Urovysion: Considerations on modifying current evaluation scheme, including immunophenotypic targeting and locally set, statistically derived diagnostic criteria.

Urovysion multitarget fluorescence in situ hybridization (FISH) assay is a promising tool for detection of bladder cancer, however, there is still no consensus regarding abnormal signal pattern and cut-off level, and the recommended targeting carries limitations similar to urine cytology. Aim of this study was to explore diagnostic benefits of a recently introduced method featuring target specific genotyping, as well as to investigate the feasibility of locally and statistically determined cut-off, compared with conventional evaluation scheme. Histology, cytology, and comparative FISH approaches were performed on 42 patients with high clinical suspicion for urothelial carcinoma (UC). FISH parallels were (1) Urovysion-alone (according to manufacturer's instruction); (2) Targeted-Urovysion (cytokeratin7 immunophenotyping followed by Urovysion), both of which evaluated by both conventional and statistical evaluation scheme. For statistical evaluation cut-offs and sufficient sample size were determined on controls and ratio of positive cells was recorded, whereas conventional evaluation relied on manufacturer's recommendations. The specificity of cytology, Urovysion-alone in general and targeted-Urovysion in general appeared 86%, 86%, and 100%, respectively. In the same comparison, overall sensitivity was 60%, 80%, and 93%, respectively. In superficial cases sensitivity was 48% for cytology, 72% for Urovysion-alone and 91% for targeted-Urovysion, while no prominent differences were seen in muscle invasive cases. The ratio of FISH positive cells was proportionate with both stage and grade, however, targeted genotyping could separate high grade/high stage cases more effectively. In conclusion, CK7 targeting raises diagnostic efficiency of Urovysion, and could be an ideal tool for identifying tumor cells in ambiguous cases or when other tumors are present. Statistical evaluation produces accuracy comparable with results of conventional evaluation, and with laboratories setting cut-offs individually but according harmonized protocol, it could aid method standardization. Furthermore, by providing additional quantitative information about tumor characteristics, is likely to have therapy relevant value in the future.