ABSTRACT
BACKGROUND: The impact of variant histologies on overall survival (OS), as well as their influence on the response to neoadjuvant and adjuvant chemotherapy (AC) is well studied in patients diagnosed with bladder cancer. However, little is known about tumors with variant histologies of the upper urinary tract. The objective of this study was to assess the survival of the predominant variant histologies of tumors of the renal pelvis (RPT) after surgical intervention, and to examine the influence of AC on the OS of the different variant histologies. METHODS: We identified 21,318 patients with RPT undergoing surgical intervention using the National Cancer Database for the period 2004-2015. We employed multivariable Cox proportional hazards regression models and Kaplan-Meier curves to evaluate the OS according to variant histology. Separate multivariable Cox regression models were used to assess the specific effect of AC on OS of the histological subgroups. RESULTS: The majority of patients were diagnosed with pure urothelial carcinoma (PUC) (96.1%). Overall, 826 patients were diagnosed with variant histologies (adenocarcinoma N = 298, squamous cell carcinoma N = 291, sarcomatoid N = 137, others N = 100). Compared to PUC, adenocarcinomas showed longer OS (HR 0.76, 95% confidence interval (CI) 0.62-0.94, p = 0.01), while sarcomatoid tumors had shorter OS (HR 1.59, 95% CI 1.12-2.26, p = 0.011). A subgroup analysis of patients undergoing AC showed a survival benefit in patients with PUC (HR 0.81, 95% CI 0.73-0.9, p < 0.001). CONCLUSION: We found that variant histologies of upper urinary tract carcinomas exhibit different survival rates and that AC was only associated with an OS benefit in patients with PUC.