Flexible cystoscopy using narrow-band imaging (NBI) is more effective in detecting non-muscle-invasive bladder cancer than is traditional cystoscopy using white light, researchers stated at the 2010 American Urological Association (AUA) Annual Meeting.
Endoscopic narrow-band imaging is routinely used around the world to assess gastrointestinal abnormalities, explained Yi-Jun Shen, MD, Fudan University Hospital, Shanghai, China. Comparisons with bladder cancer also echo superiority for NBI, Dr. Shen noted, speaking here at a poster presentation on June 1. "NBI is clearly more effective to detect new non-muscle-invasive [bladder cancer] than white light, just like it is in gastrointestinal use," Dr. Shen stated.
The debate over white-light cystoscopy versus narrow-band imaging comes down to observer bias, Dr. Shen explained. Most prior studies in non-muscle-invasive bladder cancer have utilised the same urologist viewing the same images under white light and narrow-band illumination, which raises questions of reliability and utility in the broader urologist population.
Dr. Shen designed a study using a randomised sequence of images taken using white light and narrow-band imaging to compare detection rates of new cases of non-muscle-invasive bladder cancer under the different illumination sources.
Flexible cystoscopy using the same Olympus Lucera sequential endoscopy system was used to image 45 bladders with suspected new cases of non-muscle-invasive bladder cancer using both narrow-band imaging and white light imaging. All 45 patients were examined between February and October 2009. Images were shown to observers in a predetermined, random order for a set length of time to eliminate any potential observer bias.
A total of 110 biopsies were performed under white light and 142 under narrow-band imaging. Biopsies obtained by both white light and narrow-band imaging were examined separately by an experienced pathologist. After biopsy, a standard transurethral resection (TUR) with resected samples was performed to confirm the presence of tumours.
Within the group of 45 patients, 41 (91.1%) had confirmed non-muscle-invasive bladder cancer. Of the patients with tumours, 33 were detected by both white light and narrow-band imaging, 0 were seen only by white light, 7 were seen only by narrow-band imaging, and 1 was missed by both white light and narrow-band imaging.
A total of 110 biopsies were taken under white light, with 89 showing signs of cancer. A total of 142 narrow-band imaging biopsies were taken, with 113 showing signs of cancer. The sensitivity of white light imaging was 80.5% compared with 97.6% for narrow-band imaging (P < .05); the specificity was 50% and 75%, respectively (P < .05), and accuracy was 77.8% versus 95.6% (P < .05).
Dr. Shen reported that all 5 T1 cancers found on TUR were identified on narrow-band imaging, while white light imaging missed 2 T1 cancers. Narrow-band imaging detected 24 cancerous lesions in 15 patients that were missed by white light imaging.
"What we found was that anyone can use NBI efficiently and effectively in bladder cancer, even residents, after just a short learning curve," Dr. Shen noted. "We have found that it only takes 20 or 30 images for a new user to become proficient in this technique."