Examination of genomic copy number alterations in renal cell carcinoma with sarcomatoid features.

478 Background: Sarcomatoid differentiation is an uncommon histological finding in renal cell carcinoma (RCC) that may develop from any RCC subtype and is associated with a very poor prognosis. The identification of genetic alterations that drive this aggressive phenotype could aid in the development of more effective targeted therapies. In this study, we aimed to identify unique copy number alterations (CNAs) in patients with sarcomatoid RCC when compared to those with other RCC subtypes. Methods: Genomic copy number analysis was performed using single nucleotide polymorphism (SNP)-based microarrays on tissue extracted from the tumors of 80 patients (9 with sarcomatoid features (sRCC), 39 clear cell (ccRCC), 26 papillary (pRCC) and 6 chromophobe RCC (chRCC)) who underwent renal mass excision between 2010 - 2014. Statistical analysis was performed using Kaplan Meier (KM) survival analysis, t-tests and Fisher exact tests where appropriate. Results: sRCC tumors exhibited significantly higher numbers of CNAs...