Objective To investigate the expressions of epidermal growth factor receptor (EGFR)

cyclooxygenase-2 (COX-2) and P63 protein in non-small cell lung cancer (NSCLC) and their relationship with TNM staging and lymph node metastasis of NSCLC. Methods Seventy-eight paraffin-embedded specimens of NSCLC from 1998-2005 were collected in this study. Inclusion criteria included no chemotherapy or radiotherapy before operation. Pathological diagnosis was made after operation: 43 squamous carcinoma and 35 adenocarcinoma

45 with lymph node metastasis and 33 without

13 in stage Ⅰ

19 in stage Ⅱ

28 in stage Ⅲ and 18 in stage Ⅳ. The expressions of EGFR

COX-2 and P63 were determined by immunohistochemical staining (S-P). Results The expression rates of EGFR

COX-2 and P63 were 65.4% (51/78)

61.5% (48/78) and 56.4% (44/78) respectively in 78 cases of NSCLC. Significant difference in the expressions of COX-2 and P63 was found between squamous carcinoma and adenocarcinoma (P0.01). The expression of EGFR in NSCLC was not associated with histological types of NSCLC (P0.05). The positive rate of EGFR and COX-2 protein expressions in NSCLC of stage Ⅲ-Ⅳ and NSCLC with lymph node metastasis was significantly higher than that in stage Ⅰ-Ⅱ and NSCLC without lymph node metastasis (P0.01). The positive expression of P63 in NSCLC was not associated with TNM staging and lymph node metastasis (P0.05). Conclusion Overexpressions of EGFR and COX-2 may play an important role in invasion and metastasis of NSCLC. COX-2 and P63 may be valuable markers in differentiating pulmonary squamous cell carcinoma from pulmonary adenocarcinoma.