[Correlation between the new lung adenocarcinoma classification and epidermal growth factor receptor mutation]

To evaluate the association of the histological subtype of lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutation.

A total of 94 patients with resected lung adenocarcinoma in the Department of Thoracic Surgery of China-Japan Friendship Hospital from January 2010 to December 2014 were enrolled in the study. All specimens were tested for EGFR mutation by a company. In the 94 patients, histological subtypes were classified according to the 2011 International Association for the Study of Lung Cancer and American Thoracic Society and European Respiratory Society classification. We compared the association with the histological subtype of lung adenocarcinoma with EGFR mutation frequency by the χ² test, with SPSS 20.0.

The 94 patients of surgically resected lung adenocarcinomas were included in this analysis, of whom, 47 were male and 47 female (male:female=1:1). The median age was 61 (range: 24-79) years, and 48 of the 94 patients were 60 years and above. Regarding the pathological staging, 34 patients were diagnosed as Stage I of the disease, 17 as Stage II,24 as Stage III, and 19 as Stage IV. Among the 51 patients with EGFR mutation, exon 19 mutation was 22, exon 20 mutation was 2, exon 21 mutation was 26, exon 20 and 21 mutation were 1, and the total EGFR mutation rate was 54.3% (51/94). The cases of EGFR gene mutation of acinar predominant lung adenocarcinoma, lepidic predominant lung adenocarcinoma, papillary predominant lung adenocarcinoma, solid predominant lung adenocarcinoma, micropapillary predominant lung adenocarcinoma and mucious adenocarcinoma were 24, 14, 5, 5, 3, and 0, respectively. The rate of EGFR gene mutation of acinar predominant lung adenocarcinoma was higher than that of non-acinar predominant lung adenocarcinom, but there was not statistically significant (66.7% vs. 46.6%, P=0.057). The rate of EGFR gene mutation of solid predominant lung adenocarcinoma was lower than that of non-solid predominant lung adenocarcinom (26.3% vs. 61.3%, P=0.005). The rate of EGFR gene mutation of mucious adenocarcinoma was lower than that of non-mucious adenocarcinom (0 vs. 57.3%, P=0.018).

There is heterogeneity of EGFR mutation in lung adenocarcinoma. The presence of lung adenocarcinoma with acinar indicates a higher EGFR mutation rate, while the solid and mucinous component indicates a lower EGFR mutation rate.