From the Guidelines
CEA is primarily a marker of colorectal cancer, though it can also be elevated in other cancers and some non-cancerous conditions. It's a glycoprotein normally produced during fetal development that should be present only in very low levels in healthy adults. CEA is most commonly used to monitor colorectal cancer treatment response and detect recurrence after treatment. Elevated CEA levels may indicate cancer progression or recurrence, while decreasing levels often suggest effective treatment. However, CEA is not specific enough for cancer screening in the general population due to its elevation in other conditions like inflammatory bowel disease, pancreatitis, liver disease, and smoking. The normal range for CEA in healthy non-smokers is typically less than 3 ng/mL, while smokers may have slightly higher levels up to 5 ng/mL. Regular CEA testing is most valuable for patients already diagnosed with CEA-producing cancers to track their disease status over time, as supported by the 2020 ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of localized colon cancer 1.
Some key points to consider when using CEA as a marker include:
- CEA is not recommended for use as a screening test for colorectal cancer due to its low sensitivity and specificity 1
- Preoperative CEA testing may be useful in staging and surgical treatment planning, and elevated preoperative CEA levels may correlate with poorer prognosis 1
- Postoperative serum CEA testing should be performed every 3 months in patients with stage II or III disease for at least 3 years after diagnosis, if the patient is a candidate for surgery or systemic therapy 1
- CEA is the marker of choice for monitoring metastatic colorectal cancer during systemic therapy, and should be measured at the start of treatment and every 1-3 months during active treatment 1
Overall, CEA is a valuable tool in the management of colorectal cancer, but its use should be interpreted in the context of other clinical and diagnostic information.
From the Research
CEA as a Marker
- CEA is a recommended prognostic marker in Colorectal Cancer (CRC) for tumor diagnosis and monitoring response to therapy 2
- High CEA levels are specifically associated with CRC progression and increased levels of the marker are expected to fall following surgical treatment 2
- CEA is also elevated in other types of cancers, such as lung cancer, pancreatic cancer, and rectum cancer, as well as in noncancer diseases like lung fibrosis, uremia, and chronic obstructive pulmonary disease 3
- CEA levels can serve as an indicator of successful or incomplete resection, and are useful in monitoring the effect of chemotherapy or radiotherapy 4
Clinical Applications of CEA
- CEA measurement has an important role in the investigation, management, and follow-up of patients with colorectal cancer 5
- CEA can be used as an adjunct to clinical staging methods in known cancer patients, but it is neither sensitive nor specific enough to be used in routine screening for possible malignancy in an asymptomatic population 4
- CEA has been explored as a target for cancer therapy and diagnosis approaches, including drug delivery systems, photodynamic therapy, radioimmunotherapy, cancer imaging, and nanotechnological devices 2
Prognostic Value of CEA
- Higher preoperative CEA levels are associated with advanced or metastatic disease and thus poorer prognosis 5
- Failure of CEA to return to normal postoperatively is indicative of residual or recurrent disease 5
- Measuring CEA preoperatively in CRC patients can be useful as a prognostic factor, especially when combined with other tumor markers like CA19-9 6