Purpose: A strong prognostic impact of urokinase-type plasminogen activator (uPA) and its inhibitor and plasminogen activator inhibitor type 1 (PAI-1) as individual factors is well established in breast cancer. The improvement in clinical risk assessment gained by combining these factors is evaluated here.
Patients and methods: uPA and PAI-1 levels were prospectively measured by enzyme-linked immunosorbent assay in tumor tissue extracts of 761 patients with primary breast cancer.
Results: In the clinically important subgroup of node-negative patients without adjuvant systemic therapy (n = 269; median follow-up, 60 months), the clinical value of testing both uPA and PAI-1 is demonstrated. The criterion either or both high identifies with high sensitivity the patients at high relapse risk while keeping more than half in the low-risk group. uPA/PAI-1 is the strongest predictor of disease-free survival and overall survival; patients with high uPA/PAI-1 have an increased relapse risk (P <.001; relative risk, 4.8; 95% confidence interval [CI], 2.5 to 9.1), in particular for early relapse. Even within risk groups stratified by established criteria (nodal or menopausal status, tumor size, grade, or steroid hormone receptors), uPA/PAI-1 provides significant risk group discrimination. In the whole collective, the significant interaction between uPA/PAI-1 and adjuvant systemic therapy suggests a benefit from adjuvant therapy in high-risk patients as defined by uPA/PAI-1.
Conclusion: The clinical relevance of the two tumor-invasion factors uPA and PAI-1 is greatest when they are used in combination. The particular combination of uPA and PAI-1 (both low v either or both high) is superior to either factor alone and supports risk-adapted individualized therapy decisions.