TTN and lung cancer: We observed that mutations in a subset of genes were almost always shared by both primary lung cancers and BrM lesions, including TTN (62%, 64%), MUC16 (46%, 45%), LRP1B (43%, 42%), TP53 (42%, 49%), OBSCN (26%, 25%), FAT3 (25%, 26%), and EGFR (22%, 20%), which were commonly mutated in lung cancers [49] (Fig. 2a,b and Additional file 2: Fig. S2a).