New imaging tools in the diagnosis and management of superficial bladder cancer have in recent years emerged, but their potentials have yet to be proven with strong data, according to Prof. Gunter Janetschek (AT) who spoke at the second-day session of the 10th South Eastern European Meeting in Belgrade.
He listed the array of current imaging tools such as white light cystoscopy (WLC), photodynamic diagnosis (PDD), Narrow Band Imaging (NBI), Storz professional image enhancer system (SPIES), Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE), the latter being the most recent.
In his overview lecture, Janetschek compared PDD with White Light-TURBT and said that only 32% of CIS are detectable with PDD.
According to Janetschek, current literature show that fluorescence cystoscopy improves the rate of CIS detection. and that fluorescence-guided TURBT decreasez the likelihood of leaving behind residual tumour (Evidence Grade B). He also mentioned that fluorescence cystoscopy can be used in the examination of patients with positive findings on voided cytology but with negative findings on WLC imaging (Grade C).
Regarding NBI, Janetschek examined the procedure as he reviewed the main properties and capabilities of NBI such as the reflection, absorption and scattering of light, and mentioned that white light has a clear limitation in creating contrast of vessels due to surrounding tissues.
NBI, explained Janetschek, has detection rates of around 79% to 94% and detects 13% more tumours at second TUR. Tumour recurrence is thus reduced but CIS detection is better with PDD.
In a trial study of 960 patients (De La Rosette et al) that compared NBI with WL cystoscopy Janetschek noted the results showed no difference in the 12 months in terms of recurrence-free survival and that the only difference in favour of NBI was observed in the low-risk group of patients.
He also mentioned new perspectives with regards to the emergence of SPIES which can enhance structural changes, that are well defined in white light, but appear in SPIEs Mode with more contrast. On the other hand, PDD offers tumour-specific information and that changes that are not visible in white light become visible in PDD Mode.
With regards to OCT, he said OCT uses safe near infrared light and measures backscattered light. With approximately 1.6 to 2mm tissue penetration, majority of epithelial cancers can be identified with OCT. Moreover, the technique has higher resolution than ultrasound (10-100X ultrasound). But there is a challenge to OCT performance such as the question on probe placement and the time-consuming procedure. Also, the question arises whether combining PDD with OCT will lead to better clinical outcome compared to OCT alone.
“OCT aim at providing a real-time, minimally invasive, objective prediction of histopathologic diagnosis, while PDD and NBI aim at improving visualisation of bladder tumours,” said Janetschek.
“For OCT more research has to be conducted before these techniques can be implemented in daily practice,” he added.
Finally, he assessed the benefits or prospects in CLE and mentioned that it serves as a sort of optical biopsy. He also expressed optimism that CLE in the future may further undergo refinements for it to present better alternatives than standard tools being used today.
In his concluding remarks, he noted that PDD remains the standard tool by far, and the new tools such SPIES, although easily available and with enhanced vision, still has missing data, with its value still unclear. CLE, on the other hand, is still experimental but has potentials in combination with PDD/NBI/SPIES.