EGFR and lung cancer: Approximately 3%–4% with advanced non–small cell lung cancer (aNSCLC) are diagnosed with LMD, and it occurs with a higher frequency in the adenocarcinoma subtype.1 The incidence rises to approximately 9% in patients with epidermal growth factor receptor (EGFR)-mutated NSCLC2; however, autopsy studies suggest LMD is frequently underdiagnosed.3,4 The survival for patients with aNSCLC associated with LMD is dismal, with a median overall survival (OS) of 3–11 months from diagnosis.1,2,5