Immunohistochemical evidence of urokinase-type plasminogen activator in primary and metastatic tumors of pulmonary adenocarcinoma.

The urokinase-type plasminogen activator (u-PA) was used to study 96 cases of lung adenocarcinoma and 49 cases of lymph node metastatic adenocarcinoma. We made use of the immunohistochemistry of paraffinized samples. u-PA was detected in the cytoplasm of tumor cells, and the number of positive cells was higher in patients with T2 or T3 than in those with T1 disease (P less than 0.01). These u-PA-positive tumor cells were more frequent in patients with N2 than in those with N1 disease (P less than 0.01). Such cells were also detected in patients with N1 rather than N0 disease (P less than 0.01). When we compared the frequency of u-PA-positive tumor cells in metastatic lesions with that in primary ones, the former tended to be higher. On the other hand, the frequency of u-PA-positive cells in primary tumors of patients with a recurrence was higher than in those with no recurrence. Thus, u-PA is an important prognostic indicator associated with tumor growth and lymph node spread. If u-PA is detected in a tumor, a recurrence can be expected.