Clinicopathological Characteristics and Therapeutic Effect of Patients with Non-small Cell Lung Cancer and Uncommon EGFR Mutations

Objective To investigate the clinicopathological characteristics and treatment effect of patients with non-small cell lung cancer (NSCLC) and uncommon epidermal growth factor receptor (EGFR) gene mutations. Methods Real-time fluorescence quantitative PCR was used to detect the mutation of EGFR in 674 samples of patients with NSCLC.The correlation between uncommon EGFR mutations and clinicopathological characteristics was analyzed. Results The EGFR mutation rate was 47.92%, of which the incidence of uncommon EGFR mutations was 5.19%, showed the presence of ex18 G719 A/S/C (G719X)(1.63%), ex20ins (1.04%), ex21 L861Q (0.74%), and compound mutations (1.78%).Correlation analysis showed that uncommon EGFR mutations were more common in women, non-smokers, patients with high-medium differentiation and adenocarcinoma, and patients were more prone to brain and bone metastasis (all P < 0.05).NSCLC with uncommon EGFR mutations showed no significant differences in clinical and pathological features compared with those with common sensitive mutations (all P > 0.05).Follow-up information was available on 31 patients, with a median follow-up time of 10 months, of which 23 were in advanced stage.Among eight patients with G719X mutation in late stage, seven patients used EGFR tyrosine kinase inhibitor (EGFR TKIs)(five of them used afatinib) in the first line and had a median PFS of 12 months; one patient received chemotherapy with pemetrexed and carboplatin and had PFS of seven months, which was lower than that of the TKI group.Among four patients with L861Q mutation in late stage, one patient was untreated and the three remaining were treated with TKI in the first line and had a median PFS of eight months.The patient who was treated with afatinib and bevacizumab was still stable after 11 months of follow-up.Two patients with EGFR ex20ins in advanced stage were treated with chemotherapy and bevacizumab.Nine patients with compound mutations in advanced stage were treated with TKI; among which, five patients harboring T790M compound mutations were treated with third-generation TKI and had a median PFS of more than 10 months. Conclusion The correlation between specific uncommon EGFR mutation and clinical pathological characteristics varies.For advanced patients with uncommon EGFR mutations (except for ex20ins), TKI is generally chosen as the first-line clinical treatment.Afatinib is recommended for advanced NSCLC patients with G719X and L861Q mutations.Third-generation TKI has significant efficacy in patients with complex mutations containing T790M.