CEA surveillance after colorectal cancer surgery

What it measures. Carcinoembryonic antigen (CEA, the protein CEACAM5) is made by fetal gut and by most colorectal adenocarcinomas; it is also raised in smokers, liver disease, lung and other cancers. Before surgery a high level is a poor prognostic sign and a baseline; after complete resection it should return to normal within weeks. In surveillance a sustained rise, confirmed on repeat, is the trigger for imaging.

Evidence and guidelines. The British FACS trial (JAMA 2014) randomised 1,202 patients after curative surgery to CEA every three months, CT every six to twelve months, both, or minimal follow-up. Any intensive strategy roughly trebled the proportion of recurrences treated with curative intent (from about 2 per cent to 6 to 8 per cent of patients), but at eight years there was no difference in cancer-specific or overall mortality, and a Danish trial (COLOFOL) of more versus less intensive imaging likewise found no survival difference. Guidelines from ASCO, ESMO and NICE nonetheless recommend CEA every three to six months for three years then six-monthly to five years, with CT at intervals, because the finding of resectable recurrence is meaningful to patients even if the population-level survival gain is small or absent.

What changes and where it is going. A confirmed CEA rise leads to CT of the chest, abdomen and pelvis, sometimes PET, and colonoscopy, aiming to find liver or lung metastases that can be resected or ablated. A stable normal CEA supports continuing routine follow-up without extra scans. About a third of recurrences never raise CEA, so it cannot replace imaging. Circulating tumour DNA testing after surgery, which detects residual disease months before CEA or CT and is being tested to guide adjuvant chemotherapy, is the likely successor and is already offered by several laboratories. The CEA test itself costs a few pounds.