For progression-free survival, significant heterogeneities were observed for the prognostic significance of stage (I2 = 87.8%; P < 0.001), smoking status (I2 = 64.7%; P < 0.001), ECOG PS (I2 = 83.5%; P < 0.001), stage (I2 = 87.5%; P < 0.001), histology (I2 = 70.4%; P < 0.001) and serum VEGF (I2 = 80.7%; P = 0.001) in malignant patients with pleural effusion. The gene discussed is VEGFA; the disease is Pleural effusion.