Clinical predictors of sarcomatoid kidney cancer: The results of a UCLA and french UroCCR network collaboration

598 Background: Predisposing factors for sarcomatoid dedifferentiation of renal cell carcinoma (sRCC) remain unknown. We highlighted the association of potential contributing medical conditions with the presence of sRCC. Methods: Patients with a renal cell carcinoma (RCC) from UCLA and the French UroCCR-45 study (only sRCC) were included in the study. Characteristics of patients with sRCC were compared with patients with RCC without sarcomatoid features (nsRCC) in univariable and multivariable logistic regression analyses. We quantified the association of age, gender, smoking status, hypertension, kidney function, and endocrine disorders: diabetes and hypothyroidism with sRCC. Results: A total of 2764 were included in the study (586 sRCC vs. 2178 nsRCC). On univariable analysis, age (OR=1.02, 95%CI [1.01-1.03], p