In recent years, the prevalence of malignant tumors has been increasing, and people are scared of talking about “cancer”. Therefore, we all hope that we can screen, diagnose or exclude malignant tumors at an early stage by checking tumor markers during the annual physical examination. As the name suggests, tumor markers are some indicators closely related to cancer, which are a kind of biochemical substances used to reflect malignant tumors, and their values are related to tumors. However, can the value of tumor markers really “hit the nail on the head”? Tumor markers also have “false positives” Ideally, the sensitivity and specificity of tumor markers should be 100%, and once increased, the diagnosis of malignant tumors can be confirmed. But in fact, tumor markers increase in addition to the occurrence of malignant tumors, some parts of the inflammation, intestinal polyps, inflammatory hyperplasia, skin diseases such as psoriasis, bile stasis, liver and kidney dysfunction, etc., can lead to a small increase in some of the tumor markers, that is, the “false-positive” performance. Therefore, it is not possible to diagnose malignant tumors solely on the basis of a single value. Physical examiners can go to oncology hospitals if their tumor markers are elevated. Doctors will first make a comprehensive analysis of the normal value range, the magnitude of increase, personal symptoms and the characteristics of the tumor marker, and then do ultrasound, CT, endoscopy, PET/CT and other tests if necessary. On the other hand, the fact that all tumor markers are normal does not mean that the possibility of cancer can be completely excluded, because its sensitivity has not reached 100% and there are many factors of “missed detection”. Many factors affecting tumor markers Tumor marker results are affected by many factors, such as diet, medication, specimen collection and storage. For example, pregnancy can cause the elevation of alpha-fetoprotein, glucose antigen and human chorionic gonadotropin; after prostate puncture and proctoscopy, the serum prostate-specific antigen can be elevated; and anti-androgen treatment of prostate cancer can inhibit the production of PSA, which can lead to false-negative results of PSA; abnormalities of the liver and kidney function and poor biliary excretion, bile stasis, and so on, can cause the tumor markers, such as carcinoembryonic antigen, alkaline phosphatase, gamma-glutamyl transpeptidase, γ-glutaminyl transpeptidase and γ-glutaminyl transferase, etc., which can cause the tumor markers. glutamyl transpeptidase, cytokines, etc.; if several needles are inserted before blood is drawn, it may lead to hemolysis of the specimen, which may lead to the elevation of squamous cell carcinoma antigen and lactate dehydrogenase; alcohol consumption will cause the elevation of GGT. Broad-spectrum tumor markers AFP, CEA, ferritin, etc. It is clinically confirmed that some tumor markers can be used for early screening. It is recommended that those who are engaged in high-pollution work and those who are entering high-risk age should be examined once a year, and those who have a family history of tumors should cross over to physical examination in advance. In the normal physical examination blood test, generally men check AFP, CEA, PSA, and women check AFP, CEA, CA125, HE4. If there is a family history of tumor or clinical symptoms, other tumor markers can be added accordingly. As the sensitivity and specificity of the existing tumor markers are not very high, they are usually used in the auxiliary diagnosis, differential diagnosis, efficacy monitoring and prognosis judgment of tumors, and it is recommended to combine them with other related indicators to improve the positive detection rate. Why tumor markers are high and low after surgery? The most effective application of tumor markers is to judge the efficacy of malignant tumors, monitor and indicate recurrence and metastasis. If the tumor markers are elevated before surgery and fall to normal after surgery, it often indicates that the surgical treatment is successful, but still need to follow up and continue to monitor its dynamic changes. If tumor markers do not decrease or even increase significantly after cancer treatment, it is necessary to consider whether the treatment plan is effective and whether the plan should be adjusted to achieve better efficacy. If the tumor markers return to normal for a period of time after surgery and become elevated again, it may suggest recurrence or metastasis of the tumor. Generally speaking, tumor marker abnormalities are manifested earlier than imaging tests, so recurrence or metastasis can be detected earlier to guide the clinic to carry out treatment as early as possible to prolong the survival period.