Nuclear and cytoplasmic p53 expression in pharyngeal squamous cell carcinoma: prognostic implications

The role of p53 expression in human neoplasms is still controversial, and it has been associated with both favorable and unfavorable outcome of the patients. Also cytoplasmic expression of p53 protein has been reported to affect survival in some cancers. Furthermore, an association between p53 and beta-catenin expression has been demonstrated. We studied the expression of p53 in a large group of oropharyngeal and hypopharyngeal squamous cell carcinomas and its relation to catenin expression, histologic differentiation, clinical data, and prognosis.

Primary tumors for analyses were obtained from 123 patients diagnosed with squamous cell carcinoma of the oropharynx or hypopharynx between 1975 and 1998 in Eastern Finland. Immunohistochemistry was used to evaluate the expression of p53 as well as alpha-, beta-, and gamma-catenins.

In the primary tumors (n = 123), the nuclear p53 expression index was low in 42 (34%), intermediate in 38 (31%), and high in 43 (35%) cases. Cytoplasmic p53 expression was present in 56 (46%) and absent in 67 (54%) tumors. In univariate analyses (Kaplan-Meier), hypopharyngeal primary site (p =.02), high T class (p <.0005), presence of distant metastases (p =.02), low Karnofsky performance index (p <.0005), high nuclear p53 expression index (p =.01), and positive cytoplasmic p53 expression (p =.04) predicted poorer overall survival (OS). In Cox proportional hazards model, only T class (p =.0005), Karnofsky performance index (p =.005), and nuclear beta-catenin expression (p =.038) predicted poorer OS.

Positive cytoplasmic p53 expression and nuclear p53 overexpression seem to relate to more aggressive features and unfavorable outcome in pharyngeal squamous cell carcinoma (PSCC). However, unlike more traditional variables, p53 expression is not an independent predictor of disease outcome in PSCC.