Robustness of the 16-gene signature for prediction of recurrence-free interval in localized clear cell renal cell carcinoma.

455 Background: The Renal Cancer assay is a clinically validated RT-PCR assay developed to estimate the risk of recurrence in stage I-III clear cell renal cell carcinoma (ccRCC) patients (pts) treated with nephrectomy. The assay measures expression of 16 genes that are combined to calculate the Recurrence Score result (RS). The RS is associated with recurrence, renal cancer-specific survival and overall survival (all p<0.001) (Escudier, ASCO 2014). The performance of the RS in clinically relevant subgroups, compared to the Leibovich score, and its within-patient variability was examined. Methods: The algorithm, endpoints, methods, and analysis plan were pre-specified prior to merging clinical and molecular data. RT-PCR of RNA from fixed paraffin-embedded ccRCC tissue was performed without knowledge of clinical data. Recurrence-free internval (RFI) was analyzed using Cox regression stratified by stage with data censored at 5 years, and Kaplan-Meier methods. Multivariable models incorporating the Leibovich ...