Background: Patients with ulcerative colitis and Crohn's colitis have increased risk of colorectal cancer. Current screening endoscopy protocols based on white light endoscopy (WLE) and random biopsies are laborious and of uncertain sensitivity. Novel endoscopic techniques include chromoendoscopy (CE) and confocal laser endomicroscopy (CLE).
Aim: The aim was to compare WLE and CE for the detection of intraepithelial neoplasia (IEN). Furthermore, we analysed the sensitivity and specificity of CE and CLE for the diagnosis of IEN.
Methods: The cohort consisted of 30 patients examined by WLE, CE with 0.4% indigocarmine, and by a CLE system Pentax EC-3870CIFK during one examination. Additional 15 patients were examined by conventional protocol only. Random biopsies and biopsies from all suspicious lesions were taken. We compared the number of IENs detected by WLE and CE and analysed the predictive values of CE and CLE for the histology diagnosis.
Results: There were 1584 random biopsies (35.2 per patient) taken. There were 78 targeted biopsies (1.7 per patient) taken in 24 of 45 patients examined by WLE and an additional 36 biopsies in 16 of 30 patients examined by CE (1.17 additional per patient). There were no IENs found on random biopsies versus six low-grade or high-grade IENs in four patients (two detected by WLE, four additional by CE) from targeted biopsies, P=0.02. A total of 100 suspicious lesions were detected and analysed by CE and histology. CLE could not examine 32 of 100 lesions (two of 30 flat vs. 30 of 70 pedunculated lesions, P=0.0002, odds ratio 10.5). The sensitivity of CE/CLE for low-grade or high-grade IEN was 100/100%, the specificity 96.8/98.4%, positive predictive value was 62.5/66.7% and negative predictive value was 100/100%.
Conclusion: Targeted biopsies are superior to random biopsies in the screening of IEN in patients with inflammatory bowel disease. CE increases the diagnostic yield of WLE. In our study CLE did not provide additional clinical benefits.