CCR4 and renal cell carcinoma: Previous studies have shown a significant correlation between chemokine receptor status in human cancers and prognosis and/or metastases in a variety of malignant tumors such as T-cell leukemia (CCR4), hepatocellular carcinoma (CCR6), gastric carcinoma (CCR7), renal cell carcinoma (CXCR3), ovarian cancer (CXCR4), osteosarcoma (CXCR4), colorectal cancer (CCR7 and CXCR4), and malignant melanoma (CXCR3 and CXCR4) [22].