ALK and non-small cell lung carcinoma: A total of 4622 advanced NSCLC patients from two institutes (3762 patients at Guangdong Lung Cancer Institute from 2011 to 2016 and 860 cases at Perking Cancer Hospital from 2015 to 2016) with complete electronic records were screened for ALK gene status, of whom 282 were identified with ALK rearrangement.