Archival formalin-fixed, paraffin-embedded (FFPE) tumor specimens were collected from advanced NSCLC patients enrolled in LETS phase III trial comparing first-line S-1/carboplatin with paclitaxel/carboplatin and subjected to multiplex genotyping for 214 somatic hotspot mutations in 26 genes (LungCarta Panel) and 20 major variants of ALK, RET, and ROS1 fusion genes (LungFusion Panel) with the Sequenom MassARRAY platform. The gene discussed is RET; the disease is non-small cell lung carcinoma.