Adjuvant chemotherapy is ineffective in patients with bladder cancer and variant histology treated with radical cystectomy with curative intent

Objectives Adjuvant chemotherapy (ACT) is recommended for non-organ-confined bladder cancer (BCa) after radical cystectomy (RC) and pelvic lymph node dissection (PLND), but there are sparse data regarding its specific efficacy in patients with histological variants. The aim of our study was to evaluate the role of ACT on survival outcomes in patients with variant histology in a large multicenter cohort. Materials and methods We retrospectively evaluated data of 3963 patients with BCa treated with RC and bilateral PLND with curative intent at several institutions between 1999 and 2018. The histological type was classified into six groups: pure urothelial carcinoma (PUC) or squamous, sarcomatoid, micropapillary, glandular and neuroendocrine differentiation. Multivariable competing risk analysis was applied to assess the role of ACT on recurrence and cancer-specific mortality (CSM) in each histological subtype. Results Of the 3963 patients included in the study, 23% had variant histology at RC specimen and 723 (18%) patients received ACT. ACT was found to be significantly associated with reduced risk of recurrence (sub-hazard ratio [SHR]: 0.55, confidence interval [CI] 0.42-0.71,p < 0.001) and CSM (SHR: 0.58, CI 0.44-0.78,p < 0.001) in the PUC only, while no histological subtype received a significant benefit on survival outcomes (allp > 0.05) from administration of ACT. The limitation of the study includes the retrospective design, the lack of a central pathology review and the number of ACT cycles. Conclusion In our study, the administration of ACT was associated with improved survival outcomes in PUC only. No histological subtype found a benefit in overall recurrence and CSM from ACT.