The course of fibrinolytic proteins in children with malignant bone tumours

To evaluate the role of fibrinolytic and proteolytic proteins in children a nd adolescents suffering from Ewing sarcoma or osteosarcoma with respect to postoperative complications and late outcome, a prospective two-arm two-ce ntre study was conducted. Plasminogen, plasminogen activator inhibitor (PAI )-1, tissue-type plasminogen activator (t-PA) and urokinase plasminogen act ivator (u-PA) were investigated in the pre-surgical period and in the posto perative follow-up period in children suffering from Ewing sarcoma (ES; n = 36) or osteosarcoma (OS; n = 39). In addition, the factor V mutation (FV) Q(506), protein C, protein S, antithrombin and lipoprotein (a) were determi ned. All children received LMWH (Enoxaparin(R)) 1 mg/kg sc. once daily over a period of 6 weeks to 3 months. Besides a short-lasting increase of PAI-1 in patients with OS on day 1 and in children with Es on day 14, a small an d significant but clinically irrelevant difference was found on days 7-10 f or plasminogen, t-PA and u-PA. No thromboembolic complications occurred in patients treated with LMWH and having a prothrombotic genetic risk factor. Within one year of surgery 7 out of 36 patients with ES and 5 out of 39 chi ldren with OS showed a relapse of their disease. Prior to the first local t umour therapy, 5 out of 7 children with ES and relapse had elevated u-PA co ncentrations compared with 2 out of 5 children in the OS group. No such dif ferences were found for PAI-1- or t-PA antigen. Conclusion The role of u-PA as a possible follow-up marker for a poorer out come in children with ES should be evaluated in a prospective multicentre s tudy.