Predict, resect, and discard … really?

Optical Technologies for Endoscopic Real-Time Histologic Assessment of Colorectal Polyps: A Meta-Analysis

OBJECTIVES

Accurate, real-time, endoscopic risk stratification of colorectal polyps would improve decision-making and optimize clinical efficiency. Technologies to manipulate endoscopic optical outputs can be used to predict polyp histology in vivo; however, it remains unclear how accuracy has progressed and whether it is sufficient for routine clinical implementation.

METHODS

A meta-analysis was conducted by searching MEDLINE, Embase, and the Cochrane Library. Studies were included if they prospectively deployed an endoscopic optical technology for real-time in vivo prediction of adenomatous colorectal polyps. Polyposis and inflammatory bowel diseases were excluded. Bayesian bivariate meta-analysis was performed, presenting 95% confidence intervals (CI).

RESULTS

One hundred two studies using optical technologies on 33,123 colorectal polyps were included. Digital chromoendoscopy differentiated neoplasia (adenoma and adenocarcinoma) from benign polyps with sensitivity of 92.2% (90.6%-93.9% CI) and specificity of 84.0% (81.5%-86.3% CI), with no difference between constituent technologies (narrow-band imaging, Fuji intelligent Chromo Endoscopy, iSCAN) or with only diminutive polyps. Dye chromoendoscopy had sensitivity of 92.7% (90.1%-94.9% CI) and specificity of 86.6% (82.9%-89.9% CI), similarly unchanged for diminutive polyps. Spectral analysis of autofluorescence had sensitivity of 94.4% (84.0%-99.1% CI) and specificity of 50.9% (13.2%-88.8% CI). Endomicroscopy had sensitivity of 93.6% (85.3%-98.3% CI) and specificity of 92.5% (81.8%-98.1% CI). Computer-aided diagnosis had sensitivity of 88.9% (74.2%-96.7% CI) and specificity of 80.4% (52.6%-95.7% CI). Prediction confidence and endoscopist experience alone did not significantly improve any technology. The only subgroup to demonstrate a negative predictive value for adenoma above 90% was digital chromoendoscopy, making high confidence predictions of diminutive recto-sigmoid polyps. Chronologic meta-analyses show a falling negative predictive value over time. A significant publication bias exists.

DISCUSSION

This novel approach to meta-analysis demonstrates that existing optical technologies are increasingly unlikely to allow safe "resect and discard" strategies and that step-change innovation may be required. A "diagnose and leave" strategy may be supported for diminutive recto-sigmoid polyps diagnosed with high confidence; however, limitations exist in the evidence base for this cohort.

Digital Chromoendoscopy With i-Scan for In Vivo Prediction of Advanced Colorectal Neoplasia: A Multicenter Study

BACKGROUND

Recent studies have analyzed the potential of advanced endoscopic imaging techniques for differentiating hyperplastic and adenomatous colorectal lesions. Latest endoscopic resection techniques now also allow for treatment of more advanced staged lesions including treatment of early cancerous lesions.

AIMS

To assess the potential of the i-scan technology to differentiate between adenomatous polyps and advanced staged neoplasia.

METHODS

Consecutive patients undergoing colonoscopy at a tertiary referral center were included. After a dedicated training, participating endoscopists underwent a review of 298 unknown images of colonic lesions to assess colorectal lesion histology.

RESULTS

Overall accuracy for prediction of advanced staged neoplasia was 92.2% (sensitivity: 94.2%, specificity 90.9%). The positive and negative predictive values were calculated as 87.5% and 95.9%, respectively. The κ-value for differentiating adenomatous polyps and advanced staged neoplasia was 0.8193 (0.7894 to 0.8492). Intraobserver agreement was calculated with a κ-value of 0.9301 (0.8875 to 0.9727).

CONCLUSIONS

Accurate interpretation of i-scan images for prediction of advanced colorectal neoplasia can successfully be performed even by nonexpert endoscopists with a high overall accuracy and excellent interobserver agreements.

Suspicious macroscopic features of small malignant colorectal polyps

OBJECTIVE

The aim of this analysis was to retrospectively review video recordings of malignant polyps <10 mm in search for suspicious macroscopic features in white light endoscopy.

METHODS

Database entries and recordings of screening colonoscopies from a single tertiary referral center between June 2009 and December 2012 were reviewed. Malignant polyps <10 mm were analyzed. The recordings were reviewed by two expert endoscopists in search for suspicious morphological features: irregular contours, central depression, contact bleeding, shape deformity, central depression, chicken skin sign, circumscribed area with abnormal vascular and/or surface pattern. Then, six experienced endoscopists watched the recordings in search of listed features. Next, video recordings of these malignant polyps were mixed with randomly drawn video recordings of 20 non-malignant polyps matched by size and reviewed by 14 blinded endoscopists to assess the sensitivity and specificity for the diagnosis of malignant polyps.

RESULTS

Five of the 8651 (0.06%) subjects who underwent screening colonoscopy during the study period were diagnosed with a malignant polyp <10 mm. Only one of them was ad hoc identified by performing endoscopist as suspicious. On recordings review performed by the experts, each of the four remaining polyps presented at least one suspicious macroscopic feature. Presence of these features was confirmed by experienced endoscopists. The sensitivity and specificity for the diagnosis of malignant polyp were 73.21% and 85.35%, respectively, if at least two suspicious macroscopic features defined malignant polyp.

CONCLUSIONS

On careful white light endoscopy examination small malignant colorectal polyps show suspicious macroscopic features, which were frequently unrecognized by examining endoscopists.

Optical diagnosis of small colorectal polyps during colonoscopy: when to resect and discard?

Colonoscopy with polypectomy has been shown to be effective in reducing incidence and mortality from colorectal cancer (CRC). The increase in use of colonoscopy in national bowel cancer screening programmes combined with improved technology has resulted in a large increase in detection of polyps. Most polyps detected at screening colonoscopy are small (<10 mm) or diminutive (<6 mm) and, in particular the latter, have a very small chance of containing advanced features or cancer. The main reason for resecting small adenomas and sending them to histopathology serves to inform on the future surveillance intervals. Being able to diagnose adenomas in vivo would allow for them to be resected and discarded, saving the costs associated with histopathology. Diagnosing distal hyperplastic polyps in vivo would allow for these to be left in situ reducing the risks associated with polypectomy. There are now a number of new technologies that could potentially make optical diagnosis a reality. Resect and discard policy is an attractive concept for patients, gastroenterologists and health service providers and would present an enticing change to current clinical practice.

New paradigms in polypectomy: resect and discard, diagnose and disregard

Polypectomy at colonoscopy has been shown to reduce the subsequent risk of colorectal cancer. With the advent of national screening programs, the number of colonoscopies performed has increased worldwide. In addition, the recent drive for quality improvement combined with advances in colonoscopic technology has resulted in increased numbers of polyps detected, resected, and sent for histopathology leading to spiraling costs associated with the procedure. Being able to diagnose small polyps in vivo (optical diagnosis) would allow for adenomas to be resected and discarded without the need to retrieve them or send them for formal histopathology.

Learning curve of virtual chromoendoscopy for the prediction of hyperplastic and adenomatous colorectal lesions: a prospective 2-center study

BACKGROUND

Computed virtual chromoendoscopy (CVC) enables high-definition imaging of mucosal lesions with improved tissue contrast. Previous studies have shown that CVC yields an improved detection rate of colorectal lesions. However, the learning curve for interpretation of CVC images is unknown.

OBJECTIVE

To examine the learning curve of correctly identifying hyperplastic and adenomatous colorectal lesions by using CVC.

DESIGN

Prospective, 2-center study.

PATIENTS

Consecutive patients undergoing screening colonoscopy were included. CVC images were analyzed by using corresponding polypectomies as the reference standard followed by a prospective, double-blind review of i-scan images.

METHODS

A training set containing 20 images with known histology was reviewed to standardize image interpretation, followed by a blind review of 110 unknown images. Overall, 4 endoscopists from 2 different endoscopy centers evaluated the images, which were obtained by 1 endoscopist using high-definition endoscopy with CVC.

RESULTS

Patients were included in a prospective fashion. Seventy-seven of 110 colorectal lesions were adenomas and 33 were hyperplastic lesions. Mean diameter of colonic polyps was 4 mm (range, 2-20 mm). Overall accuracy for the group was 73.9% for lesions 1 to 22, 79.6% for lesions 23 to 44, 84.1% for lesions 45 to 66, 87.5% for lesions 67 to 88, and 94.3% for lesions 89 to 110. Accuracy of i-scan for prediction of polyp histology was not dependent on polyp size (≤5 mm, 6-10 mm, or > 10 mm). The ability to obtain high-quality images was stable over time, and high-quality images were constantly produced.

LIMITATION

Post-hoc assessment.

CONCLUSION

Accurate interpretation of CVC images for prediction of hyperplastic and adenomatous colorectal lesions follows a learning curve but can be learned rapidly.

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.