Abstract Abstract #2046 Background: Components of the plasminogen activator system play a key role in tumor invasion and metastasis. Tumor tissue levels of urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 showed a strong prognostic impact in node-negative and node-positive primary BC. uPA/PAI-1 were the first novel prognostic factors in primary BC reaching the highest level of evidence for their clinical utility and they have recently been recommended by ASCO for clinical decision making.
 Material and Methods: For the first time, correlations between uPA and PAI-1 concentrations in 73 primary tumor tissues and corresponding axillary lymphnodes (ALN) in node-negative (pN0) and node-positive (pN+) BC (1991-98) and their prognostic impact on disease-free (DFS) and overall survival (OS) were evaluated.
 Results: Median follow-up was 56 months. Overall, PAI-I (p=0,014) and uPA concentrations (p<0,001) were significantly higher in tumour tissue than in the corresponding ALN. There was no significant difference of PAI-1 in primary tumor tissue between pN0 and pN+ disease. In involved ALN (pN+), concentrations of PAI-1 but not of uPA, were significantly higher than in pN0 (p<0.001). Moreover, patients with higher PAI-1 concentrations in the corresponding ALN than in their primary tumor had a significantly shorter DFS (p<0,001) and OS (p=0.005).
 Discussion: Our clinical findings support the basic research data implicating uPA and PAI-1 as key proteolytic factors in metastasis-asociated processes such as adhesion, angiogenesis, invasion, proliferation and migration. For the first time, we are able to demonstrate that particularly PAI-1 seems to be involved in tumor metastasis in primary breast cancer with its concentrations being higher in involved ALN than in the primary tumor. Besides uPA/PAI-1 being validated and clinically useful prognostic factors, interference with the uPA/PAI-1 system thus promises to be an interesting therapeutic concept in BC. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2046.
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