CXCL8 and neoplasm: In addition to their roles in the angiogenesis process, these four proteins were selected for the present study on the basis of the results of prior correlative biomarker studies in RCC, suggesting prognostic value for circulating VEGF-A [21, 22], possible predictive or prognostic value for circulating VEGF-C and sVEGFR-3 in patients treated with sunitinib [23] and an association between elevated tumor IL-8 messenger ribonucleic acid (mRNA) expression and advanced disease [24].