A quantitative assessment of the risks and cost savings of forgoing histologic examination of diminutive polyps

High-definition vs. standard-definition endoscopy with indigo carmine for the in vivo diagnosis of colonic polyps

BACKGROUND

There is growing evidence that indigo carmine chromoendoscopy is effective for the in vivo diagnosis of colonic polyps. However, the impact of colonoscope resolution on diagnostic accuracy has not been investigated.

OBJECTIVE

We aimed to compare the effectiveness of in vivo diagnosis of small colonic polyps using indigo carmine dye spray with standard-definition and high-definition colonoscopes.

METHODS

Procedures were performed using Fujinon colonoscopes and EPX 4400 processor. Fujinon standard-definition (SD) and high-definition (HD) colonoscopes were used, with the endoscopist blinded to colonoscope definition. Polyps <10 mm were assessed using 0.2% indigo carmine dye spray, with the predicted diagnosis recorded. In each case the kind of colonoscope (SD or HD) was recorded. Polyps were removed and sent for histological analysis, with the pathologist blinded to the diagnosis made by the endoscopist. The predicted diagnosis was compared with the true histology to calculate the accuracy, sensitivity and specificity of in vivo assessment using either SD or HD scopes.

RESULTS

In total 237 polyps <10 mm in size were examined. There was no statistically significant difference for any of the measured parameters between SD and HD assessments, with an accuracy, sensitivity and specificity of 89%, 91% and 87% with SD colonoscopes and 92%, 96% and 84% with HD colonoscopes.

CONCLUSIONS

The accuracy of in vivo assessment of small colonic polyps with indigo carmine dye spray is excellent with standard-definition colonoscopes and is not improved with high-definition colonoscopes.

Current status and future perspectives of endoscopic diagnosis and treatment of diminutive colorectal polyps

During colonoscopy, small and diminutive colorectal polyps are commonly encountered. It is estimated that at least one adenomatous polyp is detected in almost half of all patients undergoing screening colonoscopy. In contrast, the 'predict, resect, and discard' strategy for diminutive and small colorectal polyps is a current topic especially in Western countries. 'Is this an acceptable policy in Japan?' Herein, we report the results of a questionnaire survey with regard to the management of diminutive colorectal polyps, including the thoughts of Japanese endoscopists regarding the 'predict, resect, and discard' strategy. At the moment, we propose that this strategy should be used by skilled endoscopists only.

Proposal of a new 'resect and discard' strategy using magnifying narrow band imaging: pilot study of diagnostic accuracy

BACKGROUND AND AIM

A 'resect and discard' strategy using non-magnifying narrow band imaging (N-NBI) has been proposed for reducing screening colonoscopy costs, but it does not take into consideration advanced histology and magnifying NBI (M-NBI) that can potentially further improve the 'resect and discard' strategy. We conducted a pilot study to investigate the feasibility of M-NBI for the new 'resect and discard' strategy with consideration for advanced histology.

METHODS

The present study involved 63 patients. For each polyp, optical diagnosis was independently made using N-NBI and M-NBI, a decision (discard or send for pathology) was made based on the M-NBI findings, and histological and optical diagnosis results were compared.

RESULTS

Sensitivity, specificity and accuracy (95% confidence interval) of M-NBI for lesions with advanced histology were 1.00 (0.36-1.00), 0.92 (0.91-0.92) and 0.92 (0.90-0.92), respectively. Whereas the management of 86% of small polyps could be decided without formal histopathology, lesions with advanced histology were not discarded using M-NBI. The diagnostic accuracy of M-NBI in distinguishing neoplastic from non-neoplastic lesions was higher than that of N-NBI.

CONCLUSIONS

We propose a new resect and discard strategy with advanced histology using M-NBI that is a promising strategy to reduce the costs of histopathology and to minimize the risk of discarding important lesions.

A review of image-enhanced endoscopy in the evaluation of colonic polyps

The practice of colonoscopy has changed considerably over the last decade. The growth of image-enhanced endoscopy have altered our concepts of how we perform colonoscopy. This article examines the evidence base behind these techniques and looks at where future research needs to be directed.

Impact of a computer-based teaching module on characterization of diminutive colon polyps by using narrow-band imaging by non-experts in academic and community practice: a video-based study

BACKGROUND

Experts can accurately characterize the histology of diminutive polyps with narrow-band imaging (NBI). There are limited data on the performance of non-experts.

OBJECTIVE

To assess the impact of a computer-based teaching module on the accuracy of predicting polyp histology with NBI by non-experts (in academics and community practice) by using video clips.

DESIGN

Prospective, observational study.

SETTING

Academic and community practice.

PARTICIPANTS

A total of 15 gastroenterologists participated-5 experts in NBI, 5 non-experts in academic practice, and 5 non-experts in community practice.

INTERVENTION

Participants reviewed a 20-minute, computer-based teaching module outlining the different NBI features for hyperplastic and adenomatous polyps.

MAIN OUTCOME MEASUREMENTS

Performance characteristics in characterizing the histology of diminutive polyps with NBI by using short video clips before (pretest) and after (posttest) reviewing the teaching module.

RESULTS

Non-experts in academic practice showed a significant improvement in the sensitivity (54% vs 79%; P < .001), accuracy (64% vs 81%; P < .001), and proportion of high-confidence diagnoses (49% vs 69%; P < .001) in the posttest. Non-experts in community practice had significantly higher sensitivity (58% vs 75%; P = .004), specificity (76% vs 90%; P = .04), accuracy (64% vs 81%; P < .001), and proportion of high-confidence diagnoses (49% vs 72%; P < .001) in the posttest. Performance of experts in NBI was significantly better than non-experts in both academic and community practice.

LIMITATIONS

Selection bias in selecting good quality videos. Performance not assessed during live colonoscopy.

CONCLUSION

Academic and community gastroenterologists without prior experience in NBI can achieve significant improvements in characterizing diminutive polyp histology after a brief computer-based training. The durability of these results and applicability in everyday practice are uncertain.

Narrow band imaging to differentiate neoplastic and non-neoplastic colorectal polyps in real time: a meta-analysis of diagnostic operating characteristics

PURPOSE

Many studies have reported on the use of narrow band imaging (NBI) colonoscopy to differentiate neoplastic from non-neoplastic colorectal polyps. It has potential to replace pathological diagnosis of diminutive polyps. We aimed to perform a systematic review and meta-analysis on the real-time diagnostic operating characteristics of NBI colonoscopy.

METHODS

We searched PubMed, SCOPUS and Cochrane databases and abstracts. We used a two-level bivariate meta-analysis following a random effects model to summarise the data and fit hierarchical summary receiver-operating characteristic (HSROC) curves. The area under the HSROC curve serves as an indicator of the diagnostic test strength. We calculated summary sensitivity, specificity and negative predictive value (NPV). We assessed agreement of surveillance interval recommendations based on endoscopic diagnosis compared to pathology.

RESULTS

For NBI diagnosis of colorectal polyps, the area under the HSROC curve was 0.92 (95% CI 0.90 to 0.94), based on 28 studies involving 6280 polyps in 4053 patients. The overall sensitivity was 91.0% (95% CI 87.6% to 93.5%) and specificity was 82.6% (95% CI 79.0% to 85.7%). In eight studies (n=2146 polyps) that used high-confidence diagnostic predictions, sensitivity was 93.8% and specificity was 83.3%. The NPVs exceeded 90% when 60% or less of all polyps were neoplastic. Surveillance intervals based on endoscopic diagnosis agreed with those based on pathology in 92.6% of patients (95% CI 87.9% to 96.3%).

CONCLUSIONS

NBI diagnosis of colorectal polyps is highly accurate--the area under the HSROC curve exceeds 0.90. High-confidence predictions provide >90% sensitivity and NPV. It shows high potential for real-time endoscopic diagnosis.

Cold snare polypectomy vs. Cold forceps polypectomy using double-biopsy technique for removal of diminutive colorectal polyps: a prospective randomized study

OBJECTIVES

There are few data on cold snare polypectomy (CSP) in direct comparison with cold forceps polypectomy (CFP) for colonoscopic resection of diminutive colorectal polyps (DCPs; ≤5 mm). The primary aim of this study was to compare the histologic polyp eradication rate of CSP with that of CFP using double-biopsy technique.

METHODS

This was a randomized controlled trial at a single academic hospital. Of the 165 patients invited, 54 consecutive patients having 117 eligible polyps were enrolled in this study. To evaluate histologic eradication of polyps, two or more additional biopsies were taken from the base and edges of the polypectomy site.

RESULTS

The mean size of polyps was 3.66 mm (±1.13). Most polyps evaluated were tubular adenomas (69.9%). The rate of histologic eradication was significantly higher in the CSP group than in the CFP group (93.2% vs. 75.9%, P=0.009). The time taken for polypectomy was significantly shorter in the CSP group (14.29 vs. 22.03 s, P<0.001). Failure of tissue retrieval was noted in 6.8% of polyps resected by CSP. Multivariate analysis revealed that the method of polypectomy (CFP) and the polyp size (≥4 mm) were independent predictors associated with incomplete histologic eradication (odds ratio (OR) 4.750 (95% confidence interval (CI): 1.459-15.466), OR 4.375 (95% CI: 1.345-14.235); all P<0.05, respectively).

CONCLUSIONS

CSP is superior to CFP for the endoscopic removal of DCPs with regard to completeness of polypectomy. CSP technique should be considered the primary method for endoscopic treatment of polyps in the 4-5-mm size range (ClinicalTrials.gov number: NCT01646242).

Incidence of diagnostic change in colorectal polyp specimens after deeper sectioning at 2 different laboratories staffed by the same pathologists

OBJECTIVES

To calculate the incidence of nondiagnostic (ND) colorectal (CR) polyp cases in which deeper tissue sectioning rendered new diagnostic information--particularly adenomas--in 2 laboratories staffed by the same pathologists.

METHODS

After initial diagnosis, 100 ND CR polyps from each laboratory were reexamined with 3 deeper levels to establish rates of diagnostic conversion based on biopsy specimen location and original observation(s).

RESULTS

Deeper sectioning rendered new diagnostic information in 43 (21.5%) of 200 biopsy specimens and specifically adenomas in 16 (8.0%) of 200 biopsy specimens.

CONCLUSIONS

These results support routine ordering of deeper levels on ND CR polyps to improve adenoma detection rates, especially those cases without any histologic abnormality. If another biopsy in the same case already is adenomatous, examination of deeper levels may not be necessary, as it may not have any significant effect on the clinical management of the patient.

Gastroenterology trainees can easily learn histologic characterization of diminutive colorectal polyps with narrow band imaging

BACKGROUND & AIMS

Little is known about how teaching gastroenterology trainees polyp patterns by using narrow band imaging (NBI) affects their ability to characterize the histology of diminutive colorectal polyps. We developed and tested a tool to teach trainees to characterize the histology of diminutive polyps by using NBI.

METHODS

Twelve gastroenterology trainees with varying levels of colonoscopy experience watched a teaching tool that described the NBI criteria to distinguish polyp histology. The trainees then watched 80 videos of NBI examination of diminutive polyps, recording their predictions of polyp histology and their degree of confidence. After each video, an expert provided feedback about actual polyp histology and the NBI criteria that supported each diagnosis. Twelve weeks later, without training or feedback during the interval, the trainees watched the same videos and predicted histologies of the polyps. Performance was evaluated by comparing predicted classification with actual histologic findings. Cumulative sum analysis was used to determine the learning curve for each trainee.

RESULTS

Trainees made significant improvements in accuracy and the proportion of high-confidence predictions as they progressed through video blocks during the first session (P < .001). With active feedback, all trainees predicted polyp histologies with >90% accuracy, with a negative predictive value >90% for adenomatous histology. A median of 49 videos was required to achieve competency. For diagnoses made with high confidence, trainee performance exceeded 90% during the first and second sessions. Interobserver agreement was substantial (session 1, κ = 0.71; session 2, κ = 0.70).

CONCLUSIONS

We developed a computer-based tool, combined with short videos and active feedback, to train gastroenterologists to identify polyp histology by using NBI. After training, gastroenterology trainees characterized the histology of diminutive polyps with ≥ 90% accuracy.

Classification criteria for advanced adenomas of the colon by using probe-based confocal laser endomicroscopy: a preliminary study

BACKGROUND

Probe-based confocal laser endomicroscopy may allow a strategy of "diagnose, resect, and discard" for small nonadvanced adenomas, but there are concerns about discarding polyps with advanced histology.

OBJECTIVE

The aim of this study was to evaluate the potential use of probe-based confocal laser endomicroscopy to aid in distinguishing low-grade from advanced colon adenomas.

DESIGN

Six observers, blinded to histopathology, scored 5 adenoma features and an overall diagnosis and confidence level for the diagnosis.

SETTING

This study was conducted at single, tertiary care referral center.

PATIENTS

Patients undergoing screening and surveillance colonoscopies and for whom an adenomatous polyp was removed were included.

INTERVENTIONS

A sample of 27 advanced adenomas and 120 nonadvanced adenomas were used in the study. An initial classification system was created with 10 advanced and 10 nonadvanced adenomas. The remaining 127 adenomas were scored by each observer in the validation portion of the study.

MAIN OUTCOME MEASURES

The primary outcome measured was the accurate classification of advanced and nonadvanced adenomas.

RESULTS

Overall, across all 6 observers, the sensitivity in correctly classifying advanced adenomas was 43%, the negative predictive value was 89%, the specificity was 71%, and the positive predictive value was 19%. No single feature or combination of features as seen with probe-based confocal laser endomicroscopy consistently identified advanced adenomas.

LIMITATIONS

Classification criteria were developed subjectively, and there was limited observer experience with probe-based confocal laser endomicroscopy use.

CONCLUSIONS

Our initial attempt at creating classification criteria for probe-based confocal laser endomicroscopy did not consistently distinguish advanced from nonadvanced adenomas and, therefore, is not useful in applying a "diagnose, resect, and discard" strategy. However, further refinement of our probe-based confocal laser endomicroscopy classification scheme in future studies has potential to accurately detect advanced histology in colorectal polyps.

Colonic polyps: are we ready to resect and discard?

Colorectal cancer represents a major cause of mortality in Western countries, and population-based colonoscopy screening is supported by official guidelines. A significant determinant of the cost of colonoscopy screening/surveillance is driven by polypectomy of diminutive (≤5 mm) lesions. When considering the low prevalence of advanced neoplasia within diminutive polyps, the additional cost of pathologic examination is mainly justified by the need to differentiate between precancerous adenomatous versus hyperplastic polyps. The aim of this review is to summarize the data supporting the clinical application of a resect and discard strategy, also addressing the potential pitfalls associated with this approach.

Clinicopathological features of colorectal polyps: evaluation of the 'predict, resect and discard' strategies

AIM

'Predict, resect and discard' strategies for diminutive and small colonic polyps are considered to be cost effective for treating colorectal cancers. The aim of this study was to determine, retrospectively, the histological features of colonic polyps resected by endoscopic procedures or surgery using an updated database.

METHOD

We retrospectively analysed the clinicopathological features of colorectal polyps, less than 20 mm in size, which were removed by endoscopy from January 2009 to November 2011 at the National Cancer Center Hospital (NCCH) in Tokyo, Japan.

RESULTS

Less than 1% of diminutive polyps (≤ 5 mm) were classified as mucosal high-grade neoplasia (Category 4), and no submucosal invasion by carcinoma (Category 5) lesions were noted. However, 3% of small polyps (6-9 mm) were classified as Category 5; of these, 6% were submucosal deep invasive cancers. Morphologically, depressed components were observed more frequently in carcinomas than in adenomas in both small and large polyps (10-20 mm).

CONCLUSION

In light of the 'predict, resect and discard' strategies for small polyps, we should pay attention to the possible clinical malignancy of small and large polyps. We recommend that these strategies should be applied selectively and that they should be informed by accurate endoscopic evaluations.

New paradigms for colonoscopic management of diminutive colorectal polyps: predict, resect, and discard or do not resect?

The possibility to predict in vivo the histology of colorectal polyps by advanced endoscopic imaging has resulted in the implementation of a more conservative management for diminutive lesions detected at colonoscopy. In detail, a predict-and-do-not-resect strategy has been proposed for diminutive lesions located in the rectosigmoid tract, whilst a predict-resect-and-discard policy has been advocated for nonrectosigmoid diminutive polyps. Recently, the American Society for Gastrointestinal Endoscopy set required thresholds to be met, before allowing the adoption of these policies in the clinical field. The ability of current endoscopic imaging in reaching these thresholds would depend on a complex interaction among the accuracy of advanced endoscopic imaging in differentiating between adenomatous and hyperplastic lesions, the prevalence of (advanced) neoplasia within diminutive lesions, and the type of surveillance intervals recommended. Aim of this review is to summarize the data supporting the application of both a predict-and-do-not-resect and a predict-resect-and-discard policies, also addressing the potential pitfalls associated with these strategies.

Optical diagnosis of small colorectal polyp histology with high-definition colonoscopy using narrow band imaging

Optical diagnosis of polyp histology can potentially result in enormous cost savings by way of the "resect and discard" strategy for diminutive polyps and the "do not resect" strategy for diminutive hyperplastic polyps in the distal colon. Narrow Band Imaging (NBI) highlights the surface mucosal and vascular pattern on polyps and has been shown to accurately characterize adenomatous and hyperplastic polyps by experts. However, the results have been a little discouraging amongst lesser experienced endoscopists. Studies have also shown that using the NBI diagnosis of diminutive polyp histology, experts can accurately define the future surveillance colonoscopy intervals. However nonexperts in academic or community setting have as yet failed to achieve the recommended thresholds. The subjectivity in assessment by endoscopists leads to the variable accuracy rates and can be circumvented by computer based automated tools. Although initial experience with a few computer based algorithms have shown accuracies comparable to experts, further refinement and validation will be required before these can be implemented in clinical practice. Incorporation of optical diagnosis of diminutive polyps into clinical practice is bound to face several hurdles. But the potential for enormous cost saving makes it an attractive strategy that can make colonoscopy more cost effective.

Validation of a simple classification system for endoscopic diagnosis of small colorectal polyps using narrow-band imaging

BACKGROUND & AIMS

Almost all colorectal polyps ≤ 5 mm are benign, yet current practice requires costly pathologic analysis. We aimed to develop and evaluate the validity of a simple narrow-band imaging (NBI)-based classification system for differentiating hyperplastic from adenomatous polyps.

METHODS

The study was conducted in 4 phases: (1) evaluation of accuracy and reliability of histologic prediction by NBI-experienced colonoscopists; (2) development of a classification based on color, vessels, and surface pattern criteria, using a modified Delphi method; (3) validation of the component criteria by people not experienced in endoscopy or NBI analysis (25 medical students, 19 gastroenterology fellows) using 118 high-definition colorectal polyp images of known histology; and (4) validation of the classification system by NBI-trained gastroenterology fellows, using still images. We performed a pilot evaluation during real-time colonoscopy.

RESULTS

We developed a classification system for the endoscopic diagnosis of colorectal polyp histology and established its predictive validity. When all 3 criteria were used, the specificity ranged from 94.9% to 100% and the combined sensitivity ranged from 8.5% to 61.0%. The specificities of the individual criteria were lower although the sensitivities were higher. During real-time colonoscopy, endoscopists made diagnoses with high confidence for 75% of consecutive small colorectal polyps, with 89% accuracy, 98% sensitivity, and 95% negative predictive values.

CONCLUSIONS

We developed and established the validity of an NBI classification system that can be used to diagnose colorectal polyps. In preliminary real-time evaluation, the system allowed endoscopic diagnoses of colorectal polyp histology.

A sessile (diminutive) polyp within a sigmoid diverticulum--EMR or observe?

Endoscopic mucosal resection (EMR) is a well-established technique for excision of colo-rectal polyps, which can be technically challenging when the polyp is inside a diverticulum, as colonic perforation may easily occur due to the lack of muscular coats. Here we report, to our knowledge, the first case of sessile (diminutive) polyp inside a diverticulum being successfully removed entirely by EMR.

Prevalence of advanced histological features in diminutive and small colon polyps

BACKGROUND

Investigators have proposed "predict, resect, and discard" strategies for diminutive (≤ 5 mm) or small (6-9 mm) polyps to reduce screening colonoscopy costs. Advanced histological features such as villous histology, high-grade dysplasia, and/or cancer in these polyps could deter adoption of these strategies.

OBJECTIVE

Determine the prevalence of advanced histological features in diminutive and small colon polyps.

DESIGN

Retrospective analysis of data from 3 prospective clinical trials.

SETTING

Two tertiary-care referral centers.

PATIENTS

This study involved patients undergoing screening or surveillance colonoscopy.

INTERVENTION

The location, size, and morphology of each polyp detected was documented. Each polyp was then resected, placed in a unique specimen jar, and sent for histopathological evaluation.

MAIN OUTCOME MEASUREMENTS

Rates of advanced histological features (villous histology, high-grade dysplasia, and cancer).

RESULTS

A total of 2361 polyps were detected, removed, and retrieved. Both diminutive and small polyps had a lower frequency of any advanced histological features compared with large polyps (0.5% and 1.5%, respectively vs 15.0%; P < .001 for both comparisons). Polyps <10 mm in size had a lower frequency of advanced histology compared with polyps ≥ 10 mm (0.8% vs 15.0%; P < .001). During sensitivity analysis, the frequency of advanced histological features varied from 0.2% to 0.7% within diminutive polyps, 1.5% to 3.6% within small polyps, and 0.8% to 1.2% within polyps <10 mm.

LIMITATIONS

Retrospective analysis from tertiary-care referral centers; predominantly white, male, veteran patient population resulting in limited generalizability of results.

CONCLUSION

The prevalence of advanced histological features in colon polyps ≤ 5 mm is very low (0.5%). This has important implications for the potential practice of "predicting, resecting, and discarding" diminutive colon polyps.

High resolution colonoscopy in a bowel cancer screening program improves polyp detection

AIM: To compare high resolution colonoscopy (Olympus Lucera) with a megapixel high resolution system (Pentax HiLine) as an in-service evaluation.

METHODS: Polyp detection rates and measures of performance were collected for 269 colonoscopy procedures. Five colonoscopists conducted the study over a three month period, as part of the United Kingdom bowel cancer screening program.

RESULTS: There were no differences in procedure duration (χ² P = 0.98), caecal intubation rates (χ² P = 0.67), or depth of sedation (χ² P = 0.64). Mild discomfort was more common in the Pentax group (χ² P = 0.036). Adenoma detection rate was significantly higher in the Pentax group (χ² test for trend P = 0.01). Most of the extra polyps detected were flat or sessile adenomas.

CONCLUSION: Megapixel definition colonoscopes improve adenoma detection without compromising other measures of endoscope performance. Increased polyp detection rates may improve future outcomes in bowel cancer screening programs.