[Results of EGFR Mutations Detected in Pleural Effusion and Its 
Clinical Significance in 132 Patients with Advanced Non-small Cell Lung Cancer: 
A Retrospective Study in A Single Center].

backgroundThe lack of pathological quality control standard in detecting epidermal growth factor receptor (EGFR) gene mutation in malignant pleural effusion leads to confusion in the interpretation of detection results and the clinical use of EGFR-tyrosine kinase inhibitor (TKI). Therefore, it is very important to propose quality control standards and guide the detection of EGFR mutation in pleural effusion. The aim of this study is to retrospectively analyze the results of EGFR gene mutation in pleural effusion sediment section according to strict pathological quality control standards, and the therapeutic effect of EGFR-TKIs guided by this detection results.

methodsFrom January 2012 to June 2018, the clinical data of patients with pleural effusion collected from Department of Pathology of Peking Union Medical College Hospital were analyzed retrospectively. Among them, 132 patients with relatively complete clinical data and with EGFR gene mutation detection of paraffin-embedded pleural effusion sediment section according to the established quality control standard were included. According to the results of EGFR gene mutation, it was divided into positive group and negative group, and the efficacy of EGFR-TKIs in different groups was compared.

resultsAfter the centrifugation of pleural effusion, the sediment was embedded in paraffin, sectioned, and observed under the microscope after HE staining. If the number of tumor cells ≥100, it met the pathological quality control standard, and it could be used for subsequent EGFR gene mutation detection. EGFR gene mutations were detected in 72 (54.5%) of 132 patients. EGFR-TKIs were used in 69 of 72 mutation positive patients. Of 60 EGFR mutation negative patients, only 15 used EGFR-TKIs. In EGFR mutation positive group, the disease control rate (DCR) was 95.8%, and the median progression-free survival (PFS) was 11 months. In EGFR mutation negative group, the DCR was 0%, and the median PFS was 1 month. The DCR and PFS were significantly different between the two groups (P<0.05).

conclusionsAccording to the pathological quality control standards, the embedded section of pleural fluid sediment can be used to detect EGFR gene mutation, and the results can be used to guide the clinical use of EGFR-TKIs.