Human pathology
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In primary lung adenocarcinoma, EGFR and KRAS mutations are found in approximately 10% to 20% and 20% to 30%, respectively. Few studies have investigated these mutations in metastases. Patients with EGFR mutations have a 70% to 80% response rate to tyrosine-kinase inhibitors therapy and a longer progression-free survival rate in contrast to patients with KRAS mutations that are associated with virtually no response tyrosine-kinase inhibitors. ⋯ Of 9 pairs, mutations were concordant in 77.8%; 1 pair displayed acquisition of KRAS mutation, whereas 1 pair showed loss of EGFR mutation in the corresponding metastasis. Our findings suggest that EGFR and KRAS status should be tested in metastasis regardless of known mutations of the primary tumor. Additional studies are needed to further investigate the mechanisms of discordances in metastatic tumors.