To clarify the clinical utility of urinary DNA methylation for detection of intravesical recurrence of non-muscle invasive BCa (NMIBC), we performed a 2 center prospective study.

A series of 207 self-voided urine samples were prospectively collected from 132 NMIBC patients who had undergone transurethral resection of BCa. Methylation of miRNA genes (miR-9-3, miR-124-2, miR-124-3 and miR-137) was analyzed using bisulfite pyrosequencing. The primary endpoint was detection of intravesical recurrence; the secondary endpoint was prediction of late recurrence. The number of methylated genes (M-score) and/or quantitative level of methylation were compared with outcomes.

Twenty six urine specimens were collected on the same day intravesical recurrence was detected, and 14 were collected from patients whose recurrences were found during the subsequent follow-up period (0 - 632 days, mean, 342.2 days). For detection of current recurrence, M-scores achieved 61.5% sensitivity and 74.0% specificity, and the area under the ROC curve was 0.71. Regarding prediction of late recurrence, patients with a high M-score (≥ 3) showed worse recurrence-free survival (P < 0.01). Multivariate analysis revealed that high M-scores were independently associated with current (P = 0.028) and late recurrence (P = 0.026). Elevated levels of urinary DNA methylation were also strongly associated with recurrence and radical cystectomy.

Our data suggest that urinary methylation of miRNA genes may be a useful marker for detecting and predicting BCa recurrence.