Background: Lung cancer remains the leading cause of death from cancer around the world. Several oncogenic drivers have been identified from large cancer genome projects focused mainly on profiling early-stage lung cancers. Targeted therapies have been developed for specific activated driver gene mutations and are used in advanced-stage patients. For instance, advanced EGFR mutant lung cancer is primarily treated with EGFR tyrosine receptor inhibitors (TKIs). However, resistance remains an obstacle to durable anti-tumor control. We hypothesize that concurrent genetic alterations co-exiting with EGFR driver mutations contribute to the failure of EGFR TKI therapy. Methods: To understand the complexity and diversity of genetic alterations present in EGFR mutant advanced lung cancers, we utilized 660 EGFR mutant advanced lung adenocarcinomas samples with targeted DNA sequencing from Foundation Medicine, 394 cases from MSK-IMPACT dataset, along with TCGA lung cancer data. We performed systematic co-mutation analysis, molecular simulation, functional annotation and pathway enrichment analysis. Results: We updated mutational profiling on EGFR gene with hotspots at exon 18, 19, 20 and 21. Among them, EGFR L858R, exon19 deletion, T790M and G719A are top ranking alleles among EGFR mutations. Interestingly, a subset (n = 26 cases) of EGFR T790M mutations parallel with other EGFR mutations, which could affect the TKI binding pocket as inferred by molecular simulations. Furthermore, in advanced lung cancer EGFR mutations co-occurred with known oncogenic mutations in KRAS, MET, NF-1, MAP2K1, ERBB2, and ALK/ROS-1/RET fusions. Functional annotation suggests that concurrent mutated genes and copy number alterations in advanced EGFR mutant lung cancer were enriched in signatures of epigenetic modifiers, genome instability, WNT signaling, and RNA splicing. Compared to early stage TCGA-lung adenocarcinomas, Cell cycle, DNA repair, WNT signaling and androgen receptor-mediated signaling pathways are predominantly altered in advanced EGFR mutant lung cancers. Conclusions: We characterized the genetic landscape of advanced EGFR-mutant lung adenocarcinomas and further dissected concurrent mutated genes with EGFR driver mutations. Our findings provide a rational for polytherapy roadmap for testing in advanced EGFR-mutant lung cancer.