In patients with lung cancer and BM, the most frequently altered genes in the CSF were EGFR (84.0%), TP53 (60.6%), MET (24.5%), CDKN2A (23.4%), MYC (21.3%), NTRK1 (20.2%), and CDK6 (16.0%).[42] Zheng et al.[43] reported similar results, with enrichment of MYC, CDKN2A, STK11, NTRK1, TP53, SMAD4, RB1, CDK6, CDK4, and MET in CSF ctDNA. Here, CDKN2A is linked to lung cancer.