Nuclear immunoreaction of p53 protein in soft tissue sarcomas. A possible prognostic factor

Tumor suppressor gene p53, located on the short arm of chromosome 17, frequently mutates in various types of cancers and plays a critical role in the multiple stages of carcinogenesis. However, there is little information about the clinicopathologic significance of alterations of the p53 gene in soft tissue sarcomas (STS).

Because it is known that nuclear accumulation of p53 protein correlates closely with the presence of mutations in the p53 gene, immunohistochemical detection of this protein was performed. A polyclonal antibody (RSP-53) raised against synthetic human p53 peptide was used to detect nuclear accumulation of the protein. Pathologic specimens of 96 patients with STS were collected from the surgical pathology files of the National Cancer Center Hospital and examined.

Nuclear accumulation of p53 protein was detected in 31 (32.3%) patients. The percentage of patients with a positive immunoreaction was high in patients with malignant schwannoma (100%), rhabdomyosarcoma (71.4%), and synovial sarcoma (50.0%), whereas it was low in patients with liposarcoma (13.6%) and 0% in those with fibrosarcoma. It was closely associated with the histologic grade of malignancy (grade 1, 12.0%; grade 2, 30.8%; grade 3, 44.4%) and the patient's age (younger than 40 years, 46.9%; 40 years of age or older, 25.0%). Both overall and metastasis-free survival rates were significantly lower for patients with a nuclear p53 immunoreaction than for those without it.

The nuclear p53 immunoreaction is considered a marker of tumor aggressiveness and appears to be a useful prognostic factor for STS.