Association Between Surgical Volume and Survival Among Patients With Variant Histologies of Bladder Cancer

Objective To examine the relationship between hospital volume and the management of bladder cancer variant histology. Variant histologies of bladder cancer are rare which limits the ability for providers to develop expertise however there is a clear hospital and/or surgeon-volume relationship for management of rare or complex surgical and/or medical diseases. Methods We queried the National Cancer Database from 2004-2016 for all cases of bladder cancer, identifying cases of variant histology. Our primary outcome was overall survival while secondary outcomes included identifying treatment patterns. Hospitals were stratified into those that managed ≤2, >2-4, >4-6, and ≥6 cases per year of variant histology. Results We identified 23,284 patients with bladder cancer of variant histology who were treated at 1301 hospitals. Few institutions had high volume experience with this disease: 18.5% (n = 241) treated >2 patients annually and 5.7% (n = 76) treated >4 cases annually. Hospital volume positively correlated with utilization of early radical cystectomy (RC) in non–muscle invasive disease and neoadjuvant chemotherapy in muscle-invasive disease. On multivariable analysis, increased hospital volume was associated with improved survival. After stratifying by sub-type, hospital volume continued to be associated with improved survival for squamous, small cell, and sarcomatoid cancers. Conclusion Management of variant histology urothelial carcinoma at high-volume centers is associated with improved overall survival. The mechanisms of this are multifactorial, and future research should focus on improvement opportunities for low-volume hospitals, centralization of care, and/or increased access to care at high-volume centers.