Evaluation of epidermal growth factor receptor (EGFR) in nasopharyngeal carcinoma and lymph node metastases: Implications for EGFR targeted therapy

Abstract

16510 Background: Epidermal growth factor receptor (EGFR) overexpression is proved to be an independent predictor of poor clinical outcome in Nasopharyngeal Carcinoma (NPC). Expression level of EGFR is also important for EGFR-Targeted therapy but yet unexplored in the primary NPC tumors and lymph node metastases. Aim of this study was to correlate EGFR expression levels in primary tumors and lymph node metastases in NPC to find out whether assessing EGFR status on primary cancer is an effective tool for planning EGFR targeted therapy. Methods: Archived tissue samples of primary tumor and corresponding lymph node metastases of 86 NPC patients (67 males, 19 females; median age = 52 years) diagnosed between 1997 and 2006 were collected from Sun Yat-sen University Cancer Center. Immunohistochemical evaluation of EGFR expression in primary tumors and related lymph node metastasis was performed. According to the UICC 2002 staging system for nasopharyngeal carcinoma, stages Iib, III, IVa, IVb and IVc included 43, 11, 3, 27 and 2 cases respectively. Cervical and supraclavicular lymph nodes were taken in 66 (76.7%) and 20 patients (23.3%) respectively. EGFR status was defined as positive if the percentage of malignant cells stained were =1%. The SPSS 10.0 system was used for statistical analysis and Chi- square test was used to assess the correlation between the EGFR expression in the primary and metastatic tumors. Results: EGFR status was positive in 63 primary tumors (73.2%) and 52 metastatic lymph nodes(60.5%). In 18 EGFR expressing primary tumors (28.6%), the corresponding metastatic lymph node site was negative whereas it was found positive in 7 metastic lymph node (13.5%) of EGFR-negative primary tumors. The difference between these two groups (ie, EGFR-positive to EGFR-negative vs. EGFR-negative to EGFR-positive) was statistically significant (P=0.001). Conclusions: High levels of EGFR protein are frequently observed in NPC and represent potential therapeutic target. However, equivalent expression is not displayed by metastatic nodes, which may limit the effectiveness of anti- EGFR treatment in advanced diseases. These findings have to be considered in future prospective studies. No significant financial relationships to disclose.