Narrow-band imaging flexible cystoscopy in the detection of primary non-muscle invasive bladder cancer: a second look matters?

Objective We investigated whether narrow-band imaging (NBI) was superior to white light imaging (WLI) for detecting primary non-muscle invasive bladder cancer (NMIBC) in a randomized imaging sequence modality, as the increased detection rate by NBI maybe result from the second look'' inspection of the bladder. Methods Between February 2009 and May 2010, NBI and WLI flexible cystoscopy were prospectively performed on 78 patients with primary suspected NMIBC. According to randomization protocol, the bladder was mapped using WLI then NBI or vice versa within the same observation time. Suspicious lesions together with controlled normal-appearing mucosa were biopsied and examined by a pathologist blinded to the imaging sequence. The tumors detected on patient and tumor level, sensitivity, specificity, and accuracy were compared in both imaging. Results Sixty-nine of 78 (88.5%) patients were diagnosed with bladder cancer including 211 tumors totally. Of these, 36 (17.1%) tumors in 13 patients were detected by NBI only, while 4 (1.9%) tumors in 3 patients found by WLI only. NBI identified significantly more additional tumors than WLI (P < 0.01). The sensitivity of WLI versus NBI for detecting primary bladder tumors was 77.7 versus 92.9% (P < 0.0001), the specificity 82.7 versus 73.5% (P > 0.05), and the accuracy 79.3 versus 86.7% (P < 0.05). The sensitivity of WLI versus NBI for detecting carcinoma in situ (CIS) was 68.3 versus 87.8% (P < 0.05), the specificity 82.9 versus 77.1% (P > 0.05), and the accuracy 75 versus 82.9% (P > 0.05). Conclusions The second look'' did not compromise the superiority of NBI over standard WLI flexible cystoscopy for detecting primary NMIBC including CIS lesions.