Emerging optical techniques in advanced cystoscopy for bladder cancer diagnosis: A review of the current literature

The current standard for the diagnosis and followup of bladder cancer remains white light cystoscopy, despite its well-known limitations. The aim of this paper is to review the current literature on three optical diagnostics that have been developed to improve the performance of white light cystoscopy: photodynamic diagnosis, narrow-band imaging and optical coherence tomography. A PubMed search was performed for all articles on bladder cancer and photodynamic diagnosis, narrow-band imaging, and optical coherence tomography. Relevant papers on the working mechanism or clinical performance of the techniques were selected. Photodynamic diagnosis and narrow-band imaging both aim to improve the visualization of bladder cancer. Both techniques have demonstrated an improved detection rate of bladder cancer. For photodynamic diagnosis, decreased residual tumor rates and increased recurrence free survival after photodynamic diagnosis-assisted transurethral resection have been shown. Both techniques have a relatively high false positive rate. Optical coherence tomography is a technique aiming at real-time noninvasive pathological diagnosis. Studies have shown that optical coherence tomography can accurately discriminate bladder cancer from normal bladder mucosa, and even suggest that a reliable estimation of the stage of a bladder tumor can be made. Photodynamic diagnosis is the technique with most evidence of clinical effectiveness to date, but low specificity is limiting a widespread use. For the novelties, narrow-band imaging, and optical coherence tomography, more evidence is needed before these techniques can be implemented in daily urological practice