[A Case of Multiple Brain Tumors Successfully Diagnosed with Liquid Biopsy and Treated with Osimertinib].

A seventy‒year‒old man complaining of left arm weakness and gait disturbance was diagnosed with multiple tumors and severe edema in the brain as well as right lung mass lesion, suggesting brain metastases. He started whole brain radiation therapy but had to discontinue it since his neurological symptoms were worsened including paralysis, aphasia, and coma. These symptoms made it difficult to perform tumor biopsy for cancer diagnosis as well as oncogene mutations.