particular, ulcerative colitis). The use of CTC in the follow-up after surgery for CRC is achieving interesting evidences despite the fact that literature data are still relatively weak in terms of numerosity of the studied populations. In patients who underwent previous polypectomy CTC cannot be recommended as first test because debate is still open. It is desirable that in the future CTC would be the first-line and only diagnostic test for colonic diseases, leaving to CC only a therapeutic role.

Association between colonoscopy and colorectal cancer mortality in a US cohort according to site of cancer and colonoscopist specialty

PURPOSE

We designed this study to evaluate the association of colonoscopy with colorectal cancer (CRC) death in the United States by site of CRC and endoscopist specialty.

METHODS

We designed a case-control study using Surveillance, Epidemiology, and End Results (SEER)-Medicare data. We identified patients (cases) diagnosed with CRC age 70 to 89 years from January 1998 through December 2002 who died as a result of CRC by 2007. We selected three matched controls without cancer for each case. Controls were assigned a referent date (date of diagnosis of the case). Colonoscopy performed from January 1991 through 6 months before the diagnosis/referent date was our primary exposure. We compared exposure to colonoscopy in cases and controls by using conditional logistic regression controlling for covariates, stratified by site of CRC. We determined endoscopist specialty by linkage to the American Medical Association (AMA) Masterfile. We assessed whether the association between colonoscopy and CRC death varied with endoscopist specialty.

RESULTS

We identified 9,458 cases (3,963 proximal [41.9%], 4,685 distal [49.5%], and 810 unknown site [8.6%]) and 27,641 controls. In all, 11.3% of cases and 23.7% of controls underwent colonoscopy more than 6 months before diagnosis. Compared with controls, cases were less likely to have undergone colonoscopy (odds ratio [OR], 0.40; 95% CI, 0.37 to 0.43); the association was stronger for distal (OR, 0.24; 95% CI, 0.21 to 0.27) than proximal (OR, 0.58; 95% CI, 0.53 to 0.64) CRC. The strength of the association varied with endoscopist specialty.

CONCLUSION

Colonoscopy is associated with a reduced risk of death from CRC, with the association considerably and consistently stronger for distal versus proximal CRC. The overall association was strongest if colonoscopy was performed by a gastroenterologist.

Colorectal endoscopic submucosal dissection in Japan and Western countries

Various studies by Japanese endoscopists have demonstrated that colorectal endoscopic submucosal dissection (ESD) can overcome technical limitations of the endoscopic mucosal resection (EMR) technique such as piecemeal resection for flat lesions larger than 20 mm, resection of lesions involving the dentate line or the ileocecal valve and lesions with the non-lifting sign, and achieve higher en bloc resection rate. However, it is infrequently performed in Western countries in comparison with Japan, despite the advantages explained above. There are some differences between Japan and Western countries in environments and clinical settings for performing ESD in the colorectum. Endoscopists who perform colorectal ESD around the world are considering that refinements in ESD techniques, devices and training will be necessary to further reduce a higher risk of complications and longer procedure times before adoption of ESD can be recommended on a widespread international scale.

Korean guidelines for colorectal cancer screening and polyp detection

Now colorectal cancer is the second most common cancer in males and the fourth most common cancer in females in Korea. Since most of colorectal cancers occur after the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. The guideline was developed by the Korean Multi-Society Take Force and we tried to establish the guideline by evidence-based methods. Parts of the statements were draw by systematic reviews and meta-analyses. Herein we discussed epidemiology of colorectal cancers and adenomas in Korea and optimal methods for screening of colorectal cancer and detection of adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.

Nonpolypoid colorectal neoplasms: gender differences in prevalence and malignant potential

OBJECTIVE

Colonoscopy may fail to prevent colorectal cancer, especially in the proximal colon and in women. Nonpolypoid colorectal neoplasms may potentially explain some of these post-colonoscopy cancers. In the present study, we aimed to examine the prevalence and malignant potential of nonpolypoid colorectal neoplasms in a large population, with special attention to gender and location.

METHODS

We performed a cross-sectional study of all consecutive patients undergoing elective colonoscopy at a single academic medical center. The endoscopists were familiarized on the detection and treatment of nonpolypoid lesions. Advanced histology was defined by the presence of high-grade dysplasia or early cancer.

RESULTS

We included 2310 patients (53.9% women, mean age 58.4 years) with 2143 colorectal polyps. Prevalences of colorectal neoplasms and nonpolypoid colorectal neoplasms were lower in women than in men (20.9% vs. 33.7%, p < 0.001 and 3.0% vs. 5.5%, p = 0.002). In women, nonpolypoid colorectal neoplasms were significantly more likely to contain advanced histology than polypoid ones (OR 2.89, 95% CI 1.24-6.74, p = 0.01), while this was not the case in men (OR 0.91, 95% CI 0.40-2.06, p = 0.83). Proximal neoplasms with advanced histology were more likely to be nonpolypoid than distal ones (OR 4.68, 95% CI 1.54-14.2, p = 0.006).

CONCLUSION

Nonpolypoid mechanisms may play an important role in colorectal carcinogenesis, in both women and men. Although women have fewer colorectal neoplasms than men, they have nonpolypoid colorectal neoplasms, which frequently contain advanced histology.

Improving protection against proximal colon cancer by colonoscopy

Colonoscopy protection against proximal cancer can be achieved, but the level of protection has thus far been less than left colon protection. Improved proximal protection begins with effective right colon bowel preparation, best achieved by split dosing the preparation regimen. Cecal intubation in screening examinations should exceed 95%, and must be documented by photography. Examiners must be proficient in detection of subtle right colon lesions, including serrated lesions as well as flat and depressed adenomas. Effective examination should be demonstrated by meeting recommended targets for adenoma detection.

Colorectal cancer screening: update for 2011

Colorectal cancer is the third most common cancer in the United States. Although mortality and incidence rates are declining in the United States, colorectal cancer screening remains underused. In addition, recent data suggest that colonoscopy, which is often considered the gold standard for colorectal cancer screening, is less protective for right-sided tumors, which are more likely to be flat or depressed and are more affected by an inadequate bowel preparation. Imaging technologies such as chromoendoscopy and narrow band imaging have been developed to improve delineation of suspicious lesions during colonoscopy. In addition, other new modalities such as computed tomography colonography (CTC), capsule endoscopy, fecal immunochemical tests, and fecal DNA tests may offer less invasive screening options for patients who decline colonoscopy.