Introduction: Ewing’s sarcoma is the second commonest primary tumor in childhood and its 5-year survival is currently just over 70%. The aim of the current study was to identify the prognostic significance of p53 and hsp70 overexpression into the nuclei of tumor cells.

Method: 30 patients treated for Ewing’s in a 15-year period, in a Children’s hospital, were included in the study. Treatment protocols included always Neo-adjuvant Chemo and did not considerably change in time. The male to female ratio was 1.8: 1. The average age was 10.5 years (range 2–18y). Central axis and extremities were equally affected, with pelvis being the commonest site. Expression of P53 and HSP70 in > 20% and > 15% of the tumor nuclei respectively, was considered compatible with mutation. The mean follow up was 7.2 years.

Results: Seventeen patients eventually died. HSP70 trace was negative, meaning that at the time of biopsy the tumor nuclei were not expressing the protein. Mutated p53 was traced in 13% of the tumor nuclei and had significant negative prognostic value in 5-year survival (p=0.039) and in Event Free Survival (p=0.006).

Discussion: The search of factors that could independently affect the prognosis in Ewing’s sarcoma continues. Identification of these factors would lead to application of more intense therapeutic means only to those patients with a poorer prognosis without getting everyone in the risk of adverse effects.