A Case of BRAF-V600E Mutation-positive Metachronous Secondary Lung Cancer Detected by Bone Metastatic Lesion

Background. Among the driver genes for lung cancer, the BRAF mutation is rare, with an incidence reportedly ranging from 0.8 to 1.6%. Case. A 67-year-old man was diagnosed with metachronous secondary lung cancer. At 15 years after the first lung cancer resection, he presented with multiple bone metastases and underwent a biopsy of the sixth rib, which showed an increased fluorodeoxyglucose (FDG) uptake. The biopsy specimens were analyzed by genetic testing with the cancer gene panel examination using next-generation sequencing. The BRAF-V600E mutation was identified, leading to BRAF inhibitor and MEK inhibitor combination treatment. Conclusion. Molecular-targeted drugs were effective against BRAF lung cancer.