Risk group stratification in patients with micropapillary bladder cancer treated with radical cystectomy and/or neoadjuvant chemotherapy.

302 Background: Micropapillary bladder cancer (MPBC) is an aggressive variant of urothelial carcinoma. We have previously published clinical risk stratification groups for patients with conventional urothelial carcinoma and sought to identify if these were valid in patients with this variant histology. Methods: An IRB approved review of 1910 patients in our radical cystectomy database revealed 106 patients with preoperative diagnosis of ≤cT4aN0M0 MPBC between December 1992 and January 2012 who underwent upfront radical cystectomy (RC, n = 74) or neoadjuvant chemotherapy (NAC) followed by RC (n = 32). To determine whether patients with MPBC can be risk stratified using traditional risk factors, a recursive partitioning analysis (RPA) was performed. Results: In multivariate analyses, hydronephrosis (HR=3.1; p=0.01), and extent of MPBC at transurethral resection (TUR) (HR=1.9; p=0.04) were associated with shortened OS. In the reduced model, clinical stage also achieved significance (HR=2.8; p=0.03). Results ...