Comparison of Epidermal Growth Factor Receptor Mutations between Primary and Corresponding Metastatic Tumors in Tyrosine Kinase Inhibitor-Naive Non -Small-Cell Lung Cancer

Background: Mutations of the epidermal growth factor receptor (EGFR) gene in non-small-cell lung cancer (NSCLC) patients predict the patients who will respond to EGFR tyrosine kinase inhibitor (TKI) treatment. A recent study has suggested that 33% of NSCLC showed primary tumor/ metastasis discordance of EGFR expression by immunohistochemistry analysis. We intended to find out whether the EGFR mutations of primary lung cancers are concordant to that of corresponding metastatic tumors. Materials and methods: We analyzed EGFR exons 18-21 from paired primary and metastatic tumors in 67 lung cancer patients who had not received TKI before tissues were sampled. Results: Using the direct sequencing method, 9 of 18 (50%) patients with EGFR mutation-positive primary lung tumors had lost the mutations in metastases. For 26 patients who were EGFR mutation positive in the metastatic tumors, 17 (65%) were negative in the primary tumors. We analyzed these paired tissues with discrepant EGFR mutations by the Scorpion Amplified Refractory Mutation System assay. Finally , the discordant rate reached 27% (18 of 67 cases). Conclusion: EGFR mutations in primary lung tumors do not always reflect the same situation in metastases. Analysis of EGFR mutations in the primary lung tumor would be inadequate for planning the use of TKI for advanced NSCLC

Multidriver mutation analysis in pulmonary mucinous adenocarcinoma in Taiwan: identification of a rare CD74-NRG1 translocation case

Several new chromosomal translocations resulting in driver fusion mutations have recently been discovered in non-small-cell lung cancer. The driver mutational patterns in pulmonary mucinous adenocarcinoma, a rare subtype of non-small-cell lung cancer, have not been well studied. A single-institute cohort study in Taiwan was performed to determine the mutations of epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), fusions of anaplastic lymphoma kinase (ALK), c-ros oncogene 1 (ROS1), and neuregulin 1 (NRG1) in patients diagnosed with pulmonary mucinous adenocarcinoma. We also examined NRG1 translocation in patients diagnosed as adenocarcinoma of other subtypes with wild-type EGFR, KRAS, ALK, and ROS1 genes. Surgical or biopsy specimens were collected from 13 patients with mucinous adenocarcinoma. Using the direct RNA sequencing method, we discovered a rare CD74-NRG1 fusion (8 %), an echinoderm microtubule-associated protein like 4 (EML4)-ALK fusion (17 %), and three KRAS mutations (25 %). No EGFR mutations or ROS1 rearrangements were detected. The rare CD74-NRG1 fusion positive patient presented with uncommon radiological features. We did not detect any CD74-NRG1 fusion in the 109 adenocarcinoma of other subtypes, which were all negative for EGFR, KRAS, ALK, and ROS1. The CD74-NRG1 fusion mutation is rare and may be exclusively present in patients with pulmonary mucinous adenocarcinoma. Patients harboring CD74-NRG1 positive tumors may present with uncommon imaging features