Epidermal Growth Factor Receptor Genotype in Plasma DNA and Outcome of Chemotherapy in the Chinese Patients with Advanced Non-small Cell Lung Cancer

Background: The genotype of epidermal growth factor receptor (EGFR) is associated with tyrosine kinase inhibitor and effectiveness of therapy, but its role in cytotoxic chemotherapy is still unknown. Previous studies indicated that certain EGFR mutations were associated with response and progression free survival following platinum based chemotherapy. Our recent studies have identified that EGFR genotypes in the tumour tissues were not associated with response to the first-line chemotherapy in Chinese patients with advanced non-small cell lung cancer (NSCLC). In this study, we investigated associations of EGFR genotypes from plasma of patients with advanced NSCLC and response to first-line chemotherapy and prognosis.

Methods: We enrolled 145 advanced NSCLC patients who had received first-line chemotherapy in our department. We examined plasma EGFR genotypes for these patients and associations of EGFR mutations with response to chemotherapy and clinical outcomes.

Results: There were 54 patients with known EGFR mutations and 91 cases of wild types. No significant difference was detected in the response rate to first-line chemotherapy between mutation carriers and wild-type patients (37.0% vs. 31.9%). The median survival time and 1-, 2-year survival rates were higher in mutation carriers than wild-types (24 months vs. 18 months, 85.7% vs. 65.7% and 43.7% vs. 25.9%, P = 0.047). Clinical stage (IV vs. IIIb), response to the first-line chemotherapy (partial vs. no) and EGFR genotype were independent prognostic factors.

Conclusion: Plasma EGFR mutations in the Chinese patients with advanced NSCLC is not a predictor for the response to first-line chemotherapy, but an independent prognostic factor indicating longer survival.