Cytokine levels in cystic renal masses associated with renal cell carcinoma

Purpose: We compared cytokine levels in fluid from renal cysts with and without renal cell carcinoma. Materials and Methods: Fluid was aspirated from 18 renal cysts without (benign) and 21 with renal cell carcinoma (malignant). Serum from patients with renal cell carcinoma and healthy controls was collected and cytokines were measured by enzyme-linked immunosorbent assay. Results: Interleukin-6 (IL-6) and basic fibroblast growth factor concentrations were higher in malignant than benign cysts or serum (p < 0.006). Epidermal growth factor levels were significantly higher in malignant cysts and serum than in benign cysts (p < 0.01). IL-6 levels in malignant cysts positively correlated with the erythrocyte sedimentation rate (R = 0.80) and C-reactive protein (R = 0.86), and they were higher in grade 3 than in grade 2 tumors. Basic fibroblast growth factor levels were significantly higher in malignant cysts associated with hypervascular than hypovascular tumors (p = 0.029). Conclusions: Cytokine levels in aspirated fluid may help to identify malignant renal cysts and indicate the characteristics of coexisting tumors.