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Endoscopic scar assessment after colorectal endoscopic mucosal resection scars: when is biopsy necessary (EMR Scar Assessment Project for Endoscope (ESCAPE) trial)
  1. Pujan Kandel1,
  2. Eelco Christiaan Brand2,
  3. Joe Pelt1,
  4. Colleen T Ball3,
  5. Wei-Chung Chen1,
  6. Ernest P Bouras1,
  7. Victoria Gomez1,
  8. Massimo Raimondo1,
  9. Timothy A Woodward1,
  10. Michael B Wallace1
  11. the EMR SCAR Group
    1. 1 Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, Florida, USA
    2. 2 Department of Gastroenterology and Hepatology, University Medical Center Utrecht, Utrecht, The Netherlands
    3. 3 Division of Biomedical Statistics and Informatics, Mayo Clinic, Jacksonville, Florida, USA
    1. Correspondence to Dr Michael B Wallace, Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL 32224, USA; wallace.michael{at}


    Objective It is unclear whether endoscopic assessment of scars after colorectal endoscopic mucosal resection (EMR) has to include biopsies, even if endoscopy is negative. Vice versa, endoscopic diagnosis of recurrent adenoma may not require biopsy before endoscopic reinterventions. We prospectively analysed various endoscopic modalities in the diagnosis of recurrence following EMR.

    Design We conducted a prospective study of patients undergoing colonoscopy after EMR of large (≥20 mm) colorectal neoplasia. Endoscopists predicted recurrence and confidence level with four imaging modes: high-definition white light (WL) and narrow-band imaging (NBI) with and without near focus (NF). Separately, 26 experienced endoscopists assessed offline images.

    Results Two hundred and thirty patients with 255 EMR scars were included. The prevalence of recurrent adenoma was 24%. Diagnostic values were high for all modes (negative predictive value (NPV) ≥97%, positive predictive value (PPV) ≥81%, sensitivity ≥90%, specificity ≥93% and accuracy ≥93%). In high-confidence cases, NBI with NF had NPV of 100% (95% CI 98% to 100%) and sensitivity of 100% (95% CI 93% to 100%). Use of clips at initial EMR increased diagnostic inaccuracy (adjusted OR=1.68(95% CI 1.01 to 2.75)). In offline assessment, specificity was high for all imaging modes (mean: ≥93% (range: 55%–100%)), while sensitivity was significantly higher for NBI-NF (82%(72%–93%)%)) compared with WL (69%(38%–86%); p<0.001), WL-NF (68%(55%–83%); p<0.001) and NBI (71%(59%–90%); p<0.001).

    Conclusion Our study demonstrates very high sensitivity and accuracy for all four imaging modalities, especially NBI with NF, for diagnosis of recurrent neoplasia after EMR. Our data strongly suggest that in cases of high confidence negative optical diagnosis based on NBI-NF, no biopsy is needed to confirm absence of recurrence during colorectal EMR follow-up. A high confidence positive optical diagnosis can lead to immediate resection of any suspicious area. In all cases of low confidence, biopsy is still required.

    Trial registration number NCT02668198.

    • colonoscopy
    • endoscopic procedures

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    • Contributors Study concept and design: MBW, PK, W-CC and ECB. Acquisition of data and database preparation: PK and JP. Statistical analysis: PK, ECB and CTB. Interpretation of the results: all authors. Drafting of the manuscript: PK, ECB and MBW Critical revision of the article for important intellectual content: all authors. Study supervision: MBW. Final approval of the article: all authors.

    • Funding PK: Joyce E Baker Fund for Gastrointestinal Research at Mayo Clinic Florida. ECB received an unrestricted scientific internship abroad grant from the Dutch Digestive Foundation (16-03S).

    • Disclaimer Mayo Clinic does not endorse specific products or services included in this article.

    • Competing interests MBW reports consulting income from iLUmen and Interscope and grant support from Boston Scientific, Olympus, Medtronic and Cosmo pharmaceuticals.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Collaborators Group members and their affiliations are available in supplementary appendix 1.

    • Author note Portions of this manuscript have been published in abstract form: Kandel P, Brand EC, Chen WC, et al. 690 Diagnostic accuracy of optical detection of colorectal neoplasia after endoscopic mucosal resection: prospective double blind comparison of high definition white light, narrow band imaging and near focus. Gastrointest Endosc 2017;85:AB101–2. doi: 10.1016/j.gie.2017.03.149.

    • Correction notice This article has been corrected since it published Online First. The abstract and results section have been amended.

    • Presented at Presented at Digestive Diseases Week, Chicago, Illinois, 6–9 May 2017.

    • Patient consent for publication Not required.