As of December 2022, 18 molecularly targeted drugs have been approved in Japan for eight gene mutations in lung cancer: epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), c-ros oncogene 1 (ROS1), v-Raf murine sarcoma viral oncogene homolog (BRAF), rearranged during transfection (RET), mesenchymal-epithelial transition factor (MET) exon 14 skipping, neurotrophic receptor tyrosine kinase (NTRK), and c-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS). The gene discussed is RET; the disease is lung cancer.