In this cut-off value, IL13Rα2-positivity was significantly associated with tumor size (P = 0.004), tumor stage (P = 0.002), histologic nuclear grade of tumor cells (P < 0.001), and histologic subtype of RCC (P = 0.005) in 229 cases of RCCs (Table 1). This evidence concerns the gene IL13RA2 and renal cell carcinoma.