Posters— Diagnostic Imaging/Pathology

MOLECULAR PREDICTORS OF OUTCOME IN PATIENTS WITH OSTEOSARCOMA

Reith JD, Casanova J, Berrey BH, Enneking WF, Scarborough MT (University of Florida, Gainesville, FL 32610)

Background: A variety of molecular markers related to survival, including bcl-2, p53, p-glycoprotein, CD95 (Fas), CD95-ligand (Fas-L), CD44, and CD44v, have been studied in a variety of human neoplasms, particularly carcinomas. Their significance in patients with osteosarcoma is largely unknown. The purpose of this archival study was to determine if there is a correlation between expression of these factors and disease free and overall survival for patients with osteosarcoma.

Patients and Methods: All patients had stage IIB osteosarcomas originating around the knee (distal femur, proximal tibia). Group A included 20 patients who underwent biopsy and were treated with neoadjuvant chemotherapy and surgical resection. Group B included 73 patients who underwent primary surgical resection of their tumor followed by postoperative chemotherapy. Tumors were evaluated with antibodies to bcl-2, p53, Fas, Fas-L, CD44, CD44v6, and p-glycoprotein using standard avidin-biotin complex methods. Expression of the various antigens was compared to disease-free and overall survival, accounting for percent necrosis (Group A) and margin status (Groups A & B).

Results:

Conclusions: CD95 appears to have a “protective” function in patients with osteosarcoma, probably by allowing tumor cells to proceed through apoptosis pathways to cell death. Although CD44v6, a vascular adhesion molecule, was identified in only 14% of the total cases, its expression correlated with subsequent development of metastases and death (11 of 13 patients developed pulmonary metastases, 10 dying of disease). Although p-glycoprotein did not reach statistical significance, there was a trend toward death from disease in patients expressing it.