Impact of micropapillary urothelial carcinoma variant histology on survival after radical cystectomy

Objectives: The role of micropapillary urothelial carcinoma (MUC) variant histology as an independent prognostic factor for survival after radical cystectomy has not been studied. Our aim was to examine the impact of MUC on survival. Materials and methods: A retrospective analysis of prospectively collected data from the University of Southern California (USC) Bladder Cancer Database was performed. Between 1985 and 2008, 1,380 patients underwent radical cystectomy and superextended pelvic lymph node dissection for bladder cancer. All surgical specimens underwent central pathologic review by dedicated genitourinary pathologists. Histologic type was categorized as urothelial carcinoma (UC; n = 1,347) or MUC (n = 33). The outcomes were overall survival (OS) and recurrence-free survival (RFS). The Kaplan-Meier method and Cox proportional regression models were used to analyze survival data. Results: The median follow-up duration was 10 years (range, 0-25 years). Baseline characteristics were similar between histologic types except MUC was associated with advanced clinical (cTanyN1-3: 2% vs. 9%, P = 0.03) and pathologic (pTanyN1-3: 22% vs. 46%, P = 0.01) TNM stage, multifocality (38% vs. 58%, P = 0.02), and high nuclear grade (83% vs. 97%, P = 0.03). The predicted 5-year OS (61% and 67%, Log rank P = 0.96) and RFS (69% and 58%, Log rank P = 0.33) rates did not differ between patients with UC and MUC. Multivariable analysis showed that histologic type was not independently associated with OS (HR 0.91, 95% CI 0.55-1.49, P = 0.70) or RFS (HR 0.97, 95% CI 0.55-1.73, P = 0.92). Conclusions: Outcomes of radical cystectomy for patients with MUC are similar to those with UC when controlling for other clinical and pathologic factors. (C) 2014 Elsevier Inc. All rights reserved.