Hospital Volume Threshold for the Treatment of Retroperitoneal Sarcoma.

ABSTRACT

BACKGROUND: Retroperitoneal sarcomas (RPS) are rare, histologically heterogeneous, and anatomically complex tumors. National Comprehensive Cancer Network guidelines recommend evaluation and management by multidisciplinary teams with experience in sarcoma. Our aim was to determine an appropriate hospital volume threshold for the treatment of RPS. PATIENTS AND METHODS: Patients undergoing resection of RPS were identified from the National Cancer Data Base (1998-2012). Multivariable modeling with restricted cubic splines was employed to examine the association between hospital volume and survival and identify possible hospital volume threshold. RESULTS: The study included 5,340 patients who underwent surgery at 909 different hospitals. Median annual volume was two cases per year. After adjustment, hospital volume was associated with improved survival (p=0.01), without cutoff. The cohort was then grouped into Low-volume (≤5 cases/year), intermediate-volume (6-10 cases/year), and high-volume (>10 cases/year). The majority of patients were treated in low-volume hospitals (86%), compared to 9% in intermediate- and 5% in high-volume centers; 44% of patients were treated in hospitals that performed one case per year. Compared to low-volume, high-volume hospitals more often had patients with high-grade and larger tumors. Adjusted 90-day mortality was significantly lower in high- vs. low-volume hospitals (odds ratio(OR)=0.25, p=0.02). With adjustment, treatment in high- vs. low-volume hospitals was associated with lower odds of margin positivity (OR=0.58, p=0.001), and improved overall survival (hazard ratio(HR)=0.61, p=0.002). CONCLUSION: Treatment of RPS in high-volume centers is associated with significant reduction in short-term mortality and improved long-term survival. Hospital volume may be a surrogate for the infrastructure and support necessary for the optimal management of these complex malignancies.