Novel Optical Technology in Bladder Cancer Diagnosis and Treatment

Implication for health policy/practice/research/medical education: Novel optical imaging technologies have shown promising results for the diagnosis, management and follow up of bladder cancer. They might take the place of the white light cystoscopy which is the gold standard for many decades. Bladder cancer is diagnosed and followed-up with cys-toscopy as the " gold standard ". For many decades white light cystoscopy (WLC) has been used. However, several forms of bladder cancer such as the high-risk carcinoma in situ (CIS) may be misdiagnosed with WLC. As WLC still remains the cornerstone for the diagnosis of bladder cancer progress in endoscopic technology is warranted to improve the diagnostic accuracy of both rigid and flexible cystoscopy. Recently, photodynamic diagnosis (PDD) has been introduced for the diagnosis and transurethral resection of bladder cancer (TURBT), especially in cases of CIS (1). Photo-sensitizing drugs are intravesically administrated and are selectively accumulated in cancer cells, leading to the enhancement of contrast between benign and malignant bladder tissues. Prospective randomized studies have demonstrated that PDD improved bladder cancer detection, reduced residual tumor rates after TURBT, and prolonged the recurrence-free survival (1, 2). These studies have demonstrated the superiority of PDD-guided cys-toscopy over WLC in tumor detection, as the sensitivity for PDD was 76-97% compared to 46–80% for WLC (1, 2). Narrow band imaging (NBI) is a novel technique used in endoscopy to enhance tissue contrast between cancer-ous and normal bladder urothelium, while it does not require the administration of contrast agents (1). This technique is based on the phenomenon that the depth of light penetration into the urothelium increases when the wavelength is increased. In particular, NBI uses a light source that filters white light into two wavelengths (415 and 540 nm) which are strongly absorbed by hemoglo-bin, enhancing the contrast between subepithelial cap-illaries and mucosa (3). Prospective studies and meta-analyses have demonstrated that 10-25% cases of bladder cancer missed by WLC were detected by NBI (1, 4). Furthermore , NBI resulted in lower rates of residual bladder tumor during repeat TURBT and in reduced recurrence rates (4, 5). Optical coherence tomography (OCT) measures the backscattering of near-infrared light by tissue, and it yields in 2D and 3D images at micrometer-scale resolution , thus providing optical biopsies, approaching the resolution of histopathological imaging (6). It produces high-resolution, cross-sectional images of the bladder tissue enabling real-time bladder cancer staging (6). The principle of OCT is analogous to the B-mode …