Clinical Characteristics and Outcomes of Lung Cancer Patients 
with EGFR Mutations in Exons 19 and 21

Abstract

Background and objective Studies on the epidermal growth factor receptor (EGFR) signaling pathways and the therapeutic effects of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have recently proven that targeted therapy has a major role in the treatment of lung cancer. However, the therapeutic effects of EGFR-TKIs on lung cancers with different EGFR mutation subtypes remain unclear. And if there is a significant difference in the effects of EGFR-TKIs, the mechanisms for the difference remain unclear. The aim of this study was to investigate the clinical importance of EGFR mutations in exons 19 and 21 of lung cancer patients and to compare the outcomes of these patients. Methods The study recruited 113 patients who had non-small cell lung cancer (NSCLC) with EGFR mutations. EGFR mutations were detected for 47 patients using Real-time PCR or DNA sequencinag. The mutations of the remaining patients were determined using xTag-EGFR liquid chip technology. All stages I-III patients underwent radical resection followed by 4 cycles of postoperative chemotherapy. Patients with pleural metastases underwent pleural biopsy, pleurodesis, and chemotherapy only. Patients with distant metastases underwent biopsy and chemotherapy only. Collected clinical data were analyzed using SPSS 19.0 software. Results EGFR exon mutations 19 and 21 were found in 56 and 57 patients, respectively. The mean age of patients with exon 19 mutations was lower than the age of the patients with exon 21 mutations (57.02±11.31 years vs 62.25±7.76 years, respectively; P0.05) between the patients with exon 19 and 21 mutations; and survival analysis of 91 (80.5%) patients with complete clinical data found no differences in overall survival. Stratification analysis found out that patients with exon 19 mutations had longer overall survival associated with age>61 years, male gender, ever smoking, and stage IV disease; although the differences were not significant. Conclusion Compared to the lung cancer patients with EGFR exon 21 mutations, the patients with EGFR exon 19 mutations were younger, and their primary tumors were more likely to occur in the right lung. There were no significant differences between the lung cancer patients with exon 19 and 21 mutations for overall survival, gender, smoking status, histopathology, level of differentiation, and disease stage.

Keywords

• Lung neoplasms
• EGFR
• Target therapy
• Prognosis