Differential expression of EGFR mutations between primary and corresponding mediastinal nodal metastases in postoperative stage N2 non-small cell lung cancer.

Abstract

e21034 Background: In this retrospective study, we determined the differential expression of EGFR mutations between primary tumors and the corresponding mediastinal nodal metastases, and the differential expression of EGFR mutations between different lymph node stations in postoperative stage N2 non-small cell lung cancer (NSCLC). Methods: In this retrospective study, we determined the differential expression of EGFR mutations between primary tumors and the corresponding mediastinal nodal metastases, and the differential expression of EGFR mutations between different lymph node stations in postoperative stage N2 non-small cell lung cancer (NSCLC). Results: In all 28 cases with N2 disease which had EGFR mutations in primary tumors, EGFR mutations were detected in 33 of all 70 metastatic lymph node stations (47.14%) and in 17 cases (60.71%) who had EGFR mutations in metastatic lymph nodes. Among the 17 cases, 15 were mutations in mediastinal lymph nodes, while 2 were mutations in N1 lymph nodes. Thirteen of 28 cases (46.43%) showed discordance in EGFR mutations between primary tumors and mediastinal nodal etastases. Among the 28 cases, 21 had at least two of metastatic lymph node stations and 7 had just one metastatic lymph node station. Nine of 21 cases (42.86%) with multiple metastatic node stations exhibited discordance in EGFR mutations btween different lymph node stations. Conclusions: EGFR mutations were discordant between the primary tumor and the corresponding mediastinal nodal metastases in patients with stage N2 NSCLC, and the mutations were also discordant between different lymph node stations.