Renal Sarcoma: A Population-Based Study.

Introduction: Renal sarcomas are exceedingly rare and lack a prognostic stage classification. We thus aimed to investigate the contemporary clinicopathologic characteristics and outcomes of renal sarcomas at a national level.

Patients And Methods: We utilized the Surveillance, Epidemiology, and End Results database to extract data on patients with renal sarcoma diagnosed between 2004 and 2015. We estimated median, 1-, 3-, and 5-year overall survival (OS) probabilities via Kaplan-Meier curves and used multivariable regression to compare OS between different patient groups.

Results: We identified 365 patients; at diagnosis, 104 patients (28.5%) had stage I disease (T1N0M0), 133 patients (36.4%) patients had stage II disease (T2-4N0M0), and 117 patients (32.1%) patients had stage III disease (any T, N1, or M1). Median survival was 105 months (interquartile range [IQR], 29 - not reached) for stage I disease, 46 months (IQR 14-118 months) for stage II disease, 8 months (IQR 3-28 months) for stage III disease, and 32 months (IQR, 8-116 months) for the entire cohort. Patient age (hazard ratio [HR] for death [per year] 1.02, 95% confidence interval [95% CI] 1.00-1.04), stage (II vs. I: HR 1.71, 95% CI 1.00-2.92; III vs. I: HR 4.93, 95% CI 2.68-9.05), grade (grade 3 vs. grade 1: 3.07, 95% CI 1.18-8.00; grade 4 vs. grade 1: HR 3.66, 95% CI 1.41-9.49), and possessing medical insurance (HR 0.40, 95% CI 0.16-0.94) were independently and significantly associated with OS. Performance of nephrectomy also trended towards independently improving OS (HR 0.23, 95% CI 0.05-1.09).

Conclusion: A novel staging classification for renal sarcomas into a 3-stage system based on Tumor Node Metastasis (TNM) criteria produces distinct survival curves, although further studies are needed to robustly assess its validity.