EML4 and non-small cell lung carcinoma: Molecular targeted therapy has gradually become an important treatment for lung cancer, the aim of this research is to analyze the clinicopathologic features associated with the gene mutation status of epidermal growth factor receptor (EGFR), echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK), ROS proto-oncogene 1, receptor tyrosine kinase (ROS1) and Kirsten rat sarcoma viral oncogene (KRAS) in non-small cell lung cancer (NSCLC) patients and determine the most likely populations to benefit from molecular target therapy treatment.