Three published studies have investigated the diagnostic value of the pleural vascular endothelial growth factor, carcinoembryonic antigen (CEA), carbohydrate antigens (CA) 125, 15–3 and 19–9, and CYFRA 21–1 in MPE but have failed to identify a reliable tumor marker with both high sensitivity and high specificity. This evidence concerns the gene CEACAM5 and neoplasm.