PurposeAnaplastic lymphoma kinase (ALK) mutations occurs in approximately 3-5% of patients with non-small cell lung cancer (NSCLC). Pleural involvement/effusion is common in ALK-positive patients with NSCLC at baseline. The aim of the study was to evaluate the characteristics of ALK-positive patients who have Ple-I/E.MethodsIn this multicenter study, patients with ALK-positive NSCLC who have Ple-I/E were retrospectively analyzed. Clinical and demographic characteristics of the disease, response rates, median progression-free survival (PFS), and overall survival (OS) were evaluated in 362 ALK-positive patients with NSCLC.ResultsOf the patients, 198 (54.7%) were male. The median age at the time of diagnosis was 54 (range 21-85) years. All patients' histology was adenocarcinoma (100%). At baseline, 57 (15.7%) patients had Ple-I/E. There was no association between Ple-I/E and gender, lung metastasis, or distant lymphadenopathy (LAP) metastasis. The frequencies of liver, brain, and bone metastases were significantly higher in ALK-positive patients without Ple-I/E compared to those with Ple-I/E (respectively 18.2% vs 4.8%, p = 0.008; 19.1% vs 4.8%, p = 0.001; 20.6% vs 8.9%, p = 0.002). The median PFS was longer in ALK-positive patients who had Ple-I/E (18.7 vs 10.6 months, p = 0.017). Similarly, the median OS was longer in ALK-positive patients who had Ple-I/E (44.6 vs 22.6 months, p = 0.051).ConclusionBrain, liver, and bone metastases were lower in ALK-positive patients with Ple-I/E. Patients presented with Ple-I/E were prone to have better PFS and OS.