BACKGROUND: Somatic mutations in the epidermal growth factor receptor (EGFR) 
gene are associated with the responses to the tyrosine kinase inhibitors 
gefitinib and erlotinib in patients with non-small-cell lung cancer (NSCLC). 
Although various methods for detecting EGFR gene mutations have been developed, 
they have several disadvantages. We attempted to establish a new method for the 
detection of EGFR gene mutations with the use of paraffin-embedded samples.
METHODS: The detections of T790M mutations in exon 20 and L858R mutations in 
exon 21 are based on the principle of allele-specific oligonucleotide polymerase 
chain reaction (PCR). We also designed PCR primers that enable to detect all 
types of deletions in exon 19. We assessed the basic performance efficiency of 
this method, and to confirm its clinical applicability, we performed PCR using 
DNA extracted from 66 tissue sections that were obtained from patients with 
NSCLC and embedded in paraffin.
RESULTS: The sensitivity of this method for the detection of deletions or 
mutations was as low as 0.5%. In the 66 subjects whose samples were analyzed, we 
detected the following deletions and mutations in the EGFR gene: 11 deletions in 
exon 19, 8 L858R mutations, and 1 double mutation of L858R and T790M.
CONCLUSION: The present method is sensitive and specific for the detection of 
deletions and mutations in the EGFR gene and is thus suitable for use in 
laboratory tests.