Clinical Utility of Ureteral Optical Coherence Tomography for T Staging of Ureteral Cancer: NOCTURN Study

<b><i>Objectives:</i></b> One of the major limitations of the current diagnostic techniques for upper urinary tract carcinoma (UTUC) is the risk of both understaging and overstaging, highlighting the need for real-time, high-resolution intraoperative imaging. We evaluated the diagnostic accuracy and safety of ureteral optical coherence tomography (OCT) under ureterorenoscopy for T staging of UTUC. <b><i>Materials and Methods:</i></b> In this study, patients with suspected UTUC were prospectively enrolled. The safety analysis set included 16 patients who underwent ureteral OCT for ureteral tumors. Because two (13%) patients underwent ureterorenoscopic ablation therapy, the diagnostic accuracy analysis set included 14 of 16 patients who had both ureteral OCT data and a final pathological T (pT) stage from surgical specimens. The concordance, underdiagnosis, and overdiagnosis rates were compared between radiographical imaging-based T (cT) and OCT-based T (octT) diagnoses. The primary outcome was the diagnostic accuracy of ureteral OCT in discriminating between pTis/Ta/T1 (non-muscle-invasive UTUC) and T2/T3 (muscle-invasive UTUC) cancers. <b><i>Results:</i></b> Concordance between cT-based and pT-based diagnoses was observed in 11 (79%) of the 14 patients, whereas a higher concordance rate (13/14, 93%) was noted for octT diagnosis. Additionally, the underdiagnosis and overdiagnosis rates of octT were 0% and 7.1%, respectively, which were lower than those of cT (7.1% and 14%, respectively). Although no intraprocedural urinary injury was observed, postprocedural complications included hematuria in five patients (31%), urinary tract pain in two (13%), and urinary tract infection in one patient (6.3%). <b><i>Conclusion:</i></b> Ureteral OCT exhibited a high diagnostic performance in discriminating between non-muscle-invasive UTUC and muscle-invasive UTUC with a safety profile. Further prospective trials with large sample sizes are necessary to determine the true diagnostic value and the wide use of ureteral OCT.