Normal CEA Level in Adults
The normal CEA level is less than 5 ng/mL, though some evidence suggests that levels above 2.35 ng/mL may indicate worse prognosis in colon cancer patients. 1
Standard Reference Range
- The widely accepted upper limit of normal for CEA is 5 ng/mL in adults, as established by the American Society of Clinical Oncology 2, 3
- This threshold is used for both diagnostic and prognostic purposes in clinical practice 4
Refined Thresholds for Colon Cancer Patients
For patients with a history of colon cancer, more nuanced interpretation is warranted:
- Post-operative CEA >5 ng/mL suggests worse outcome and potential recurrence 1
- CEA >2.35 ng/mL may also indicate poorer prognosis, though the guideline text appears truncated at this value 1
- Recent research demonstrates that even CEA ≥2.1 ng/mL (within the traditional "normal" range) is an independent risk factor for worse disease-free survival in patients who underwent curative resection 5
Clinical Context Matters
Several non-malignant conditions can elevate CEA, making interpretation critical:
- Smoking history commonly elevates CEA levels 2, 4
- Inflammatory bowel disease, gastritis, peptic ulcer disease, and diverticulitis can raise CEA 2, 3, 4
- Liver diseases, COPD, diabetes, and other inflammatory states affect CEA levels 2, 3
- Benign biliary obstruction, especially with cholangitis or liver abscess, can significantly elevate CEA 2
Prognostic Significance in Colon Cancer
Preoperative CEA levels carry independent prognostic value:
- CEA ≥5 ng/mL preoperatively correlates with poorer prognosis regardless of tumor stage 1, 2, 3, 6
- Elevated preoperative CEA is an independent prognostic variable with a relative risk of recurrence of 3.74 7
- The prognostic impact is particularly significant in stage II disease 6
- CEA levels correlate with tumor stage, with highest values in stage IV disease 7
Monitoring Recommendations for Colon Cancer Survivors
For patients with stage II or III colon cancer after curative resection:
- Measure CEA every 3 months for at least 3 years after diagnosis 2, 3, 8
- Any elevation above baseline warrants confirmation with repeat testing 2
- Rising CEA strongly suggests disease progression even without radiographic confirmation 2
- CEA has 77% sensitivity and 98% specificity for detecting recurrence, with 100% sensitivity for liver metastases 7
Important Caveats
- CEA is not suitable for cancer screening in asymptomatic populations due to low sensitivity despite high specificity 2, 3
- CEA alone should never be used to diagnose cancer or initiate treatment without histologic confirmation 2
- During the first 4-6 weeks of chemotherapy, CEA may be transiently elevated and should be interpreted cautiously 2, 3
- Markedly elevated CEA (>25 ng/mL) is highly suggestive of metastatic disease, particularly hepatic metastases 4