Urokinase-type plasminogen activator: a potent marker of metastatic potential in human cancers.

Urokinase-type plasminogen activator (uPA) is a serine protease that is causally involved in cancer progression, especially invasion and metastasis. Multiple studies have shown that breast cancer patients whose primary cancer contains high levels of uPA have a significantly worse outcome than patients with low levels. As a prognostic marker for breast cancer the information supplied by uPA is both independent of traditionally used factors and significant in the important subgroup of axillary-node patients. Paradoxically, high levels of plasminogen activator inhibitor-1 (PAI-1), an endogenous inhibitor of uPA, also predict for aggressive disease. Recently, the prognostic impact of both uPA and PAI-1 in axillary node-negative breast cancer was confirmed using two different Level 1 Evidence studies, i.e. in both a randomized prospective trial and a pooled analysis. Therefore, uPA and PAI-1 appear to have fulfilled all the criteria for the routine assessment of prognosis in newly diagnosed breast cancer patients.