Biological Characteristics And EGFR-TKIs Response In Lung Adenocarcinoma Associated With The EGFR Mutation And Its Subtypes

Background and ObjectivesMutation in the epidermal growth factor receptor (EGFR) is frequently seen in non-small cell lung cancers (NSCLCs), especially in adenocarcinoma. In this study, we investigated the impact of biological characteristics on the mutation of EGFR and its subtypes in advanced lung adenocarcinoma. Then the therapeutic effects of two different EGFR-TKIs (gefitinib and erlotinib) associated with the EGFR mutation subtypes will be compared.MethodsFrom2009Sep to2011Feb,169patients suffered from lung adenocarcinoma with clinical stage â…¢B or IV in xiangya hosipital were screened for EGFR mutations. Mutation status and its subtypes were compared with individual clinicopathologic features, such as sex, age, smoking, environmental tobacco exposure, cooking oil fumes, tumor differentiation, biopsy site (primary tumor/metastasis). In them,60patients with EGFR mutation(del19or L858R), were eligible,who received gefitinib or Erlotinib as First-line therapy. The therapeutic effects of erlotinib and gefitinib associated with the EGFR mutation subtypes(del19or L858R) were analyzed.Result EGFR mutation was significantly more frequent in nonsmokers (56.25%) than smokers (40%, P<0.05), in non-environmental tobacco exposure(58.7%) than environmental tobacco exposure(37.7%, P<0.05), in cooking oil fumes exposure(70.7%) than non-cooking oil fumes exposure(36%, P<0.05), in primary tumor(52.5%) than metastasis(32.1%, P<0.05) and in well-differentiated tumors (63.6%) than moderately and poorly differentiated tumors (25.7%, P<0.05). There existed correlation between EGFR mutations and cooking oil fumes exposure (P=0.001OR=4.561,95%CI (1.810,11.492)), well-differentiated tumors (P=0.035OR=1.870,95%CI(1.045,3.346))59patients with EGFR mutation(del19or L858R) received gefitinib (n=37) or erlotinib (n=23) in stage â…¢b or IV of advanced lung adenocarcinoma. Patients with EGFR del19mutant were related moe closely with PFS after TK inhibitors treatment compared with EGFR L858R mutant. In both groups with EGFR mutant del19and L858R, the effectiveness of gefitinib and erlotinib, including drug response or PFS, were not different significantly.Conclusion:1. Both cooking oil fumes exposure and tumor differentiation can influence the EGFR mutational spectrum. Our findings suggested EGFR del19mutation was presented more frequently in well-differentiated tumors. 2. The patients, suffered from advanced lung adenocarcinoma in stage â…¢b or IV then received gefitinib or erlotinib can get longer PFS with EGFR mutation del19than with L858R,.Both of the two EGFR mutantion subtypes can benefit from gefitinib or erlotinib targeted therapy. There is no different PFS in patients with all EGFR mutantion subtypes received gefitinib or erlotinib.