Carcinoembryonic antigen (CEA) is a tumour marker used in monitoring colorectal carcinoma. Which statement about CEA is MOST accurate?

• A CEA is diagnostic for colorectal carcinoma when elevated above 5 ng/mL
• B CEA elevation is specific to colorectal cancer and is not seen in other gastrointestinal cancers
• C A preoperative CEA above 2.5 ng/mL contraindicates surgical resection
• D CEA is most useful for monitoring response to therapy and detecting recurrence after curative resection ✓

Explanation

CEA lacks specificity for diagnosis — it can be elevated in benign conditions (smoking, IBD, cirrhosis) and non-colorectal cancers (gastric, pancreatic, breast, lung). Its primary clinical utility is postoperative surveillance: a rising CEA after curative resection is the earliest indicator of recurrence, prompting imaging workup. Preoperative CEA elevation is a prognostic marker (elevated > 5 ng/mL indicates advanced stage) but does not contraindicate surgery.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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