EGFR and leptomeningeal metastasis: Besides, CSF cfDNA could enhance the diagnostic validity for EGFR genotyping of LUAD patients with BM [10], and reveal frequent occurrence of uncommon EGFR mutations (G719A, L861Q, L703P, and G575R) in patients with leptomeningeal metastasis (LM, 54.5%) than brain parenchymal metastasis (BPM, 10%) [11].