This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'True about carcinoembryonic antigen (CEA)-a) Useful for screening of Ca. colonb) Gives confirmative evidence of Ca. colonc) Helpful for follow-up after resectiond) Levels decrease immediately after resection of tumore) Tumour size correlates with CEA level \nSelect and explain. \nA. ace, B. bde, C. cde, D. ade', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Carcinoembryonic antigen (CEA)\n\nCEA is produced by fetal gut, pancrease and liver.\nIt is a glycoprotein.\nIt can be used as a tumor marker in colorectal cancer (major use) and also in pancreatic, lung, breast, or ovarian carcinoma.\nIt is also increased in some non-neoplastic disorders, e.g. alcoholic cirrhosis, hepatitis, IBD (CD, UC), smoking, pancreatitis .\n\nUses of CEA in colon cancer\n\nScreening\nResponse to surgery after complete surgical resection, CEA should disappear in 6 weeks (not immediatly), Persistant beyond 6 week indicates residual tumor.\nHigher level suggests high tumor burden (size) → Prognostic value.\nFor follow up to see recurrence.\n\n\nCEA assays lack both specificity and sensitivity → can not be used to confirm the diagnosis.', 'role': 'assistant'}]