New P16 Expression Criteria Predict Lymph Node Metastasis in Patients With Non-small Cell Lung Cancer

Abstract

Background: There have been many attempts to predict the prognosis of lung cancer based on the expression patterns of P16 protein, but with limited success. The Eighth American Joint Committee on Cancer (AJCC) for head and neck cancer recently developed new criteria for evaluating P16 expression. Here, we applied these new criteria to evaluate the prognosis of non-small cell lung cancer (NSCLC). Materials and Methods: A total of 148 patients who had undergone surgery for NSCLC were enrolled in the study. P16 protein expression patterns from NSCLC tissue microarray samples were examined by immunohistochemical analysis. The Eighth AJCC head and neck cancer staging criteria were used to evaluate positive P16 expression (moderate/strong nuclear expression intensity and distribution >75% cells) in NSCLC. The relationship between P16 expression and clinicopathological factors were evaluated and survival analysis was included. Results: Negative P16 expression was significantly associated with NSCLC with lymph node metastasis (p=0.025). In addition, patients with NSCLC with negative P16 expression demonstrated poor disease-free and disease-specific survival in multivariate analysis. The Kaplan-Meier survival curve confirmed that negative P16 expression was significantly correlated with a poor disease-free survival (p=0.017) and disease-specific survival (p=0.016). Conclusion: P16 expression defined with the new AJCC criteria is useful for detecting lymph node metastasis in NSCLC.