Comparing CxBladder to Urine Cytology as Adjunct to Cystoscopy in Surveillance of Non-muscle Invasive Bladder Cancer-A Pilot Study.

Guidelines advocate cystoscopy surveillance (CS) for non-muscle invasive bladder cancer (NMIBC) post-resection. However, cystoscopy is operator dependent and may miss upper tract lesions or carcinoma (CIS). Urine cytology is a common adjunct but lacks sensitivity and specificity in detecting recurrence. A new mRNA biomarker (CxBladder) was compared with urine cytology as an adjunct to cystoscopy in detecting a positive cystoscopy findings during surveillance cystoscopy in our center. Consented patients older than 18, undergoing CS for NMIBC, provide paired urine samples for cytology and CxBladder test. Patients with positive cystoscopy findings would undergo re-Trans Urethral Resection of Bladder Tumor (TURBT). Thirty-five patients were enrolled from April to June 2019. Seven contaminated urine samples were excluded. The remaining cohort of 23 (82%) and 5 (18%) females had a mean age of 66.69 (36-89). Eight (29%) patients with positive cystoscopy finding underwent TURBT. All 8 patients also had positive CxBladder result. This shows that CxBladder has a sensitivity and negative predictive value (NPV) of 100%, specificity of 75% and positive predictive value (PPV) of 62% in predicting a positive cystoscopy finding. TURBT Histo-pathological findings showed Low-grade Ta NMIBC in one patient (4%), and 7 (25%) patients had inflammatory changes. Urine cytology was only positive in one patient with a positive cystoscopy finding. This led to a sensitivity of merely 13% and NPV of 74%, while specificity and PPV was 100% in predicting a positive cystoscopy finding. CxBladder had high NPV and sensitivity which accurately predicted suspicious cystoscopy findings leading to further investigation. It has great potential for use as adjunct to cystoscopy for surveillance of NMIBC.