Tumor samples originating from clinically considered multiple or multifocal primary lung cancer patients were available for mutational analysis. DNA and RNA were extracted from fresh tumor tissue or formalin-fixed, paraffin-embedded (FFPE) tissue. A series of cancer-related genomic alterations including single nucleotide variations (SNVs), short insertions and deletions (InDels), copy number variations (CNVs) and gene rearrangements were identified by a comprehensive NGS Panal . High frequency mutations were also identified in blood sample by droplet digital polymerase chain reaction(ddPCR).