Mieke Bus

5 69 Introduction Though radical nephroureterectomy (RNU) is still treatment of choice of upper urinary tract urothelium carcinoma (UTUC), nephron sparing surgery emerges as a viable option in selected patients. (1) In this setting, tumor grading and staging are inevitable in order to prevent recurrence or progression and to maintain the opportunity of curative surgery. Diagnosis of UTUC is based on imaging, ureterorenoscopy (URS) and cytology/histology. (1) Unfortunately these techniques have several limitations. No real-time intra-operative histo- logical information is obtained on stage and grade using imaging. Histopathological diagno- sis obtained during URS is often inconclusive due the difficulty of tissue sampling. The small biopsy samples result in absence of malignant cells, distorted architecture or absence of muscular layer leading to a high rate of tumor upgrading/upstaging when compared with nephroureterectomy specimens. (2, 3) If reliable grading and staging can be obtained during URS, better patient selection for endoscopic treatment will be made. Optical Coherence Tomography (OCT) is a high resolution imaging technology that can be applied during URS and is analogous to ultrasound. It uses backscattered light instead of back reflected sound waves to produce cross-sectional images and has the potential to provide real-time infor- mation on grade and stage in UTUC, as previously demonstrated in a pilot study. (4) Although this pilot study demonstrated the potential of OCT in the diagnosis of grade and stage in UTUC, no information on diagnostic accuracy of OCT was given. The primary aim of this study was to assess the diagnostic accuracy of OCT and biopsy in determining grade and stage of UTUC. Second, we aimed to evaluate the sensitivity and specificity of OCT and biopsy in the diagnosis of UTUC. We carried out this study in the context of the second stage (2a and 2b) of the IDEAL model, designed for evaluating new surgical innovations (1 Innovation/Idea, 2a Development, 2b Exploration, 3 Assessment, 4 Long-term follow-up) and the STARD initiative. (5-7) Material & Methods Power calculation One Way Anova sample size calculation was performed using nQueri advisor7.0 using as input the attenuation values from our first in-vivo pilot by Bus et al. (#treatment or groups = 4, CSS of Means = 3.3, SD = 2.1). (4) The calculated power of 95% resulted in a sample size of twenty-six patients. Inclusion and protocol Consecutive patients with clinical suspicion or follow-up of UTUC were included in a pro- spective study assessing the diagnostic accuracy of OCT in the staging and grading of UTUC. The study was approved by the institutional Medical Ethical Committee of our hospital and informed consent was required and obtained from all patients