Combined use of ascitic tumor makers and ADA (ascitic ADA < 22.5 IU/L or ascitic CEA > 3.65 ng/mL or CA15-3 > 42.70 U/mL or CA19-9 > 25.10 U/mL) performed high sensitivity (99.06%) and accuracy (94.08%) for the diagnosis of peritoneal carcinomatosis. The gene discussed is CEACAM5; the disease is neoplasm.