Immunohistochemical detection of p53 protein in rhabdomyosarcoma: association with clinicopathological features and outcome.

Purpose: Alteration in the p53 tumor suppressor gene is the most common tumor specific genetic change identified in most major cancer types including rhabdomyosarcomas. To investigate the overexpression of p53 and its relation to clinical features and outcome in patients with rhabdomyosarcoma (RMS), an immunocytochemical study was performed.
Methods: Formalin-fixed paraffin embedded tissue sections obtained from 42 cases of RMS were immunostained with a mouse monoclonal antibody p53-D07. Staining was assessed by evaluating the percentage of p53 immunopositive cancer cell nuclei.
Results: Nuclear accumulation of p53 protein was detected in 8 of 42 (19%) samples. Clinical analyses of patients demonstrated no correlation between positive staining and age, sex, histological subtype, stage and overall survival. This analysis, however, was limited by the small number of patients who demonstrated p53 immunostaining. Nonetheless, a statistically significant association was observed between p53 expression and adverse outcome. Nuclear p53 expression was associated with disease progression or recurrence (p <0.001) and with a worse event free survival (p = 0.0015).
Conclusion: The nuclear p53 immunoreaction rate is low in RMS, but p53 expression appears to correlate with poor prognosis.