[Relationship between EGFR Mutations and Pathological Classification and 
Specimen of Lung Adenocarcinoma].

backgroundWith the development of genetic mutations and targeted drugs, accurate therapy of lung adenocarcinoma attracts much more attention, and more research is focued on epidermal growth factor receptor (EGFR). It is unclear whether the result of EGFR mutation and pathology type is consistent with different specimens. In our study, by comparing the relationship between EGFR mutations and pathological classification of lung adenocarcinoma in surgical resection of specimen and biopsy specimen, to discuss the relationship between EGFR mutations and pathological classification of and the influence of specimen type on EGFR gene detection.

methodsA total of 163 cases of surgical resection of sample of lung adenocarcinoma (pulmonary resection and pulmonary lobectomy) and 173 cases of biopsy specimen [mucosa biopsy, needle biopsy of lung, and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)] were performed by gene sequencing method and amplification refractory mutation system (ARMS) and the majority of the type was confirmed (lepidic, acinar, papillary, micropapillary, solid) according to the classification of lung adenocarcinoma in 2015 World Health Organization (WHO). The statistics was used in surgical and biopsy sample respectively.

resultsThe gene mutation of EGFR in surgical and biopsy sample of lung adenocarcinoma was 62.58% (102/163) and 65.9% (114/173) respectively, and no significant difference was found (P>0.05). The mutation of EGFR in female was predominant both of the two groups (P<0.05). The mutation rate of EGFR over the age of 60 was significantly lower than that below 60 in surgical specimen, while it was not related to age in biopsy sample. The constituent ratio of pathology type was different in the two groups (χ2=8.04, P<0.05). Among 102 cases of lung adenocarcinoma in surgical specimen, the acinar took up the highest proportion (54.9%), followed by the lepidic (23.53%) and the papillary (17.65%). The solid adenocarcinoma accounted for the minimal percentage (3.9%). The mutation of 19 and 21 exon alone was most common. The mutation rate of 21 exon in the lepidic was higher than that in the acinar and papillary (P<0.05), but the mutation rate of 19 exon in the papillary was higher than that in the lepidic (P<0.05). There was no significant difference of 19 and 21 exon in the acinar and papillary. Among 114 cases of lung adenocarcinoma in the biopsy specimen, the most percentage was the acinar (48.25%), the lepidic was secondly, and the papillary, micropapillary and solid adenocarcinoma was the minimal. The exon mutation of 19 and 21 exon alone was most common, while no obvious difference of 19 and 21 exon was found in different pathology classifications (P>0.05).

conclusionsThe mutation rate of EGFR of lung adenocarcinoma in surgical resected specimen and biopsy specimen was not found difference, which was related to sex, and the female was predominant. The mutation rate of surgical specimen was higher in the young, while that of biopsy specimen was not related to the age. Apparent difference of the pathology type proportion was found in the two groups. The mutation of 19 and 21 exon alone was most common. The mutation of EGFR in surgical specimens was related to pathology types. The percentage of the lepidic adenocarcinoma was highest in the mutation of 21 exon alone. Among the mutation of 19 exon alone, the papillary was predominant. There was no obvious relationship between the mutation of 19 and 21 exon alone and pathology type in biopsy sample.