What are the implications of elevated Carcinoembryonic Antigen (CEA) levels?

From the Guidelines

Elevated CEA levels require prompt evaluation and investigation, as they may indicate colorectal cancer or other malignancies, and regular monitoring is crucial for patients with a history of colorectal cancer. If you have an elevated CEA level, you should consult with your healthcare provider promptly for a comprehensive evaluation, including a detailed medical history, physical examination, and appropriate imaging studies such as CT scans of the chest, abdomen, and pelvis 1. For patients with a history of colorectal cancer, elevated CEA may suggest recurrence and warrants immediate attention. Additional testing may include colonoscopy, especially if you haven't had one recently or have never undergone screening. It's essential to understand that CEA is not specific enough for cancer screening in the general population and can be elevated in smokers, patients with inflammatory bowel disease, liver disease, or other non-cancerous conditions 1.

Some key points to consider:

• CEA levels should be monitored every 3 months for 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.
• Elevated CEA levels, if confirmed by retesting, warrant further evaluation for metastatic disease, but do not justify the institution of adjuvant therapy or systemic therapy for presumed metastatic disease 1.
• CEA is the marker of choice for monitoring metastatic colorectal cancer during systemic therapy, and should be measured at the start of treatment for metastatic disease and every 1-3 months during active treatment 1.
• Persistently rising values above baseline should prompt restaging, but suggest progressive disease even in the absence of corroborating radiographs 1.

It's crucial to note that the normal range for CEA is typically less than 3 ng/mL for non-smokers and less than 5 ng/mL for smokers, though reference ranges may vary between laboratories 1. Regular monitoring of CEA levels is often part of follow-up care for patients with certain cancers, particularly colorectal cancer, where trends in CEA values over time are more informative than single measurements 1.

From the Research

Elevated CEA Levels

Elevated carcinoembryonic antigen (CEA) levels can be an indicator of various conditions, including colorectal cancer. The following points summarize the key findings related to elevated CEA levels:

• Elevated CEA levels are associated with advanced or metastatic disease and poorer prognosis in colorectal cancer patients 2.
• Failure of CEA to return to normal postoperatively can be indicative of residual or recurrent disease 2.
• CEA measurement has an important role in the investigation, management, and follow-up of patients with colorectal cancer 2.
• The likelihood of recurrence of disease is directly proportional to the value of the raised CEA level 3.
• A PET-CECT scan is a valuable tool to detect recurrence in patients with rising CEA levels during follow-up of colorectal cancer, irrespective of the baseline CEA secretor status 3.

Surveillance Strategies

Different surveillance strategies can be employed to detect recurrence in patients with elevated CEA levels, including:

• PET scans, which have the highest sensitivity to detect recurrence 4.
• CT scans, which have a lower sensitivity compared to PET scans but are still effective in detecting recurrence 4.
• Circulating tumor DNA (CtDNA) positivity, which has the highest specificity to detect recurrence 4.
• Combinations of traditional cross-sectional/functional imaging and newer platforms such as CtDNA may result in optimized surveillance of patients following resection of colorectal cancer 4.

Colonoscopy Recommendation

Colonoscopy may be recommended for healthy individuals with elevated CEA levels, especially if accompanied by anemia, to evaluate the presence of colorectal malignancy 5.

• The incidence of colorectal cancer is higher in individuals with elevated CEA levels compared to those with normal CEA levels 5.
• Anemia is an independent predictive factor of colorectal cancer in healthy individuals with elevated CEA levels 5.

Serum CEA Levels in Different Diseases

Serum CEA levels can be increased in various types of cancers and noncancer diseases, including:

• Colorectal cancer, lung cancer, pancreatic cancer, and other types of cancer 6.
• Noncancer diseases such as lung fibrosis, uremia, chronic obstructive pulmonary disease, and Alzheimer's disease 6.
• Healthy individuals older than 65 years old may also have increased serum CEA levels 6.