O2212 STAGE IIB KNEE OSTEOSARCOMAS. A STUDY OF MMP-9 IN SURVIVING TUMOUR CELLS

Abstract

Aims: The purpose of this study is to investigate whether the expression of MMP-9 (matrix metalloproteinase-9) is a potentially useful marker in osteosarcomas. Methods: 55 patients with stage IIB knee osteosarcomas were treated in our unit and had a median follow-up of 68 months. In addition to clinical data, MMP-1, MMP,-2, MMP-3, MMP-7, MMP-9 and MMP-13 were studied in the resection specimens, using immunohistochemical methods. The importance of all factors was studied using the log-rank test, and the overall survival of patients was calculated using Kaplan-Meier survival curves. Multiple variable analysis was carried out using Cox regression models with variables chosen forward and backward stepwise methods with deviance statistics. Signiþcance was set at p< 0.05. Results: On multiple variable analysis only the MMP-9 status of the tumour cells had a signiþcant effect on overall (p=0.032) and disease free survival (p=0.014). Conclusions: Our study shows that some post-chemotherapy osteosarcoma specimens express MMP-9 in the surviving tumour cells after chemotherapy. We believe that MMP-9 in the osteosarcoma cells which survive chemotherapy, contributes to recurrence because of the ability of these cells, to stimulate a new vascular network. The relationship between osteosarcomas and MMP-9 is worthy of further study.