What does an elevated carcinoembryonic antigen (CEA) level indicate in a patient with a history of cancer?

What Carcinoembryonic Antigen (CEA) Tells You

Carcinoembryonic antigen (CEA) is a tumor marker that provides prognostic information and monitors disease activity in patients with established cancer—particularly colorectal cancer—but it should never be used for cancer screening or diagnosis due to its poor sensitivity and specificity. 1, 2

Primary Clinical Uses of CEA

In Colorectal Cancer (Most Important Application)

Preoperative Assessment:

• Order CEA preoperatively if it assists in staging and surgical planning 1
• Elevated preoperative CEA (≥5 ng/mL) correlates with poorer prognosis regardless of tumor stage 3, 4
• Establishes a baseline for postoperative surveillance 2

Postoperative Surveillance:

• Measure CEA every 3 months for at least 3 years in patients with stage II or III disease who are candidates for surgery or chemotherapy 1
• An elevated CEA confirmed by retesting warrants further evaluation for metastatic disease with imaging studies 3
• CEA alone does not justify initiating systemic therapy without radiographic or pathologic confirmation 1, 3
• CEA is the most cost-effective test for detecting potentially resectable metastases 1

Monitoring Metastatic Disease:

• CEA is the marker of choice for monitoring response to systemic therapy in metastatic colorectal cancer 1
• Measure at treatment initiation and every 1-3 months during active therapy 1, 2
• Persistently rising values above baseline suggest progressive disease even without radiographic confirmation 1, 3
• Critical caveat: Interpret rising CEA cautiously during the first 4-6 weeks of new therapy, especially with oxaliplatin, as spurious early rises may occur 1, 3

In Other Cancers

Breast Cancer:

• CEA is elevated in 50-60% of patients with metastatic breast cancer 3
• Can be used for monitoring metastatic disease during active therapy in conjunction with imaging 3
• Not recommended for screening, diagnosis, staging, or routine surveillance 2

Other Malignancies:

• Elevated in pancreatic cancer, lung adenocarcinoma (73.7% positive), medullary thyroid carcinoma (96.3%), and various gastrointestinal adenocarcinomas 5
• Approximately 30% of cholangiocarcinoma patients have elevated CEA 3

What CEA Does NOT Tell You

CEA is explicitly NOT recommended for:

• Cancer screening in asymptomatic populations 1, 2, 4
• Diagnosing cancer (only 50-60% of patients with metastatic colorectal cancer have elevated CEA) 2
• Determining whether to administer adjuvant therapy 1

Critical Confounding Factors

Non-malignant conditions that elevate CEA include: 2, 3, 6

• Gastrointestinal: gastritis, peptic ulcer disease, diverticulitis, inflammatory bowel disease
• Hepatobiliary: liver disease, benign biliary obstruction (especially with cholangitis or liver abscess)
• Pulmonary: COPD
• Metabolic: diabetes
• Other inflammatory states
• Smoking history 6

Age increases baseline CEA levels 2

Interpreting CEA Levels

Threshold values:

• Normal: <2.5-5 ng/mL (5 ng/mL is more realistic clinically) 1, 6
• Markedly elevated: >25 ng/mL strongly suggests metastatic cancer, particularly hepatic metastasis 6

Diagnostic accuracy depends on initial CEA level:

• Patients with elevated preoperative CEA are more likely to have elevated CEA at recurrence (59.4% vs. 23.4% in those with normal initial CEA) 7
• Overall sensitivity for detecting recurrence is only 33% 7
• Elevated CEA at recurrence is associated with worse overall survival 7

Clinical Algorithm for Elevated CEA

When CEA is elevated:

1. Confirm with repeat testing 3
2. Perform CT chest, abdomen, and pelvis to identify metastatic sites 3
3. For colorectal cancer, focus on common metastatic sites (liver, lungs, peritoneum) 3
4. Consider non-malignant causes before extensive workup 3
5. Do not initiate therapy based on CEA elevation alone without imaging or pathologic confirmation 1, 3