[Correlation between common driver gene variations and clinicopathological typing in lung adenocarcinoma]

Objective: To correlate the common driver gene variations in primary lung adenocarcinoma with their clinical characteristics and histopathological subtypes. Methods: There were 4 995 cases of primary lung adenocarcinoma diagnosed at Weifang People's Hospital of Shandong Province from January 2015 to December 2021 which were retrospectively analyzed. Among them 1 983 cases were evaluated for their histopathological subtype; 3 012 were analyzed for the correlation of their histopathological subtypes and corresponding driver gene variations, including invasive non-mucinous adenocarcinoma (INMA) and invasive mucinous adenocarcinoma (IMA), and morphologically, poorly-differentiated, moderately-differentiated and well-differentiated adenocarcinomas. Next-generation sequencing was used to detect variations in EGFR, KRAS, ALK, RET, ROS1, MET, HER2, or BRAF driver genes. Results: There were 2 384 males and 2 611 females. EGFR and ALK variations were more commonly found in female patients aged 60 years or older, with EGFR mutation rate in clinical stage Ⅰ (25.80%) significantly higher than in other stages (P<0.05). KRAS mutations were more commonly detected in male smokers aged 60 years or older, HER2 mutations were more commonly in patients younger than 60 years, and RET mutations were more commonly in non-smokers (all P<0.05). No correlation was found between ROS1, MET, and BRAF gene variations and their clinical characteristics (P>0.05). For the histopathological subtypes, among the 1 899 cases of acinar adenocarcinoma, EGFR mutation rate was the highest (67.30%) compared to the other genes. Exon 21 L858R and exon 19 del were the main mutation sites in IMA and INMA, with a higher mutation rate at exon 20 T790M (11.63%) in micropapillary adenocarcinoma. In IMA, KRAS had the highest overall mutation rate (43.80%), with statistically significant difference in mutation rates of exon 2 G12D and exon 2 G12V in acinar adenocarcinoma, solid, and IMA (P<0.05). KRAS mutation at various sites were higher in poorly differentiated groups compared to moderately- and well-differentiated groups (P<0.05). HER2 mutations were more commonly observed in acinar adenocarcinoma, papillary, and micropapillary adenocarcinoma of INMA. BRAF mutation was higher in micropapillary adenocarcinoma compared with other types (P<0.05). Conclusions: Variations in EGFR, ALK, KRAS, HER2, and RET in primary lung adenocarcinoma are associated with patients' age, smoking history, and clinical stage, and driver gene mutations vary among different histopathological subtypes. EGFR mutations are predominant in INMA, while KRAS mutations are predominant in IMA.