Adjuvant Chemotherapy and Survival After Radical Cystectomy in Histologic Subtype Bladder Cancer

We used the National Cancer Database to identify patterns of adjuvant chemotherapy use and survival outcomes in patients with non -metastatic histologic subtype bladder cancer and adverse pathologic features at the time of radical cystectomy. AC was associated with significantly longer overall survival in patients and for squamous, sarcomatoid, and micropapillary cohorts after stratified by subtype. Objectives: Patients with histologic subtype bladder cancer (HSBC) suffer worse outcomes than those with conventional urothelial carcinoma (UC). We sought to characterize the use of adjuvant chemotherapy (AC) in HSBC after radical cystectomy (RC) using the National Cancer Database (NCDB). Materials and Methods: We retrospectively queried the NCDB (2006-2019) for patients with non -metastatic bladder cancer (BC) who underwent RC ( N = 45,797). Patients were stratified by histologic subtype and receipt of AC. Multivariable logistic regression determined associations of demographic and clinicopathologic features with receipt of AC. Multivariable Cox regression evaluated associations between receipt of any AC and overall survival (OS). Results: We identified 4,469 patients with HSBC classified as squamous, adenocarcinoma, small cell, sarcomatoid, micropapillary, or plasmacytoid. Squamous comprised 31% of the HSBC cohort, followed by small cells and micropapillary. Black patients were presented with a higher prevalence of adenocarcinoma (119/322, 37.0%). Use of AC was highest in plasmacytoid and small cell (30% each) and lowest in squamous (11%). Neuroendocrine histology was independently associated with greater odds of receiving AC (HR 1.6, 95% CI 1.37-1.87), while squamous cell histology was associated with lower odds (HR 0.61, 95% CI 0.53-0.71). On multivariable Cox regression analysis, treatment with AC was associated with significantly longer OS (HR 0.69, 95% CI 0.59-0.81) and for squamous, sarcomatoid, and micropapillary cohorts after stratified by subtype. Conclusions: AC was variably used among patients with HSBC and was associated with OS benefit in such patients.