TDO2 and nonpapillary renal cell carcinoma: After Univariate Cox regression, 31 genes including AANAT, ASMT, CBS, CBSL, CKM, CSAD, HAO1, IL4L1, NNMT, PSAT1, PSMB10, PYCR1, RPL13, RPL18, RPL22L1, RPL27A, RPL28, RPL35, RPL36, RPL36A, RPL37, RPLP0, RPS19, RPS2, RPS20, RPS8, SLC45A2, SLC5A5, SLC6A7, TDO2, and UROC1 demonstrated worse prognosis, while the other 26 genes were correlated with better outcomes in ccRCC patients (Figure 2E).