Radioresistance　is　the　major　cause　of　poor　prognosis　in　nasopharyngeal　carcinoma　(NPC).　To　identify　and　characterize　the　secretome　associated　with　NPC　radioresistance,　we　compared　the　conditioned　serum-free　medium　of　radioresistant　CNE-2R　cells　with　that　of　the　parental　radiosensitive　CNE-2　cells　using　isobaric　tags　for　relative　and　absolute　quantitation　(iTRAQ)　with　liquid　chromatography-electrospray　tandem　mass　spectrometry　(LC-ESI-MS/MS)　quantitative　proteomics.　Before　proceeding　to　quantitative　proteomics,　we　investigated　the　survival　curves　of　CNE-2R　and　CNE-2　cells　by　colony　formation　assay,　and　the　CNE-2R　survival　curves　were　significantly　higher　than　those　for　CNE-2.　In　total,　3,581　proteins　were　identified　in　the　quantitative　proteomics　experiments,　and　40　proteins　exhibited　significant　differences　between　the　CNE-2R　and　CNE-2　cells.　Twenty-six　of　the　40　proteins　were　secreted　by　classical,　non-classical,　or　exosomal　secretion　pathways.　To　verify　the　reliability　of　iTRAQ　quantitative　proteomics,　we　applied　western　blotting　(WB)　to　study　the　secretory　protein　expression　of　fibrillin-2,　CD166,　sulfhydryl　oxidase　1　and　cofilin-2,　which　are　involved　in　cell　adhesion,　migration　and　invasion.　The　WB　results　showed　that　fibrillin-2　(p=0.017)　and　sulfhydryl　oxidase　1　(p=0.000)　were　highly　expressed　in　the　CNE-2　cells,　while　CD166　(p=0.012)　and　cofilin-2　(p=0.003)　were　highly　expressed　in　the　CNE-2R　cells,　which　was　in　accordance　with　iTRAQ　quantitative　proteomics.　Finally,　a　phenotypic　subset　of　CD166-positive　NPC　cells　was　verified　by　immunocytochemistry.　In　summary,　we　defined　a　collection　of　secretory　proteins　that　may　be　relevant　to　the　radioresistance　in　NPC　cells,　and　we　determined　that　CD166,　which　is　widely　used　as　a　positive　marker　of　cancer　stem　cells,　is　expressed　in　NPC　cells.