Inclusion Criteria:  Patients older than 18 years; Newly diagnosed advanced stage IIIB-IV NSCLC (AJCC 8th edition) or locally advance/distant relapse in the period of January 2015 to December 2020. NSCLC with pathological confirmation of ALK rearrangement by immunohistochemistry, fluorescent in situ hybridization (FISH) or next generation sequencing (NGS); ECOG 0-4; Patients with CNS metastases are also considered eligible, regardless of the initial treatment instituted.  Exclusion Criteria:  - Incomplete medical chart in terms of date of diagnosis, ALK test results and outcomes