Today, I will help you understand tumor markers.

There are many types of tumor markers, each with different implications. I have summarized some key knowledge about tumor markers and will share them with you one by one in the coming days. Today, let’s start by discussing one type of tumor marker – carcinoembryonic antigen.

Carcinoembryonic antigen, abbreviated as CEA, is a glycoprotein complex first isolated from colon cancer and embryonic tissues by two Canadian researchers in 1965.

Carcinoembryonic antigen is synthesized in large quantities in the fetal digestive tract and some tissues during early development, resulting in high CEA levels in fetuses. After six months of gestation, CEA levels gradually decrease, and only trace amounts remain in the serum after birth. In healthy adults, CEA levels in the serum are very low, often undetectable. However, when cells become cancerous, CEA levels rise significantly.

This change may be related to alterations in oncogenes. When cells undergo malignant transformation, the expression of corresponding genes on chromosomes changes. The CEA gene, which is normally suppressed, becomes reactivated in cancer cells, leading to the production of carcinoembryonic antigen.

Carcinoembryonic antigen can be detected in various body fluids and excretions, including serum, cerebrospinal fluid, breast milk, gastric juice, pleural effusion, ascites, urine, and stool. Initially, CEA was regarded as a specific marker for early diagnosis of colon and rectal cancers. However, extensive clinical practice later revealed that elevated CEA levels are not only associated with gastrointestinal malignancies but are also observed in the serum of patients with breast cancer, lung cancer, and many other malignant tumors.

Thus, carcinoembryonic antigen is not a single marker indicating a specific type of tumor, but rather a broad-spectrum tumor marker. Clinically, it can be used to evaluate the diagnosis, treatment efficacy, and recurrence monitoring of many types of tumors.

Does an elevated carcinoembryonic antigen level definitely indicate malignant tumors?

No. Apart from malignant tumors, many other factors can lead to elevated carcinoembryonic antigen levels:

1. Inflammation. Inflammation in various parts of the body can cause an increase in carcinoembryonic antigen levels, such as chronic gastritis, hepatitis, pelvic inflammatory disease, cervicitis, vaginitis, etc.

2. Gastrointestinal diseases. Certain gastrointestinal conditions can also lead to an increase in carcinoembryonic antigen (CEA), such as intestinal obstruction, biliary obstruction, pancreatitis, cirrhosis, ulcerative colitis, and others.

3. Benign tumors. Benign tumors can also cause an elevation in CEA, such as gallbladder polyps, breast nodules, colon adenomas, and so on.

4. Smoking. Individuals who have smoked for an extended period and in large quantities may also have elevated CEA levels.

5. Elderly individuals. Many older adults may also show increased CEA levels, which may be associated with the frequent occurrence of chronic inflammation and benign lesions in the elderly.

What is the difference between benign and malignant causes of elevated CEA?

Since both malignant tumors and benign lesions can lead to an increase in CEA levels, how can we differentiate between the two?

We mainly look at the level of the value and its duration.

The increase in CEA caused by benign lesions is mostly mild and often transient, not lasting for a long time. For example, you might have elevated levels this month during a check-up, but they could return to normal by next month.

In contrast, the elevation of carcinoembryonic antigen caused by malignant tumors is mostly a doubling increase and often persists; if it is elevated in a test this month, it will likely still be elevated in the test next month.

Furthermore, the elevation of tumor markers caused by malignant tumors typically has another characteristic: multiple tumor markers are elevated. It is rare for a patient with a malignant tumor to have only a single elevated tumor marker; more commonly, many types of tumor markers are elevated simultaneously.

The Significance of Carcinoembryonic Antigen Testing

What is the significance of testing for carcinoembryonic antigen? The significance of carcinoembryonic antigen testing goes beyond just screening for malignant tumors; it also plays a crucial role during the treatment of cancer.

During the treatment process, measuring carcinoembryonic antigen allows us to understand tumor activity and evaluate treatment effectiveness through changes in its numerical values.

Furthermore, after the completion of treatment, we also conduct regular follow-up checks of carcinoembryonic antigen. Monitoring changes in its values helps determine whether the tumor has recurred or metastasized.

Therefore, for many cancer patients, carcinoembryonic antigen is a very important test item. Do not think, "My results have always been normal, so why does the doctor keep asking me to test it?" Consistent normal results are a good thing. If abnormalities appear, it’s time to take them seriously.

That’s all for today’s sharing. Next is the Q&A session—feel free to ask any related questions. #Cancer# #Health# #DailyMedicalScience#