This article examines the prognostic importance of urinase type
plasminogen activators (uPA) and of
plasminogen activator inhibitors (PAI-1) in cases of primary
oral squamous cell carcinoma. Tissue samples were taken from the core of the tumour in 58 such primary surgical patients. The levels of uPA and
PAI-1 were determined using ELISA. Statistical significance was calculated using the chi2- and log-rank tests. The mean follow-up (n=58) was 23 months. In order to determine prognostic value, the time before relapse was used. The mean time before relapse was 19 months. A total of 28 (40%) patients relapsed (local n=13, lymph node n=3, local and lymph node n=1, lymph node and skin n=1, other locations n=5). Such patients had significantly raised uPA (P<0.012) and
PAI-1 (P<0.014) levels in the primary tumour. A optimal cutoff value for uPA (4.58 ng/mg) and
PAI-1 (106.3 ng/mg) was determined using the multiple log-rank test. There was no significant correlation for patients with low or high levels (i.e. lower or higher than the cutoff value, respectively) with the usual clinical parameters such as localisation, N-stage, T-stage, differentiation and
residual tumor status. Older patients (>58 years) had significantly higher levels of uPA and
PAI-1 (P<0.017 and P<0.02, respectively). The likelihood of relapse was significantly higher in patients with high levels (uPA P<0.009, PAI-1 P<0.008). If the patients were divided into three groups depending on uPA and
PAI-1 levels (group 1: uPA and PAI-1 low, n=35; group 2: uPA or PAI-1 high, n=12; group 3: uPA and PAI-1 high, n=11), relapses were more common in group 3 than in groups 1 or 2 (P<0.023). Patients with only surgical
therapy (n=29) and those with postoperative
radiotherapy (n=29) were used to evaluate postoperative follow-up. Cutoff levels were calculated for both groups. In the surgical therapy group this was uPA=5.63 ng/mg and PAI-1=106.3 ng/ml and in the surgical
therapy plus
radiotherapy group uPA=4.13 ng/mg and PAI-1=97.02 ng/mg. Kaplan-Meier curves showed a marked tendency for patients with higher levels to relapse more often. This is significant for surgical patients for
PAI-1 (P<0.01) and for
radiotherapy patients for uPA (P<0.04)