Tumor samples were analyzed for : epidermal growth factor receptor ( EGFR ) expression ( immunohistochemistry -LSB- IHC -RSB- ) ; EGFR gene copy number ( fluorescence in-situ hybridization -LSB- FISH -RSB- ) ; EGFR mutations ( exon @ deletions/L@R mutations ) ; and KRAS mutations ( exons @/@ ) .