Gudbrandsdottir G, Aarstad HH, Hjelle KM, et al. - Among patients with renal cell carcinoma (RCC), serum samples taken across treatment were assessed for levels of IL-1/IL-6 family cytokines and relevant receptors. In addition, the possible interactions were examined between these measurements, immunohistochemistry and intratumoral blood flow. A total of 40 patients undergoing open surgery for renal tumors were included. Findings revealed an increase in serum levels of IL-6 during surgery. Relative to the periphery, the renal vein showed higher intraoperative IL-6 and s-IL-33R values, suggesting secretion from the tumor or tumor microenvironment itself. In support of this, they noted an almost general expression of IL-6/s-IL-6R in tumor cells and IL-6 in vasculature in the tumor microenvironment. Remarkable stability was observed in other studied cytokines/receptors across all measurements.