Abstract
BACKGROUND: High-risk non-muscle invasive bladder cancer (HR-NMIBC) patients require long-term surveillance with cystoscopies, cytology and upper tract imaging. Previously, we developed a genomic urine assay for surveillance of HR-NMIBC patients with high sensitivity and anticipatory value. OBJECTIVE: We aimed to validate the performance of the assay in an unselected prospectively collected cohort of HR-NMIBC patients under surveillance. METHODS: We included patients from five centers and collected urine sample pairs (evening and morning urines) prior to cystoscopy. Mutation status (FGFR3/TERT) and methylation status (OTX1) was analyzed on DNA from voided urine specimens. A test was considered positive if≥1 alteration was detected in at least one urine sample. The primary endpoint was tumor recurrence. Sensitivity and specificity were determined. A generalized mixed effects model was used to adjust for within-patient correlation. Cox proportional hazard analyses with time-dependent covariates assessed the anticipatory effect of the urine assay. RESULTS: In total, 204 patients and 736 sample pairs were collected. Sixty-three recurrences were diagnosed for which we had concomitant assay results. On cross-sectional analyses, the assay detected 75% (95% CI 62.1% -84.7%) of recurrences, with a specificity of 70% (95% CI 66.4% -73.5%). Furthermore, mixed effects model analyses revealed OTX1 (p = 0.005) and TERT (p = 0.004) as significant predictors for disease recurrence. Median follow-up was 25.3 months (IQR 18.6-30.7). Twenty-nine tumors were diagnosed without concomitant urine samples, which included recurrences detected after urine collection ended. Longitudinal analyses showed that a positive urine assay predicted a recurrence over time (HR 3.5, p < 0.001). Furthermore, a recurrence during the study period was also a predictor for developing future recurrences (HR 2.1, p < 0.001). CONCLUSIONS: This study validates the performance of a previously developed urine assay in an unselected cohort of HR-NMIBC patients under surveillance. With a robust sensitivity/specificity and a strong anticipatory effect, this assay proves a useful adjunct ready for evaluation in a future randomized controlled trial.