BACKGROUND: Osteosarcomas (OS), the most frequent primary malignant bone tumors, have aggressive local behavior and high rate of metastatization. The events that allow tumor growth and dissemination are still controversial. The studies about carcinogenesis and tumor progression in this neoplasia, which are based on c-erb-B2, P-glycoprotein (P-gp) and p53 immunoexpression, show conflicting results as to the real prognostic value and its correlations with histological parameters. Anaplasia in childhood neoplasias is a histological parameter of tumor aggressiveness and chemoresistance. In primary or metastatic OS, its meaning remains controversial. On the other hand, in other human neoplasias, c-erb-B2 expression is associated with p53, nuclear grade and other aggressiveness parameters. OBJECTIVE: The aim of the present study was to evaluate p53, c-erb-B2 and P-gp immunoexpression in OS, correlating the parameters with the presence of anaplasia. METHODS: This study included 96 pre-chemotherapy biopsies in patients with high-grade OS diagnosed between 1991 and 2000. The immunohistochemical evaluation of p53 and c-erb-B2 was carried out with the streptavidin-biotin-peroxidase technique. Cases were considered positive when there was immunoexpression in 10% or more neoplastic cells. Only membrane staining (for c-erb-B2 and P-gp), and nuclear staining (for p53) were considered positive. Anaplasia was defined as Wilms' tumor, and considered present or absent. RESULTS: Anaplasia was present in 29 out of 82 cases (35.36%); p53 immunoexpression was detected in 25 out of 60 cases (36.23%); P-gp, in 30 out of 73 cases (41.1%); and c-erb-B2, in 22 out of 55 cases (40%). The results demonstrated an association between c-erb-B2 and p53 immunoexpression (p = 0.042), p53 and parameter of anaplasia (p = 0.015), anaplasia and P-gp (p = 0.034). CONCLUSIONS: The p53, c-erb-B2 and P-gp immunoexpression is relatively frequent in high-grade, metastatic and non-metastatic OS. The results reinforce the hypotheses that in the presence of anaplasia adverse events may occur simultaneously in this neoplasm. Anaplasia may become a histological marker for P-gp and/or p53 status in some high-grade OS, and it may indicate chemoresistance. There was no positive association between p53 and P-gp.
Osteosarcoma; Immunohistochemistry; Bone tumor; Bone neoplasm; Histological markers
