Dissemination Risk Index Based on Plasminogen Activator System Components in Primary Breast Cancer

Abstract

PURPOSE: To study interactions between disease-free survival (DFS) and four components of the plasminogen activator system: urokinase-type plasminogen activator (uPA), its two inhibitors (PAI-1 and PAI-2), and its membrane receptor uPAR. PATIENTS AND METHODS: We conducted a retrospective study of 499 primary breast cancer patients (median follow-up, 6 years). uPA, PAI-1, and PAI-2 were determined on cytosols and uPAR on solubilized pellets, using enzyme-linked immunoadsorbent assay kits (American Diagnostica, Greenwich, CT). Classical univariate and multivariate statistical methods were used together with multiple correspondence analysis to graphically examine interactions between the variables and outcome. RESULTS: By univariate analysis, higher uPA and PAI-1 values were significantly related to shorter DFS (P = .002; P < .00002). PAI-2 was not significantly related to DFS, although patients with high and very low PAI-2 values had a longer DFS. Multiple correspondence analysis showed the parallel impact of uPA and PAI-1 on outcome, and the clearly different behavior of PAI-2 compared with PAI-1. The prognostic contribution of uPAR seemed weak by both methods. A dissemination risk index [uPA × PAI-1/(PAI-2 + 1)], taking into account the modulation of uPA proteolytic activity by the ratio of its two inhibitors, was then tested. Dissemination risk index was selected as an independent variable in the Cox model in the overall population (P < .000001) and in node-positive patients (P < .00001). It was the only variable selected in node-negative patients (P = .003). CONCLUSION: A dissemination risk index determined on primary tumor and taking into account the different effects of PAI-1 and PAI-2 on uPA can be of major help in clinical management of breast cancer, particularly in node-negative patients.