Prognostic factors for relapse-free survival in stage IB-IIIA primary lung adenocarcinoma by epidermal growth factor receptor mutation status

BACKGROUND: Pathological stage IB-IIIA lung adenocarcinoma with an epidermal growth factor receptor (EGFR) mutation (Mt) has a high recurrence rate even after complete resection. However, there have been few reports on the risk factors for Mt recurrence. This study aimed to analyze the clinicopathological factors related to the relapse-free survival (RFS) of patients with pathological stage IB-IIIA primary lung adenocarcinoma with and without an EGFR mutation. METHODS: Patients who underwent curative surgery for Mt (n = 208) harboring the EGFR exon 21 L858R point mutation or EGFR exon 19 deletion mutation and EGFR mutation wild-type lung adenocarcinoma (Wt, n = 358) between January 2010 and December 2020 were included. Patients who received adjuvant EGFR-tyrosine kinase inhibitors were excluded. The prognostic factors for RFS were analyzed using a multivariable Cox regression analysis. RESULTS: The 5-year RFS rates in the Mt and Wt groups were 43.5 and 52.3%, respectively (p = 0.907). Prognostic factors for RFS in the Mt group included smoking history (hazard ratio [HR], 1.49; p = 0.049), blood vessel invasion (HR, 1.84; p = 0.023), and lymph node metastasis (HR, 1.96; p = 0.005). However, adjuvant chemotherapy was not a prognostic factor (HR, 1.02; p = 0.906). In contrast, positron emission tomography (PET) max standardized uptake value (SUV) ≥ 6.0 (HR, 1.53; p = 0.042), lymphatic vessel invasion (HR, 1.54; p = 0.036), lymph node metastasis (HR, 1.79; p = 0.002), and adjuvant chemotherapy (HR, 0.60; p = 0.008) were prognostic factors for RFS in the Wt group. CONCLUSIONS: Prognostic factors for RFS in stage IB-IIIA primary lung adenocarcinoma differ by epidermal growth factor receptor mutation status. The impact of adjuvant chemotherapy on RFS also differed by EGFR mutation status.