The Prognostic Significance of Circulating Tumor DNA in Patients with Positive Lymph Node Disease after Robotic-Assisted Radical Cystectomy: A Contemporary Analysis

Background and objective Neoadjuvant therapy followed by radical cystectomy with lymphadenectomy remains the gold standard of treatment in patients with muscle-invasive bladder cancer. Pathologically positive lymph node (pN+) disease is known to convey a poor prognosis. Tumor-informed circulating tumor DNA (ctDNA) has emerged as a possible novel prognostic biomarker in the field. We seek to assess recurrence-free survival (RFS) for patients undergoing robotic-assisted radical cystectomy (RARC) with extended pelvic lymphadenectomy (ePLND) and to assess whether ctDNA status can be a prognostic marker for RFS outcomes in patients with pN+ disease. Methods Patients who underwent RARC + ePLND during 2015 to 2023 were included. A sub-group analysis (n = 109) of patients who had prospectively collected serial-longitudinal tumor-informed ctDNA analyses during 2021-2023 was performed. Survival analysis and Cox-regression models were conducted. Results Included were 458 patients with a median age of 69 (IQR 63–76), and a median follow-up time of 20 months (IQR 10-37). RFS for pN0 (n = 353) and pN+ (n = 105) at 12, 24 and 36 months were 87% vs. 54%, 80% vs. 39%, and 74% vs. 35%, respectively (log-rank, P < 0.0001). On Cox multivariate analysis ≥pT3 disease (Hazzard ratio [HR] = 3.36 [2.18–5.18], P < 0.001), pN+ disease (HR = 2.39 [1.55–3.7], P < 0.001), and recipients of neoadjuvant treatment (HR = 1.61 [1.11–2.34], P = 0.013) were predictive of disease relapse. Patients with pN+ disease and undetectable precystectomy or postcystectomy ctDNA status had similar RFS to patients with pN0 with undetectable ctDNA. On Cox-regression multivariate sub-group analysis, detectable precystectomy ctDNA status (HR = 3.89 [1.32–11.4], P = 0.014), detectable ctDNA status in the minimal residual disease window ([MRD], HR = 2.89 [1.12–7.47], P = 0.028), and having ≥pT3 with pN+ disease (HR = 4.2 [1.43–12.3], P = 0.009) were predictive of disease relapse. Conclusions Patients with pN+ .after RARC had worse oncological outcomes than patients with pN0 disease. Undetectable ctDNA status was informative of RFS regardless of nodal status at both the precystectomy and the MRD window. Patients with undetectable ctDNA status and pN+ disease may benefit from treatment de-escalation.