gms | German Medical Science

Introduction: To date clinical markers for renal cell carcinoma (RCC) are not available. Fibronectin, a glycoprotein plays an important role in cellular attachment and promotion of migration. The aim of this study was to investigate the role of measuring 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.

Materials: cFN was determined in plasma of patients with localized (n=40, mean age 66y.) and metastatic (n=20, mean age 61y.) RCC by using a newly developed time-resolved fluorescence immunoassay. This sandwich-type assay, which is specific for the cellular form of FN, is based on a cFN-specific antibody (mouse, monoclonal) immobilized on standard enzyme-linked immunosorbent assay microwells. 50 patients (mean age 63y.) with various non malignant urological disorders were recruited as a control group.

Results: The control group showed median concentration cFN plasma levels of 430 ng/ml (181-1259 ng/ml). In comparison patients with localized RCC showed higher median concentrations of 784 ng/ml (384-5271ng/ml, p<0.01, Mann-Whitney U-test). Subdivided by pT-stage (p=0.061) and nuclear grading (p=0.468) no differences were detectable. Patients with metastatic disease showed the highest median concentrations of 1764 ng/ml (478-8887ng/ml). Statistical analysis calculated a significant difference between controls, localized and metastasized RCC (p<0.01, Kruskal-Wallis ANOVA). Using ROC-analysis between RCC patients and controls a cut-off value of 540 ng/ml for cFN in plasma was determined. Statistical analysis showed a sensitivity of 80 %, a specificity of 78 % and a positive predictive value of 81.4 %.

Conclusions: Our results suggest that cFN plasma levels can be a supporting tool for the diagnosis of localized and metastatic RCC. With higher plasma levels in metastatic disease and a good positive predictive value cFN may be helpful in monitoring patients after radical surgery for early detection of RCC recurrence or to monitor outcome of therapy in metastatic disease.