Surgery MCQs Q44

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SURGERY • ONCOLOGY

A patient with a diagnosed gastrointestinal malignancy is being followed up using a tumor marker to monitor recurrence and treatment response. The clinician orders carcinoembryonic antigen (CEA) levels.

In which malignancy is CEA most commonly used?

A Testicular tumor

B Colonic carcinoma

C Carcinoma of the ovary

D Pancreatic carcinoma

E Malignant melanoma

The correct answer is Colonic carcinoma.

Decoding the Stem

1

CLUE "CEA tumor marker"

TRANSLATION Most classically associated with colorectal cancer monitoring.

Detailed Explanation

✅ Correct Option (Colonic Carcinoma): Carcinoembryonic Antigen (CEA) is a glycoprotein involved in cell adhesion. While it is produced during fetal development and disappears after birth, it reappears in certain malignancies. It is most classically used as a tumor marker for colorectal carcinoma to monitor for recurrence and assess treatment response.

❌ Why other options are incorrect:

→ Testicular tumor: Markers include AFP (yolk sac component), β-hCG (choriocarcinoma/seminoma), and LDH.

→ Ovarian carcinoma: Primarily followed with CA-125.

→ Pancreatic carcinoma: Primarily followed with CA 19-9.

→ Malignant melanoma: No specific diagnostic serum tumor marker; LDH is used for prognosis.

🧠 High-Yield Pearls

✔ CEA: Colorectal cancer (Monitoring, not screening).

✔ CEA can be elevated in smokers: This reduces its specificity.

✔ AFP: Hepatocellular carcinoma & Yolk sac tumors.

Integrated Clinical Questions

1. Tumor marker for hepatocellular carcinoma?

→ Alpha-fetoprotein (AFP).

2. Tumor marker for prostate cancer?

→ Prostate-Specific Antigen (PSA).

3. Tumor marker for pancreatic cancer?

→ CA 19-9.

4. Tumor marker for ovarian cancer?

→ CA-125.

5. Limitation of CEA?

→ Low specificity; false positives occur in smokers, liver disease, and inflammatory bowel disease.

⚡ Exam Pearls

• • CEA = colon cancer (most tested association).
• • Not for screening → only used for follow-up and treatment monitoring.
• • Always match: Tumor ↔ marker for common exam MCQ sets.

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