Adding Narrow-Band Imaging to Chromoendoscopy for the Evaluation of Tumor Response to Neoadjuvant Therapy in Rectal Cancer.

BACKGROUND Endoscopic assessment is crucial in diagnosing clinical complete response after neoadjuvant therapy in rectal cancer. OBJECTIVE To evaluate the benefits of adding narrow-band imaging endoscopy to conventional chromoendoscopy in predicting pathological complete response in the surgical specimen. DESIGN Prospective nonrandomized study SETTINGS:: This was an ad hoc study of a prospective phase II trial at a single comprehensive cancer center that evaluated oncological outcomes of a neoadjuvant therapy for rectal cancer. PATIENTS Patients with high-risk stage II-III low rectal cancer who received neoadjuvant modified folinic acid, fluorouracil, and oxaliplatin plus bevacizumab followed by chemoradiotherapy and surgery. INTERVENTION Tumor response after neoadjuvant therapy was evaluated using conventional white light endoscopy plus chromoendoscopy then followed by using narrow-band imaging based on a predefined diagnostic protocol. MAIN OUTCOME MEASURES Diagnostic accuracy for predicting pathological complete response and inter-rater agreement between an expert and trainee endoscopists were compared between the assessments using conventional white light endoscopy plus chromoendoscopy and the assessment adding narrow-band imaging. RESULTS In total, 61 patients were eligible for the study, and 19 had pathological complete response (31.1%). Although the addition of narrow-band imaging correctly converted the diagnosis in 3 patients, overall diagnostic improvement in predicting pathological complete response was limited (conventional chromoendoscopy vs adding narrow-band imaging: accuracy, 70.5% vs 75.4%; sensitivity, 63.2% vs 73.7%; specificity, 73.8% vs 76.2%; positive predictive value, 52.2% vs 58.3%; and negative predictive value, 81.6% vs 86.5%). A kappa value for the inter-rater agreement improved from 0.599 to 0.756 by adding narrow-band imaging. LIMITATIONS A single-center study with a relatively small sample size. CONCLUSIONS Despite the limited improvement in diagnostic accuracy, adding narrow-band imaging to chromoendoscopy improved inter-rater agreement between the expert and non-expert endoscopists. Narrow-band imaging is a reliable and promising modality for universal standardization of the diagnosis of clinical complete response. See Video Abstract at http://links.lww.com/DCR/B275.