KL and nonpapillary renal cell carcinoma: Recently, it has been reported that the kidney is the major source of circulating αKlotho in the systemic circulation, and is responsible for its clearance.4 On these premises, we evaluated, for the first time, the prognostic role of the soluble form of Klotho in sera of a large cohort of patients who underwent radical or partial nephrectomy for ccRCC.