A 59-year-old man complains of progressive weakness. He reports that his stools are very dark. Physical examination demonstrates fullness in the right lower quadrant. Laboratory studies show iron deficiency anemia, with a serum hemoglobin level of 7.4 g/dL. Stool specimens are positive for occult blood. Colonoscopy discloses an ulcerating lesion of the cecum. Which of the following serum tumor markers is most likely to be useful for following this patient after surgery?
A 59-year-old man complains of progressive weakness. He reports that his stools are very dark. Physical examination demonstrates fullness in the right lower quadrant. Laboratory studies show iron deficiency anemia, with a serum hemoglobin level of 7.4 g/dL. Stool specimens are positive for occult blood. Colonoscopy discloses an ulcerating lesion of the cecum. Which of the following serum tumor markers is most likely to be useful for following this patient after surgery?
💡 Explanation
**Core Concept**
Carcinoembryonic antigen (CEA) is a tumor marker associated with various types of cancers, particularly colorectal carcinoma. Elevated levels of CEA can be found in the serum of patients with colorectal cancer, and it is often used as a prognostic indicator for recurrence and metastasis.
**Why the Correct Answer is Right**
CEA is produced by colonic mucosa and is often elevated in patients with colorectal cancer, including those with ulcerating lesions of the cecum. After surgical resection, CEA levels can be used to monitor for recurrence or metastasis. A rising CEA level post-surgery may indicate residual or recurrent disease, while a stable or decreasing level suggests a favorable outcome. The use of CEA as a tumor marker is well established in clinical practice, and it is particularly useful for following patients with colorectal cancer.
**Why Each Wrong Option is Incorrect**
**Option A:** Alpha-fetoprotein (AFP) is a tumor marker associated with hepatocellular carcinoma, germ cell tumors, and certain other cancers, but it is not typically elevated in colorectal cancer. AFP levels may be elevated in patients with liver metastases from colorectal cancer, but it is not the most useful marker for following patients with colorectal cancer.
**Option C:** Chorionic gonadotropin (hCG) is a tumor marker associated with choriocarcinoma, germ cell tumors, and certain other cancers, but it is not typically elevated in colorectal cancer. hCG levels may be elevated in patients with certain types of cancers, but it is not the most useful marker for following patients with colorectal cancer.
**Option D:** Chromogranin is a precursor to several peptides, including chromogranin A, which is a tumor marker associated with neuroendocrine tumors. Chromogranin is not typically elevated in colorectal cancer, and it is not the most useful marker for following patients with colorectal cancer.
**Clinical Pearl / High-Yield Fact**
CEA levels can be elevated in patients with colorectal cancer, and a rising CEA level post-surgery may indicate residual or recurrent disease. However, it is essential to note that CEA levels can also be elevated in patients with other types of cancers, as well as in patients with benign conditions such as inflammatory bowel disease.
✓ Correct Answer: B. Carcinoembryonic antigen.
✓ Correct Answer: B. Carcinoembryonic antigen
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