Background: The epidemiology of epidermal growth factor receptor (EGFR) mutation in lung adenocarcinoma and its clinical impact are well-known. However, most studies have focused on advanced-stage inoperable cancer. Data on the frequency of EGFR mutation in surgically resected lung cancer are limited. Recent studies have shown a promising effect of Osimertinib in adjuvant settings. Hence, the need to estimate the target population in the real-world data. This study aimed to assess the occurrence of EGFR mutation in patients after radical surgical treatment of lung adenocarcinoma and explore its prognostic impact compared to EGFR negative group. Methods: This single-center retrospective analysis included the group of 732 consecutive Caucasian patients with histopathologically confirmed lung adenocarcinoma, evaluated for EGFR mutations expression, who underwent anatomical resection between January 2016, and December 2020. EGFR status was assessed by cobas EGFR mutation test v2. The frequency of EGFR mutations, disease-free survival (DFS) and overall survival (OS) in EGFR positive and EGFR negative groups were analyzed. Results: EGFR mutations were found in 65 surgical patients (8.9%) and did not differ from patients with advanced stages of lung adenocarcinoma (7.9%). EGFR mutations occurred more frequently in females than males, 48 out of 344 (14%) and 17 out of 388 (4.4%), respectively. Deletions within exon 19 and the L858R mutation in exon 21 constituted 49.2% and 24.6% of all mutations, respectively, while others comprised 26.2%. One case of L858R mutation coincided with T790M in exon 20 mutation. Detailed results divided by stages are presented in the Table. The occurrence of EGFR mutation had no significant influence on DFS and OS in patients after radical resection. Conclusions: The frequency of EGFR mutation in postoperative lung cancer was comparable to the occurrence in the general lung cancer population. EGFR mutation did not affect DFS and OS in patients after radical resection.

¹According to the 8^th edition of IASLC guidelines.