Predictors and outcomes of pT0 histology at radical cystectomy in patients with bladder cancer.

Abstract

Introduction & Objectives: No residual tumour at radical cystectomy, denoted as pT0, occurs at a rate of approximately 5-20% in the literature. This may be related to completeness of TURBT or neoadjuvant chemotherapy (NAC), which may result in a complete local response. Although no residual tumour (or pT0) is known to confer survival benefit, there is still risk of recurrence in these patients. As yet there is no Australian data reporting outcomes of patients who achieve no residual tumour (pT0) at radical cystectomy (RC). This study aims to assess the predictors of pT0 histology at RC for bladder cancer, and assess the survival benefit conferred by achieving pT0. Method(s): 158 patients who underwent RC at our tertiary centre, from 2010 to 2023 were analysed retrospectively, following QA ethics approval by the local HREC. Predictors of pT0 histology at cystectomy were analysed via multivariate logistic regression. Kaplan-Meier analysis was performed to assess survival/event-free probability with regards to overall survival (OS), cancer-specific survival (CSS), and recurrence free survival (RFS) in patients who had no residual tumour at cystectomy (pT0) compared to those who had residual bladder cancer on the cystectomy specimen. Cox proportional hazards regression was utilised to assess predictors of OS, CSS and RFS. Result(s): Via multivariate logistic regression, using variables of age, gender, MIBC at TURBT, NAC and variant histology - only NAC was predictive of pT0 histology at RC (OR 5.39, 95% CI 1.43-19.3, P = 0.01), while age (OR 0.99, 95% CI 0.95-1.05, P = 0.8), gender (males: OR 0.91, 95% CI 0.25-4.35, P = 0.9), MIBC at TURBT (OR 0.54, 95% CI 0.17-1.89, P = 0.3) and variant histology (OR 0.63, 95% CI 0.03-3.63, P = 0.7) were not statistically significant. Via Kaplan-Meier analysis and log-rank test, those with pT0 histology at RC had significantly greater OS (P = 0.0021), CSS (P = 0.036), and RFS (P = 0.01). This association persisted after multivariate adjustment. Via Cox proportional hazards model, after multivariate adjustment for age, gender, NAC, and variant histology - pT0 histology was associated with significantly lower risk of overall mortality (OR 0.08, P = 0.0146), cancer-specific mortality (OR 0.13, P = 0.04997), and recurrence (OR 0.23, P = 0.0174). Conclusion(s): In our Australian cohort, the only significant predictor of no residual tumour (pT0) at RC for bladder cancer was whether patients received NAC. In concordance with international literature, pT0 histology at RC was associated with greater overall survival, cancer-specifical survival and recurrence-free survival, even after adjustment for factors such as age, gender, MIBC on TURBT histology, NAC and variant histology. Our results demonstrate the importance of ensuring patients receiving standard-of-care NAC, and the importance of maximal TURBT, due to the survival benefit conferred by pT0 histology at RC.