8. A 65-year-old man presents to the emergency department after he had abnormall

Question

8. A 65-year-old man presents to the emergency department after he had abnormally tarry-colored stool on multiple occasions. He has had gastrointestinal discomfort and has felt increasingly tired during the past 2 months. Physical examination reveals a guaiac-positive stool. A subsequently colonoscopy identified a circumferential mass in the sigmoid colon. A biopsy was performed, which identified the mass as arn adenocarcinoma. CEA level was obtained as part of the presurgery workup. a. Is the CEA test useful as a screening test for colon carcinoma? b. What other conditions can result in elevated CEA levels? c. How is CEA used to monitor patients after surgery for colon cancer? 7

Explanation / Answer

CEA (Carcinoembryonic antigen)

CEA is a substance which found on the surface of some cells.It is a type of glycoprotein produced by cells of the gastrointestinal tract during embryonic development. It is very small amounts after birth. The level of CEA in the blood is thus relatively low unless certain disease including certain forms of cancer is present.

CEA is most frequently tested in blood.It can also be tested in body fluids and in biopsy tissue. The normal range for CEA in an adult non-smoker is<2.5 ng/ml and for a smoker <5.0 ng/ml

A.

CEA is a tumour marker, especially for cancers of the gastrointestinal tract.An elevated level of CEA represents progression or recurrence of cancer. But, CEA test by itself is not specific enough to substantiate a recurrence of cancer. Moreover, >20 ng/ ml before therapy may be associated with cancer which has already spread. The most frequent cancer which causes an increased CEA is cancer of colon and rectum. Also, it is not an effective screening test for occult cancer because early stage of tumours may not cause an abnormal finding.

B.

Elevated CEA level may also be due to:

C.

Patients whose CEA level was high prior to surgery (7 days before) and continued to rise postoperatively(after 7 days), the survival rate is poor and the recurrence rate is high.

so, surveillance of these patients with high postoperative serum Cea with an unknown cause should be extended, and these patients should be examined with sensitive diagnostic methods and should, potentially, be treated for recurrence at an earlier stage of the disease.

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