Epidermal growth factor receptor mutations in primary tumors, N2 lymph nodes, and plasma samples in Chinese patients with stageⅢA-N2 non-small cell lung cancer / 中国肿瘤临床

ABSTRACT

Objective:Mutations in epidermal growth factor receptor (EGFR) can predict tumor response to tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC). However, not all cases of NSCLC with EGFR mutations can respond well;thus, discovering the heterogeneity of NSCLC at the molecular level is necessary. This study aimed to determine the discrepancy in EGFR mutations in primary tumors, N2 lymph nodes, and plasma samples. Methods:Primary tumors, N2 lymph nodes, and plasma samples obtained from 49 patients with stageⅢA-N2 NSCLC were analyzed for EGFR mutations in exons 19 and 21 by using mutant-enriched liquidchip technology. Results:In 49 patients, we detected 18 (36.7%) EGFR mutations in primary tumors, 11 (22.4%) mutations in N2 lymph nodes, and 2 (4.1%) mutations in plasma samples. Eleven (22.4%) cases showed discordance in EGFR mutations between primary tu-mors and N2 lymph nodes. In nine cases, EGFR mutations were detected only in primary tumors, whereas EGFR mutations were de-tected only in N2 lymph nodes in two cases. In addition, EGFR mutations were detected in the plasma samples of two patients, who al-so carry mutations in their primary tumors. Conclusion:A considerable proportion of NSCLC cases showed discrepancy in EGFR muta-tions between primary tumors and N2 lymph nodes. In addition, the detection rate of EGFR mutations was lower in plasma samples obtained from patients with stage IIIA-N2 NSCLC. All of the results indicated tumor heterogeneity at the molecular level during metas-tasis, and this heterogeneity may have implications during treatment with TKIs.