Elevated tumor markers ≠ cancer diagnosis, you need to know this!

Cancer, as a disease that currently poses a serious threat to human health, has always received widespread attention. When people talk about cancer, their faces often change. Tumor markers, as important auxiliary indicators for diagnosing cancer, are a class of substances that are synthesized and released by tumor cells themselves, or that increase when the body reacts to tumor cells, mainly including proteins and sugars. The presence or quantitative changes of these markers can provide clues to the nature of the tumor.

However, an increase in tumor markers does not necessarily mean that you have cancer. Below, we will introduce you to several common tumor markers.

Alpha-fetoprotein (AFP) is a glycoprotein belonging to the albumin family. It is mainly synthesized by fetal liver cells and yolk sac. Its concentration in fetal blood circulation is high, and it gradually decreases after birth. It is basically replaced by albumin 2 to 3 months after birth, so its content in adult serum is extremely low. Alpha-fetoprotein has multiple physiological functions, including transport function, bidirectional regulation of growth regulatory factors, immunosuppression, T lymphocyte induction of apoptosis, etc. It is closely related to the occurrence and development of liver cancer and various tumors, and can be used as a positive detection indicator for various tumors.

Carcinoembryonic antigen (CEA) is mainly found in adult cancer tissues and fetal gastrointestinal tissues. It is a proteoglycan complex found in colon cancer, normal embryonic intestines, pancreas and liver. It is a broad-spectrum tumor marker, and if elevated, it should be diagnosed in combination with other markers. The CEA levels of patients with digestive tract tumors, lung cancer, breast cancer, and reproductive system tumors are elevated to varying degrees. However, the CEA levels of normal smokers, patients with hepatitis and cirrhosis, diabetics, and patients with colon polyps can also be elevated, so its specificity is not strong and its sensitivity is not high.

Cancer antigen 12-5 (CA12-5) is a glycoprotein derived from epithelial cells in the body cavity and expressed in normal tissues. In healthy people, blood CA12-5 is maintained at a low level. When suffering from epithelial ovarian cancer and endometrial cancer, the patient's serum CA12-5 level can be significantly increased. In addition, the CA12-5 content of patients with pancreatic cancer, lung cancer, and breast cancer can also be seen to increase. However, in early pregnancy, menstruation, pneumonia, heart failure, chronic hepatitis and other conditions, CA12-5 levels can also increase.

Cancer antigen 15-3 (CA15-3) is the hydrolyzed, detached or soluble form of MUC-1 protein. When cells become malignant, its abnormal expression and glycosylation changes are closely related to the pathogenesis of cancer formation and metastasis. Among patients with early breast cancer, the proportion of elevated CA15-3 is less than half; while the positive rate of patients with advanced breast cancer can rise to more than 80%. Therefore, CA15-3 is mainly used in clinical practice to judge the progression, metastasis and efficacy monitoring of breast cancer. However, benign breast diseases, ovarian diseases, gastroenteritis, liver diseases, etc. can also cause increased CA15-3 levels.

Cancer antigen 19-9 (CA19-9) is widely present in normal glandular epithelial cells with secretory function. The CA19-9 level will be increased in patients with pancreatic cancer, gallbladder cancer, bile duct cancer, liver cancer, gastric cancer, and colorectal cancer. Other benign diseases of the digestive tract such as pancreatitis, hepatitis, cirrhosis, pneumonia, and cholecystitis can also cause an increase in CA19-9 levels.

Cancer antigen 72-4 (CA72-4) is a polymorphic epithelial mucin associated with tumors. CA72-4 levels can be elevated in patients with gastric cancer, colon cancer, breast cancer, and lung cancer. It is the preferred marker for gastric cancer screening and has high specificity and sensitivity for gastric cancer. However, benign diseases of the digestive system, pancreatitis, gout, and benign gynecological diseases can also cause increased CA72-4 levels.

Neuron-specific enolase (NSE) is a type of enolase involved in the glycolysis pathway and is present in neural tissue and neuroendocrine tissue. It is a specific and sensitive detection indicator for judging the degree of brain damage and the prognosis of the disease. Small cell lung cancer is a tumor with neurosecretory properties, so NSE is one of the most sensitive and specific tumor markers for small cell lung cancer. In neuroblastoma and small cell carcinoma, the NSE measurement value is significantly increased. The NSE content can be seen to be increased in patients with medullary thyroid carcinoma, pheochromocytoma, melanoma, and pancreatic endocrine tumors. However, hemolysis, benign lung disease, hemorrhagic encephalopathy, ischemic encephalopathy, brain trauma, and intracranial infection can also cause an increase in NSE content.

In summary, when you see an increase in tumor markers, you don't need to panic too much. Because tumor markers are not unique to malignant tumors, abnormal increases in detection levels can also occur in many benign diseases, chronic diseases, and even in normal people. Although tumor markers are an important auxiliary means of diagnosing malignant tumors, you cannot simply assume that you have a malignant tumor based on one or several abnormal tumor markers. At present, the gold standard for cancer diagnosis is still pathological diagnosis. If cancer is really diagnosed, maintaining a good attitude is the key. Early detection, early diagnosis, and early treatment play a key role in the long-term survival of cancer patients. (Liu Fei, Medical Laboratory Department, Hechuan District People's Hospital, Chongqing)