We performed immunohistochemical staining of CASZ1 in 896 ccRCC cases and demonstrated that a low expression of CASZ1 was associated significantly with advanced clinicopathologic parameters of ccRCC such as large tumor size, high WHO/ISUP grade, high T category and M category, and high TNM staging. This evidence concerns the gene CASZ1 and nonpapillary renal cell carcinoma.