====== Carcinoembryonic antigen ======

A [[glycoprotein]], MW = 200,000. Normally present in fetal endodermal cells. Originally described in the early 1960s in the serum in patients with colorectal adenocarcinoma, it is now known to be elevated in many malignant and nonmalignant conditions (including cholecystitis, colitis, diverticulitis, hepatic involvement from any tumor, with 50–90% of terminal patients having elevation).

CSF [[CEA]]: levels>1ng/ml are reported with a leptomeningeal spread of lung Ca (89%),[[ breast cancer]] (60–67%), malignant melanoma (25–33%), and bladder Ca. May be normal even in CEA-secreting [[cerebral metastases]] if they don’t communicate with the subarachnoid space. Only [[carcinomatous meningitis]] from lung or breast cancer consistently elevates CSF CEA in the majority of patients.