Although medical science is advancing day by day, tumor is still the main cause of human death and people are still afraid of talking about cancer. Whether a tumor can be detected, diagnosed and treated early determines the prognosis of the tumor. Tumor markers provide the possibility for early detection of tumors, and tumor marker testing has been included in the medical checkup program. However, when patients are faced with the tumor marker list, they are still like reading a book in heaven and cannot figure out the reason. There are about 30 kinds of tumor markers, about ten of them are commonly used in clinical practice, which can detect most of the common human tumors and cancers. Although these tumor markers are non-specific, the combined test of multiple tumor markers can detect and diagnose tumors 3D5 years earlier than conventional examinations (X-ray, CT, MRI, ultrasound, cytopathology), and can detect early tumors without symptoms, which can provide valuable time for treatment. It can also detect early tumors without symptoms, which can gain valuable time for treatment. For example, AFP (alpha-fetoprotein) is the most commonly used indicator to detect liver cancer, and it can also monitor testicular tumors. However, it is important to note that AFP is non-specific. Non-specific means that a high test value is not necessarily a tumor. The value of AFP in healthy people is ≤25ug/L. However, if the test result is higher than this value, it does not mean that the dreaded liver cancer is present. This is because AFP levels can rise significantly in women during both menstruation and pregnancy, and having hepatitis disease can also cause AFP levels to rise briefly. Hepatocellular carcinoma can only be highly suspected if three consecutive test results are above 400ug/L. In addition, elevated AFP can also indicate liver metastasis of cancer, such as lung cancer, breast cancer, etc. metastasis to liver can cause elevated AFP. The most familiar tumor marker is CEA (carcinoembryonic antigen), which can indicate lung cancer, breast cancer, stomach cancer, colon/rectal cancer, pancreatic cancer, cervical cancer and thyroid cancer, and is a demon mirror for many tumors. However, there are many factors that can affect the elevation of carcinoembryonic antigen, such as long-term smoking and hepatitis, which can increase the level of carcinoembryonic antigen. It is important to note that because of the non-specific nature of tumor markers, combined monitoring is usually performed. For example, CA199 is a sensitive marker for pancreatic and bile duct cancers, but combined with AFP and CEA is beneficial in diagnosing gastrointestinal tumors. NSE is the preferred marker for small cell lung cancer, but is usually monitored in combination with Cyfra21-1 in order to improve the diagnostic rate. Even when you see that your test result is higher than the reference value, do not be blindly alarmed because: 1. Tumor markers, as qualitative and quantitative indicators, often require continuous observation to reflect the nature of human biosignals more objectively. Therefore, if the indicators are elevated in normal asymptomatic physical examination population, they should be reexamined after one month or several times, or do corresponding further targeted examinations in order to get objective results; 2. Patients who are highly suspected of tumor should find a specialist to confirm the diagnosis; 3. Some inflammatory diseases cause transient elevation of corresponding indicators and should be followed up.