Fig. 2

Cancer-specific survival (CSS) of clear cell renal cell carcinoma (ccRCC) tumors of our validation cohort predicted by the simplified RT-PCR-based S3₁₅-score. Kaplan–Meier curves showing CSS of (a) the extended ccRCC cohort 2 (n = 108) and (b) the non-metastatic (n = 92) and metastatic subsets (n = 15) of this cohort. Groups are defined by the cut-off of the S3₁₅-score, as determined by conditional inference tree models. c S3₁₅-score significantly improves the established SSIGN prediction score. χ² statistic values depict the improvement of the model likelihood when risk classification based on the S3₁₅-score (red) was added to the Cox model initially including only the SSIGN score (blue; left) or vice versa (right). χ² test P values are shown in the bars. HR hazard ratio, CI confidence interval. Detailed information on statistical methods is provided in Additional file 1: Supplementary methods