Response to neoadjuvant chemotherapy and survival in micropapillary urothelial carcinoma: data from a tertiary referral center and Surveillance, Epidemiology, and End Results (SEER) program

Abstract Introduction Micropapillary carcinoma (MPC) is a rare urothelial carcinoma (UC) variant with conflicting data guiding clinical practice. In this study, we explored oncologic outcomes in relation to neoadjuvant chemotherapy (NAC) in a retrospective cohort of patients with MPC, alongside data from SEER-Medicare. Materials and Methods We retrospectively identified patients with MPC or conventional UC (CUC) without any variant histology, undergoing radical cystectomy (RC) in our institution (2003-2018). SEER-Medicare was also queried to identify patients diagnosed with MPC (2004-2015). Clinicopathologic data and treatment modalities were extracted. Overall survival (OS) was estimated with the Kaplan-Meier method. Mann-Whitney-Wilcoxon and chi-squared tests were used for comparative analysis and Cox regression for identifying clinical covariates associated with OS. Results Our institutional database yielded 46 patients with MPC and 457 with CUC. In SEER-Medicare, 183 patients with MPC were identified and 63 (34%) underwent RC. In the institutional cohort, patients with MPC had significantly higher incidence of cN+ (17% vs. 8%), pN+ stage (30% vs 17%), carcinoma-in-situ (CIS, 43% vs 25%) and lymphovascular invasion (LVI, 30% vs 16%) at RC vs. those with CUC (all p Conclusion Pathologic response to NAC was not significantly different between MPC and CUC, while MPC histology was not an independent predictor of OS. Further studies are needed to better understand biological mechanisms behind its aggressive features as well as the role of NAC in this histology variant.