Background:Hydrothorax,as one of the common complications of malignant tumors,still cannot be sensitively detected in clinical practice,thus requiring a sensitive,specific method for diagnosis.The aim of this study was to analyze the correlation between levels of vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) in patients with benign and malignant hydrothorax.Methods:The contents of VEGF in the pleural effusion and serum of the patients with malignant pleural effusion (n =35) and benign pleural effusion (n =30) were detected by double antibody sandwich enzyme linked immunosorbent assay.The gene copy number level of EGFR in pleural effusion was detected by fluorescence in situ hybridization (FISH).The points with the highest sensitivity and specificity were selected as the critical values to calculate the diagnostic value of the VEGF in pleural effusion and serum,and EGFR gene copy number in pleural effusion.Results:The contents of VEGF in pleural effusion and serum of patients with malignant hydrothorax were (384.91 ± 120.18),and (129.62 ± 46.35) ng/L,respectively,which were significantly higher than those of the patients with benign hydrothorax (207.97 ± 64.04),(63.49 ± 24.58) ng/L (P ＜ 0.01).The sensitivity and specificity of detecting VEGF in pleural effusion were 80.0％ and 96.7％ (the boundary value was 297.06 ng/L),respectively for diagnosing benign and malignant hydrothorax.The sensitivity and specificity of serum were 74.3％ and 96.7％,respectively (the boundary value was 99.21 ng/L) for diagnosing benign and malignant hydrothorax.The diagnostic efficiencies of EGFR and VEGF in hydrothorax were similar.There was a significant correlation between EGFR and VEGF in hydrothorax (P ＜ 0.01).Conclusions:VEGF and EGFR play important roles in the formation of pleural effusion.VEGF differed significantly in benign and malignant pleural effusions,which contributed to differential diagnosis results of benign and malignant pleural effusions.It is feasible to detect the gene copy number of the pleural effusion cell mass EGFR by FISH technique.Joint detection can improve the diagnostic sensitivity.