CA9 and nonpapillary renal cell carcinoma: Some studies found different or even opposite effects on different subtypes [19, 44, 95], for instance, a study reported that in ccRCC, high CAIX expression had more favorable prognosis in OS and RFS, while in papillary RCC (pRCC) the result was opposite, although the P value did not reach the level of statistical significance in OS (P = 0.1645 for ccRCC, P = 0.3861 for pRCC).