Objective: To investigate gene mutations of epidermal growth factor receptor (EGFR) and K-ras in Chinese patients with non-small cell lung cancer (NSCLC) and its clinicopathological significance, and to analyze the correlation between these mutations and tumor response to erlotinib treatment.
Methods: Mutations of exons 18, 19, 20 and 21 of the EGFR and codons 12, 13 of the K-ras in 301 cases of NSCLC were detected by PCR-amplification and gene sequencing. The relationship between the mutations and clinicopathological characteristics of the 301 patients was analyzed.
Results: EGFR mutations were present in 32.9% (99/301) of the samples: 3 mutation in exon 18, 59 in exon 19, 2 in exon 20, and 35 in exon 21. Mutations of K-ras were present in 4.7% (14/301) of the samples: 13 in codon 12 and 1 in codon 13. EGFR mutations were never found in tumors with K-ras mutations, suggesting a mutually exclusive relationship. EGFR mutations were more common in adenocarcinomas, non-smokers and females. Seven out of 10 erlotinib-treated patients with disease control carried EGFR mutation.
Conclusion: The frequency of EGFR mutation in Chinese NSCLC patients is higher than that in Westerners, but the frequency of K-ras mutation is quite opposite. Combined detection of EGFR gene and K-ras gene mutation may help clinicians to choose patients who may gain benefit from EGFR tyrosine kinase inhibitor (EGFR-TKI) treatment, and to predict their response to erlotinib treatment and prognosis.