When do you order Carcinoembryonic Antigen (CEA) and Alpha-Fetoprotein (AFP) in patients with suspected or confirmed cancer?

When to Order CEA and AFP in Cancer Patients

CEA and AFP should be ordered in specific clinical scenarios: CEA primarily for colorectal cancer monitoring after diagnosis (not for screening), and AFP for suspected hepatocellular carcinoma in cirrhotic patients. 1, 2

Carcinoembryonic Antigen (CEA) Guidelines

Appropriate Uses:

• Preoperative assessment in diagnosed colorectal cancer patients to assist with staging and surgical planning 1, 2
• Postoperative surveillance in stage II-III colorectal cancer patients 2:
  • Every 3 months for first 3 years
  • Every 6 months until 5 years postoperatively
• Monitoring response to therapy in metastatic colorectal cancer 2:
  • Measure at start of treatment
  • Every 1-3 months during active treatment

Not Recommended:

• Screening for colorectal cancer (insufficient sensitivity) 1, 2, 3
• Determining need for adjuvant therapy based solely on preoperative levels 1
• Initiating systemic therapy based solely on elevated CEA without radiographic confirmation 1, 2

Interpretation of CEA Results:

• Elevated CEA (>5 ng/mL) warrants further evaluation for metastatic disease 2
• Rising values should be confirmed by retesting 2
• Two consecutive elevated values can document progressive disease 1
• Non-cancer causes of elevated CEA include gastritis, peptic ulcer disease, diverticulitis, liver diseases, COPD, and inflammatory states 2

Alpha-Fetoprotein (AFP) Guidelines

Appropriate Uses:

• Diagnosis of hepatocellular carcinoma (HCC) in cirrhotic patients 1
  • Most useful when combined with imaging studies
  • AFP >200 ng/mL in a cirrhotic patient with a liver mass is highly suggestive of HCC

Diagnostic Algorithm for HCC:

1. For nodules >1 cm in cirrhotic patients:

   • Typical hallmark on dynamic CT/MRI (arterial hypervascularity with washout in portal/venous phase) can diagnose HCC 1
   • AFP may provide additional diagnostic information when imaging is inconclusive

2. For non-cirrhotic patients:

   • Pathologic diagnosis is recommended for all nodules 1

Clinical Pearls and Pitfalls

CEA:

• CEA is more sensitive for detecting liver metastases than locoregional or pulmonary metastases 3
• CEA may transiently rise during the first 4-6 weeks of chemotherapy without indicating disease progression 2
• CEA has a sensitivity of approximately 80% and specificity of 70% for detecting recurrent colorectal cancer 4
• CEA can provide a lead time of approximately 5 months before clinical recurrence is evident 4

AFP:

• AFP is highly specific for hepatocellular carcinoma when significantly elevated (>400 ng/mL) 5
• AFP is not elevated in cholangiocarcinoma, making it useful in differentiating primary liver cancer types 5
• Moderate AFP elevations (<100 ng/mL) can occur in metastatic liver disease and alcoholic liver disease 5

Combined Testing:

• Combined CEA, AFP, and CA19-9 testing may improve diagnostic accuracy for colorectal cancer compared to single marker testing, with CEA showing the highest diagnostic value (sensitivity 80.43%, specificity 75.00%) 6

Remember that tumor markers should always be interpreted in the clinical context and in conjunction with imaging studies and other diagnostic modalities.