Abstract:

Objective To invistigate the discordance of epidermal growth factor receptor（EGFR） mutations between primary and brain metastatic tumors in non-small cell lung cancer（NSCLC）, and then analyze the consistency between them. Methods Thirty-one paired primary and brain metastatic tumors colleted from Jan. 2003 to Dec. 2011 were evaluated for the EGFR mutation by direct DNA sequencing and the cases of discordance of EGFR mutation were further detected by amplifyication refractory mutation system （ARMS）. Results In 31 case of primary tumors， 8 presented with deletions in exon 19 and 4 presented with L858R （leucine to arginine at codon 858） mutation in exon 21. In 31 case of brain metastatic tumors， 8 presented with deletions in exon 19 and 3 presented with L858R （leucine to arginine at codon 858） mutation in exon 21. There was no difference in distribution between the primary and brain metastatic tumors in NSCLC（P=0.793）.However， contrasted the primary and brain metastatic tumors individual through the ARMS， we found the EGFR gene mutation types were discordant in 5（16.1%） patients （4 male and 1 female）， including 3 adenocarcinoma （the brain metastatic tumors presented with deletions in exon 19 while the primary tumors presented with no EGFR gene mutation in 2 patients, and the primary tumor presented with L858R mutation in exon 21 while the brain metastatic tumor presented with no EGFR gene mutation in 1 patient）， 1 squamous-cell carcinoma and 1 atypical carcinoid （the primary tumors presented with deletions in exon 19 while the brain metastatic tumors presented with no EGFR gene mutation in both patients）. Conclusion EGFR mutations show discordance between the primary and the brain metastatic tumors in NSCLC.