Ewing's sarcoma family of tumors (ESFT) is comprised of highly malignant bone and soft tissue tumors in children and young adults. Despite intensive treatments for patients with ESFT, disease which presents with metastatic spread or relapses after primary treatment remains incurable in the majority of cases, indicating the importance of efforts to develop new treatment modalities, including immunotherapy. The present study was designed to examine the expression profile of papillomavirus binding factor (PBF), which we previously defined as an osteosarcoma-associated antigen, and its prognostic significance for patients with ESFT. Biopsy specimens from 20 ESFT were stained with an anti-PBF antibody. Survival was estimated using Kaplan-Meier plots and the prognostic significance of several variables, including the expression status of PBF, on disease-free and overall survival was determined by univariate analysis using the log-rank test. Of 20 specimens, 18 (90%) reacted positively to the anti-PBF antibody. Fifteen specimens (75%) were graded as PBF overexpression. Of the 11 variables analyzed, stage III disease, inadequate surgical margins and PBF overexpression were significantly associated with decreased disease-free and overall survival. None of the other variables, including age, gender, origin of tumor, tumor site or levels of LDH, ALP, CRP and ESR, showed any significant association. These findings indicate that the overexpression of PBF is a factor indicative of poor prognosis in ESFT. PBF may also serve as a putative target antigen in immunotherapy for patients with ESFT that have a poor prognosis and PBF overexpression.

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