CXCL8 and nonpapillary renal cell carcinoma: However, nccRCC was specifically investigated in only one study27 and was mixed with sarcomatoid ccRCC, translocation RCC, and unclassified RCC in another28; thus, the issue of a differential impact of high circulating IL-8 levels in nccRCC cannot be solidly addressed and remains a potential limitation of this meta-analysis, also considering the high degree heterogeneity of distinct histological subtypes included in the nccRCC subgroup.