The occurrence of brain metastasis in ALK‐positive patients was significantly higher than double‐negative ones both at baseline (26.5% vs. 16.5%, P = 0.038) and during treatment (25.8% vs. 11.9%, P = 0.003), but opposite for pleural effusion (6.2% vs. 26.9%, P < 0.001 at baseline; 3.1% vs. 10.3%, P = 0.031 during treatment). The gene discussed is ALK; the disease is Pleural effusion.