Heterogeneity and Clinical Effect of Epidermal Growth Factor Receptor in Primary Lung and Brain Metastases of Nonsmall Cell Lung Cancer.

Introduction: This study aimed to analyze the heterogeneity in epidermal growth factor receptor (EGFR) gene mutation and its impact on clinical outcomes in primary tumor and corresponding brain metastasis (BM) in nonsmall cell lung cancer (NSCLC).

Materials And Methods: Primary pulmonary tumors and paired BMs of 27 NSCLC patients were surgically removed. All brain lesions were histologically confirmed as metastatic NSCLC. EGFR gene mutation status was detected by using amplification refraction mutation system. McNemar test was performed to compare EGFR mutation status between lung primary tumors and metastatic brain tumors and Kappa test was performed to quantify the agreement between the two.

Results: Of the 27 patients, nine cases were found to have EGFR mutations in BMs and 10 had a positive EGFR mutation status in primary lung tumor tissue. The rate of consistency of the matched tumor was 24/27 (88.9%). Among the three cases presenting EGFR mutational heterogeneity, two patients harbored an EGFR mutation in the primary tumor but not in the BMs; meanwhile, the last patient demonstrated the opposite pattern. Compared to patients with consistent EGFR mutations, patients with inconsistent mutations showed better outcomes. Further analysis revealed that the two patients whose EGFR mutant-type primary tumor progressed to wild-type cerebral metastatic tumor had longer overall survival than the patient whose EGFR wild-type primary tumor progressed to mutant-type brain metastatic tumor.

Conclusions: Heterogeneity of EGFR mutation status was observed between primary NSCLC and paired BM. Patients possessing a wild-type EGFR mutation in BM might have better outcomes, especially those with transition from mutant to wild-type.