The impact of pathologic downstaging with neoadjuvant chemotherapy on survival of patients with muscle-invasive bladder cancer.

491Background: Achieving a pathologic complete response (pCR) with neoadjuvat chemotherapy (NAC) in patients with muscle-invasive bladder cancer (MIBC) has been correlated with improved survival. Such findings have served as justification for using pCR as an intermediate endpoint for clinical trials and perpetuated the notion that NAC only benefits patients achieving a pCR. The impact of downstaging (pDS) on outcomes of patients with MIBC treated with NAC has been underexplored. Methods: The National Cancer Database (NCDB) was queried to identify patients with MIBC (cT2-4N0M) treated with platinum-based NAC. A multivariable Cox model including either pDS or pCR and adjusted for potential confounders was generated and c-indices were computed to evaluate whether the inclusion of pDS or pCR was more informative in predicting overall survival (OS). Results: Overall 2,010 patients from NCDB met inclusion criteria. The median follow-up for survivors was 36 months with a 5-year OS of 47% (95% CI 44, 50%). Overal...