Prognostic Significance of p27 Expression in Carcinoma of the Oral Cavity and Oropharynx

Objective: To study the role of p27, a cyclin‐dependent kinase inhibitor, as a prognostic indicator in squamous cell carcinoma of the oral cavity and oropharynx. Study Design: Retrospective review of 35 patients with squamous cell carcinoma of the oral cavity and oropharynx who presented to Rush‐Presbyterian‐St. Luke's Medical Center, Chicago, Illinois, between 1986 and 1995. Methods: Inclusion criteria were the availability of clinical information, archival pretreatment biopsy material, and a minimum follow‐up of 24 months. p27 staining was scored for frequency and intensity of tumor cell expression following immunoperoxidase staining using standard techniques. Samples of squamous epithelium from the uvula of 15 nonsmoking patients without past or present squamous cell carcinoma were used as normal controls. Results: The association of p27 staining and other factors with response to treatment was evaluated by Fisher's Exact Test and with overall and disease‐free survival by the Kaplan‐Meier method with multivariate Cox regression. Low levels of p27 expression correlated significantly with unfavorable treatment response (P < .0001), shorter overall survival (P = .0001), and shorter disease‐free survival (P = .003). Tumor site (alveolus) was also associated with shorter disease‐free (though not overall) survival, but the association with p27 was independent of stage and site in multivariate analysis.