The role of protein p16 INK4a in non-oropharyngeal head and neck squamous cell carcinoma in Southern China.

Cyclin-dependent kinase inhibitor 2A (p16(INK4a)) protein is a surrogate immunohistochemical marker of human papillomavirus infection in oropharynx squamous cell carcinoma (OPSCC). However, the effects of p16(INK4a) in non-OPSCC require additional analysis. In addition, major gaps remain in the literature, including small volumes of data for China. Therefore, the present study evaluated the frequency of p16(INK4a) positivity in patients with non-OPSCC in Southern China, and assessed its prognostic value. p16(INK4a) expression status in patients with non-OPSCC was determined by immunohistochemistry. p16(INK4a)-positive expression was defined as a strong and diffuse staining in >= 70% of the tumor cells. Then, the diagnostic value of p16(INK4a) in predicting overall survival (OS) and disease-free survival (DFS) rate was determined. The positive rate of p16(INK4a) was 26.3% in larynx cancer and 24.8% in oral cavity cancer. Multivariate analysis revealed that the protein status independently predicted improved OS rate, but not DFS rate (P=0.096). Comparing different disease stages, patients at an early stage with p16(INK4a)-positive non-OPSCC exhibited improved DFS and OS rates compared with those exhibited by patients who were negative. The p16(INK4a)-positive rate in patients with non-OPSCC was 25.1% [26.3% in Laryngeal squamous cell carcinoma (LSCC) and 24.8% in Oropharyngeal squamous cell carcinomas (OSCC)] in the present cohort from South China. The present study suggested that p16(INK4a) expression in non-OPSCC predicts favorable clinical outcomes, particularly in early stage non-OPSCC and oral cancer.