EGFR and lung adenocarcinoma: Pemetrexed (combined with cisplatin or carboplatin) is the first-line agent for lung adenocarcinoma according to the National Comprehensive Cancer Network guideline for NSCLC, Version 1.2020[5]; nevertheless, the efficacy of this traditional chemotherapy regimen in EGFR-negative, nonsquamous NSCLC patients with BM is somewhat uncertain.