A New Tool for Distinguishing Muscle Invasive and Non-Muscle Invasive Bladder Cancer: The Initial Application of Flexible Ultrasound Bronchoscope in Bladder Tumor Staging

OBJECTIVES To validate the flexible ultrasound bronchoscope (FUB) as a tool in distinguishing muscle invasive and non-muscle invasive bladder tumors. MATERIALS AND METHODS From June 2010 to April 2012, 62 patients (11 female and 51 male) with 92 bladder urothelial carcinoma were treated in our study. The mean (±SD) patient age was 64.0±12.5 years old (ranged from 22 to 87). Clinical T stage was assessed by FUB at first in operating room, then immediately initial diagnostic transurethral resection (TUR) was performed. A second TUR would be done 2-4 weeks after initial TUR when the latter was incomplete (in large and multiple tumours, no muscle in the specimen) or when an exophytic high-grade and/or T1 tumour was detected. And radical cystectomy would be performed for the patients who were diagnosed with muscle-invasive tumors. FUB staging and initial TUR staging, final pathological results were compared. RESULTS In ultrasonic images, the normal muscle layer of bladder wall could be clearly distinguished into three layers, which were hyperechogenic mucosa, hypoechogenic muscle and hyperechogenic serosal. For non-muscle invasive tumors, the muscle layers were continuous. And distorted or discontinuous muscle layers could be seen in muscle-invasive case. The overall accuracy (95.7%) and the specificity of muscle invasion detection of FUB (98.8%) were comparable to TUR (overall accuracy 90.2% and specificity 100%), but sensitivity of muscle invasion detection of FUB was significantly higher than initial TUR (72.7%VS18.2%). Moreover, the tumor's diameter could not affect the FUB's accuracy of muscle invasion detection. For tumors near the bladder neck, FUB also showed the similar validity as those far from bladder neck. CONCLUSIONS To conclude, the flexible ultrasound bronchoscope is an effective tool for muscle invasion detection of bladder tumor with ideal ultrasonic images. It is an alternative option for bladder tumor staging besides TUR. It might have the potentiality to change the bladder diagnostic strategy.