Coexistence of HER2, Ki67, and p53 in Osteosarcoma: A Strong Prognostic Factor.

Background: Many laboratories are currently evaluating the usefulness of the determination of human epidermal growth factor receptor 2 (HER2), p53, and Ki67 proliferation indices using immunohistochemical techniques in cancer. Although the available studies suggest that these factors might indeed be helpful in making treatment decisions in osteosarcoma patients, their clinical usefulness is still controversial.

Aims: We proposed to introduce the value of the coexistence of HER2 overexpression, p53 protein accumulation, and Ki67 in osteosarcoma, which could be a prognostic factor in osteosarcoma.

Material and methods: Expression of HER2, p53, and Ki67 was examined by immunohistochemistry in samples of resected bone tumor tissue from 56 patients with osteosarcoma, obtained between 2009 and 2014 (median follow-up period of 48 months), and their significance for prognosis was analyzed.

Results: Of the 56 osteogenic sarcoma tissue samples, 80, 89, and 96.5% were positive for HER2 overexpression, p53 protein accumulation, and Ki67 expression, respectively. Overexpression of HER2 and accumulation of p53 protein significantly correlated with reduced disease-free (P < 0.01) and overall survival (P < 0.003). HER2 and Ki67 co-overexpression significantly correlated with decreased disease-free (P < 0.03) and overall survival (P < 0.02). HER2, accumulation of p53 protein, and Ki67 co-overexpression significantly correlated with reduced disease-free (P < 0.01) and overall survival (P < 0.005) as did patients with larger tumor size, high grade of tumor, positive lymph node, and metastasis status within the specified period of follow up.

Conclusions: We found evidence that coexistence of HER2 and Ki67 overexpression and p53 protein accumulation predict the development of lymph node involvement and metastases in patients with high-grade osteosarcoma and were significantly associated with reduced survival.