CA9 and renal cell carcinoma: Therefore, there is a crucial need to identify specific molecular biomarkers at the time of nephrectomy serving to predict a potential RCC progression.24 A prognostic role has been proposed for several circulating biomarkers associated with different features of RCC biology, including carbonic anhydrase IX (CAIX), hypoxia-inducible factor-1α (HIF1α), CA15-3, and some cancer metabolism-related proteins.25–28