Carcinoembryonic Antigen (CEA) details

CEA is a tumor marker used mainly to monitor treatment response and watch for recurrence in colorectal cancer, and sometimes other cancers including certain lung, breast, and gastrointestinal cancers. It isn't accurate enough to screen for cancer in people without a diagnosis, since it can be normal even with cancer present, and can also be mildly elevated by smoking and various non-cancerous conditions like inflammatory bowel disease, liver disease, or pancreatitis. Its main clinical value is tracking levels over time in someone with a known cancer diagnosis — a rising trend after treatment can be an early signal of recurrence, sometimes appearing before it's visible on imaging.