Epidermal growth factor receptor, cyclooxygenase-2, and BAX expression in the primary non-small cell lung cancer and brain metastases

Abstract

Purpose: The purpose is to identify biological markers that predict brain metastasis and treatment outcome in non-small cell lung cancer (NSCLC).

Experimental design: Samples were obtained from the primary tumors, lymph nodes, and brain metastases of 29 patients with NSCLC who had undergone resection of both the pulmonary tumors and the brain lesions. Samples from 29 patients matched for age, sex, and histology whose pulmonary tumors were resected served as controls. Samples were stained with H&E as well as immunohistochemical stains for epidermal growth factor receptor (EGFR), cyclooxygenase 2 (COX-2), and BAX. Comparisons were made between patients with and without brain metastasis. Independent investigators determined the percentage of positive cells.

Results: There was positive correlation in expression of all three biomarkers between primary lung tumors and lymph node metastases. Significantly higher levels of EGFR were found in lymph node metastases in the control group (P = 0.0147). COX-2 expression in brain lesions correlated with expression in primary tumors (P = 0.023). BAX levels were lower in poorly differentiated tumors in lymph node metastases in the control group (P = 0.01) and in brain metastases (P = 0.045). Low EGFR expression and high COX-2 expression in lymph node metastasis were associated with poorer treatment outcome.

Conclusions: Expression of EGFR, COX-2, and BAX in primary lung tumors did not differ between patients with brain metastases from NSCLC and those without brain metastases. These three biomarkers cannot be used to predict brain metastasis. Studies of other biomarkers are under way in an effort to predict brain metastasis among patients with NSCLC.