Epidermal growth factor receptor mutation subtype has differential effects on adjuvant chemotherapy for resected adenocarcinoma pathological stages II–III

The aim of the present study was to investigate epidermal growth factor receptor (EGFR) mutations as a prognostic factor for postoperative patients with positive EGFR mutations treated with postoperative platinum-based adjuvant chemotherapy (PBAC), and whether two common EGFR mutations exhibit different responses to PBAC. A total of 110 patients who underwent complete surgical resection were enrolled, and overall survival (OS) and disease-free survival (DFS) were investigated based on EGFR mutation status and PBAC. The 3 year OS rate in patient groups were as follows: Patients with EGFR mutations (MT) undergoing PBAC, 89.3%; MT patients without PBAC, 83.3%; wild-type (WT) patients with PBAC, 82.3%; and WT patients without PBAC, 62.2%. Statistically significant differences were observed between WT patients based on PBAC (P=0.026). No statistically significant differences were observed between MT patients with PBAC and MT patients without PBAC. On the basis of mutation subtypes, the 3 year OS rate of patient groups were as follows: Patients with in-frame deletions in exon19 (19 del) with PBAC, 92.3%; patients with 19 del without PBAC, 85.7%; patients with the point mutation L858R inexon21 (21L858R) with PBAC, 86.7%; and patients with 21L858R without PBAC, 81.5%; the respective 3-year DFS rates were 53.8, 14.3, 40.2 and 26.9%. Statistically significant differences were observed in the DFS rates in 19 del patients, which was dependent on PBAC (P=0.040). EGFR mutation-positive patients exhibited a decreased benefit from PBAC for increasing in survival rate compared with WT patients. It may be necessary to consider postoperative strategies based on EGFR mutations and their subtype in the future.