In previous studies, certain biomarkers of ccRCC were identified, such as urinary RKIP/p-RKIP, kynurenine-to-tryptophan ratio (KTR), glucose-6-phosphate isomerase (GPI)/autocrine motility factor (AMF), αKlotho, CA 15–3, CA 125, and β-2 micro-globulin, and a few metabolomics-based biomarkers have been reported to be associated with ccRCC prognosis [20,21,22,23,24,25,26,27]. Here, GPI is linked to nonpapillary renal cell carcinoma.