Inducible Nitric Oxide Synthase Expression in Pharyngeal Squamous Cell Carcinoma: Relation to p53 Expression, Clinicopathological Data, and Survival†

Objective To investigate the expression of inducible nitric oxide synthase (iNOS) in oropharyngeal and hypopharyngeal squamous cell carcinoma (SCC) and its relation to p53 expression, histologic differentiation, clinical data, and prognosis. Study Design A retrospective survey. Methods Primary tumors for analyses were obtained from 118 patients diagnosed with SCC of the oropharynx or hypopharynx between 1975 and 1998 in eastern Finland. Immunohistochemical analysis was used to evaluate the expression of iNOS and p53. The expression pattern of iNOS was related to p53 expression, clinical data, and survival. Results High iNOS score was associated significantly with high nuclear p53 expression index (P = .006) and positive cytoplasmic p53 expression (P =.025). The score for iNOS expression was significantly lower in the largest (T4) tumors (P = .043). No association was seen between iNOS score and N or M class, tumor stage, or histologic differentiation. The score for iNOS expression was not related to overall survival. Conclusions The expressions of iNOS and p53 seem to be inter-related in pharyngeal SCC, although the causality remains to be clarified. The expression of iNOS shows no prognostic value in pharyngeal SCC.