Plasma levels of cellular fibronectin in patients with localized and metastatic renal cell carcinoma.

Clinical markers for renal cell carcinoma (RCC) are lacking. Fibronectin is a glycoprotein that plays an important role in cellular attachment and cell spread. The aim of this study was to test the clinical suitability of cellular fibronectin (cFN) in plasma as a tumor marker for RCC and to determine a possible relationship between cFN plasma levels and stage of disease. Therefore, cFN was determined in the plasma of patients with localized (n = 40) and metastatic (n = 20) RCC using a time-resolved fluorescence immunoassay. Fifty patients with different non-malignant urological disorders were recruited as a control group. In the control group, mean cFN plasma levels amounted to 553 ng/ml. In patients with localized RCC, plasma concentrations of cFN were increased (1,295 ng/ml; p < 0.01). Patients with metastatic disease had the highest concentrations (3,842 ng/ml). Statistical analysis demonstrated a significant difference between controls, and patients with localized and metastatic RCC (p < 0.01), with a sensitivity of 80%, a specificity of 78% and a positive predictive value of 81% using a cutoff value of 540 ng/ml (receiver-operating characteristic curve analysis). These data suggest that cFN is not a realistic marker for the detection of RCC. However, elevated plasma levels in more advanced disease and an acceptable predictive value could indicate that cFN is useful as a follow-up tool in the management of RCC patients.