In renal cell carcinoma, CHAC1 functions as a stage-stratified biomarker, where reduced expression in early-stage ccRCC portends unfavorable clinical outcomes, while overexpression in advanced disease signifies aggressive phenotypes, as quantitatively validated by the FPTOS_score prognostic model (HR = 2.028, 95% CI: 1.640-2.507). Here, CHAC1 is linked to nonpapillary renal cell carcinoma.