Increased tissue factor expression is an independent predictor of mortality in clear cell carcinoma of the kidney.

PURPOSE Increased expression of tissue factor (TF), a primary initiator of the extrinsic coagulation pathway, has been associated with a worse prognosis in a variety of solid tumors. We report for the first time the correlation of the immunohistochemical expression of tissue factor with clinical and pathological outcomes in clear cell carcinomas of the kidney. MATERIALS AND METHODS immunohistochemical expression of tissue factor was evaluated in 58 paraffin-embedded samples of clear cell carcinomas of the kidney treated at the same university hospital, that was correlated with clinical and pathological variables and with overall survival. RESULTS high intensity tissue factor expression (TF area > 10 µ m2) was observed in 22.4% of the tumors (13 patients), and was an important predictor of overall mortality, both in univariate and multivariate analysis (p < 0.05). Median overall survival for both groups was 66 months; 78.2 months for patients in the group of lower TF expression and 27.5 months for patients in the group of higher TF expression (log rank p < 0.001). The hazard ratio for mortality was 9.7 (CI 3.7-25.6) for tumors with increased TF expression. CONCLUSIONS Increased immunohistochemical expression of TF was an important independent predictor of mortality in a contemporary cohort of patients with clear cell carcinoma of the kidney. Further studies are necessary to define the role of TF in clinical practice.