Summary Urokinase-type plasminogen activator (uPA) is a potentially important prognostic factor in breast cancer for identifying patients at high risk of recurrence. This retrospective study assessed two enzyme-linked immunosorbent assay (ELISA) methods measuring uPA antigen levels in 499 primary breast cancer cytosols. Both uPA methods were applied to cytosols used routinely for oestrogen (ER) and progesterone (PgR) receptor assays. uPA was determined using a classical ELISA method (Imubind; American Diagnostica) and a novel automatic immunoluminometric assay (Lia; Sangtec Medical). The uPA Imubind method revealed about twice as much uPA antigen (median 0.75 ng mg-1 protein) as the uPA Lia method (median 0.38 ng mg-1 protein). The correlation coefficient between the two methods was acceptable (r = 0.81), but the two techniques are not interchangeable. Univariate analyses confirmed the poor outcome of patients whose tumours contained large amounts of uPA, regardless of the technique used. Multivariate analyses showed that uPA Imubind and uPA Lia values were both strong independent prognostic factors.Keywords: urokinase plasminogen activator; luminometric immunoassay; prognosis; breast cancer Evidence has accumulated that invasion and metastasis by solid tumours require the action of tumour-associated proteases, which promote the dissolution of the surrounding tumour matrix and basement membranes. In several independent studies of a variety of cancer types, i.e. breast (Dano et al, 1985;Duffy et al, 1988), colorectal (Ganesh et al, 1994;Skelly et al, 1995), lung (Oka et al, 1991), ovary (Kuhn et al, 1994), gastric (Nekarda et al, 1994;Cho et al, 1997) and bladder cancer (Hasui et al, 1992), high levels of the serine protease urokinase-type plasminogen activator (uPA) antigen in tumour extracts were associated with rapid disease progression and poor prognosis. In this study of 499 primary breast cancer tumours, we used two different assay methods for uPA antigen, in order to compare an enzyme-linked immunoassay (uPA Imubind; American Diagnostica) with a new automatic immunoluminometric assay (uPA Lia; Sangtec Medical), to assess the relationships between uPA values and clinical and histological factors and to evaluate the prognostic value of the two methods in multivariate analyses.
MATERIALS AND METHODS PatientsThe study group consisted of 499 breast cancer patients treated at the Centre Rene Huguenin (CRH) between 1981 and 1989. The median age was 58 years (range 24-84 years). Patients were selected according to the following criteria: (1) primary, unilateral breast tumour; (2) full follow-up at CRH; (3) previously untreated, Correspondence to: C Bouchet without evidence of metastatic disease or any other malignant tumour at the time of diagnosis; (4) surgery as the first treatment; and (5) complete clinical, histological and biological information, especially concerning hormone receptors and antigen levels of uPA measured in cytosols by the two methods. All tumours were graded by a method based on the criteri...