Review of current optical diagnostic techniques for non-muscle-invasive bladder cancer

Urinary bladder urothelial cell carcinoma is one of the most commonly diagnosed cancers in Europe. After prostate, lung and colon cancers, bladder cancer rates as the fourth most common cancer in men in the world. Urinary bladder cancer detection, treatment, and staging have traditionally been based on an endoscopic examination - cystoscopy.

A Medline, and Web of Science database search was performed on September 2015 without setting time limits, using the terms 'bladder cancer' in conjunction with 'cystoscopy', 'diagnosis', 'detection', 'fluorescence', 'blue-light', 'PDD', 'narrow band imaging', 'molecular imaging', 'optical coherence tomography' or 'confocal laser endomicroscopy'.

The new imaging techniques can be classified according to their scope as macroscopic, microscopic, and molecular. Macroscopic techniques, such as narrow band imaging, are similar to white light cystoscopy; however, they help visualize even very minute lesions in the bladder mucosa by means of contrast enhancement. Microscopic imaging techniques, such as optical coherence tomography and confocal laser endomicroscopy, provide high-resolution cross-sectional views of vesicular tissues, which resemble images obtained by histopathological examination. Therefore, these are referred as 'optical biopsy'. Molecular imaging methods offer highly specific real-time visualization of cancer cells and their differentiation from healthy tissue, by combining optical imaging with fluorescent labeling of elements such as antibodies.

In this article we present a review of studies and literature concerning modern optical diagnostic techniques for non-muscle-invasive bladder cancer. We present available technology with its advantages and disadvantages, and studies regarding its effectiveness.