Carcinoembryonic antigen (CEA) is primarily a marker for which kind of cancer?

• A. Breast cancer
• B. Colorectal cancer
• C. Low-grade glioma
• D. Lung cancer

Answer: (B)

Carcinoembryonic antigen (CEA) is primarily associated with colorectal cancer. This glycoprotein is often utilized as a tumor marker, particularly in the diagnosis and monitoring of malignancies affecting the colon. Elevated levels of CEA in the serum can indicate the presence of colorectal cancer and are frequently measured to assess treatment response or detect recurrences after therapy. Although CEA may also be elevated in other types of cancer and conditions, its most significant clinical utility and association remain with colorectal cancer.

In contrast, options such as breast cancer, low-grade glioma, and lung cancer are not primarily monitored through CEA levels, as they more commonly utilize specific markers or imaging studies for diagnosis and follow-up. For instance, breast cancer often involves markers such as CA 15-3 or HER2, while lung cancer is typically assessed using markers like cytokeratin fragments or neuron-specific enolase (NSE). Therefore, CEA’s critical role is predominantly in relation to colorectal cancer, making it the correct answer.