Carcinoembryonic antigen (CEA) is a substance produced by certain cells in the body. It functions as a “tumor marker,” a substance made by cancer cells or by normal cells in response to cancer. Measuring CEA levels in the blood can provide information useful in managing certain cancers.
Understanding Carcinoembryonic Antigen (CEA)
CEA is a glycoprotein normally produced in gastrointestinal tissue during fetal development. Production typically stops before birth, leading to very low levels in healthy adults. In adults, CEA is primarily expressed in tumor cells, especially adenocarcinomas like colon cancer. While associated with cancer, CEA is not unique to it. Elevated CEA levels can indicate various conditions, both cancerous and non-cancerous.
CEA Levels in Stage 2 Colon Cancer
For individuals with Stage 2 colon cancer, CEA testing serves a specific role. It is not used for diagnosis, but rather measured before surgery to establish a baseline level. This initial CEA level offers prognostic information, helping doctors understand the likely course of the disease. Higher pre-treatment CEA levels in Stage 2 colon cancer may indicate a slightly higher risk of recurrence. For example, patients with preoperative CEA levels above 5 ng/mL have shown lower disease-free survival compared to those below 5 ng/mL, providing a reference point for future monitoring.
Interpreting CEA Test Results
A “normal” CEA level for healthy, non-smoking adults is generally below 2.5 ng/mL or 3.0 ng/mL, though this varies between laboratories. For smokers, normal levels can be higher, typically up to 5 ng/mL. These ranges are general guidelines, and individual lab results may differ. Elevated CEA levels do not automatically confirm cancer and require further investigation. Many non-cancerous conditions can also cause CEA levels to rise, including inflammatory bowel disease, pancreatitis, liver diseases, peptic ulcers, diverticulitis, and chronic obstructive pulmonary disease (COPD). Smoking is also a common cause of elevated CEA. Therefore, an elevated CEA result is interpreted alongside a patient’s medical history, physical examination, and other diagnostic tests.
Ongoing Monitoring with CEA
After initial treatment for Stage 2 colon cancer, CEA levels are used for ongoing surveillance to detect potential recurrence. This monitoring typically involves periodic blood tests, often every 3 to 6 months for the first few years after surgery. The goal is to identify any significant rise in CEA, which could signal cancer has returned. If CEA levels, normalized after surgery, begin to rise steadily, it may prompt further investigations like CT scans or colonoscopies. While CEA monitoring can detect recurrence earlier, it is part of a broader surveillance strategy that includes other diagnostic tools, and a transient increase can sometimes occur at the start of chemotherapy without indicating disease progression.