“Does a high tumor marker mean cancer?” This is probably a common confusion of many patients when they are faced with various tumor marker labs. So today I will discuss this question with you in depth. 1. What are tumor markers? Once you see the words “tumor marker”, many patients may naturally think that it must be something that will appear only when they have cancer, but when asked about the exact meaning, probably most of them are unable to talk about it. In fact, from the definition, tumor marker is a kind of substance with specificity produced in the process of tumor cell production, differentiation and metabolism, which can be genes, proteins or compounds. Tumor markers have certain specificity, just like a person who has basketball, soccer and skateboard in his house, we would think that he must be a sportsman; if his house is full of Lin Yutang, Xu Zhimo and Shakespeare, we can infer that he is probably a literature lover. Tumor markers are such characteristics of a tumor lover. But the fact is that people with a wide range of books may not love reading, people who wear sportswear every day may not be physically fit, and similarly high tumor markers cannot accurately predict the existence of tumor every time, which leads us to the next question. 2. How exactly should we evaluate tumor marker results? To comment on tumor marker results, we first need to figure out how its normal value is determined? Similar to many other statistical indicators, the normal range of tumor markers does not include all normal people, rather, it generally covers only 95% of the normal population, so a higher normal value does not necessarily mean abnormal. This is like a class of 100 people, the shortest is 1.5m and the tallest is 1.9m, but 95 of them fall between 1.6 and 1.8m, so we would say that the more common normal height of children in this class is between 1.6 and 1.8m, but 1.5, 1.9m is not abnormal, just uncommon. 3. Even so, is the tumor marker index we get necessarily accurate for tumor prediction? Actually, this is not certain. Generally, when seeing tumor marker results, clinicians will also think of two indicators that are also tested —- sensitivity and specificity. Let’s take an example, a tumor marker has 90% sensitivity and 80% specificity for a certain tumor. This translates to 9 out of 10 tumor patients will have a positive tumor marker; 8 out of 10 non-tumor patients will have a negative test result. In other words, the better the specificity, the stronger the specificity of the marker for a particular tumor, and the higher the sensitivity, the better the detection rate of the marker for a particular tumor. 4.What are the effects of tumor marker detection? At present, there is no test with 100% sensitivity and specificity. We often just choose the markers that are more compromised between the two and are more satisfactory for clinical use. Therefore, there is a possibility of false positives when patients are tested. For example, AFP, a marker for liver cancer, can be elevated in patients with hepatitis B and cirrhosis; HCG can be used to predict ovarian gonadotropic tumors, but it can be elevated in pregnancy, etc. In fact, besides the above factors of markers themselves, there are also many in vitro and in vivo conditions that can affect the detection of markers, such as hemolysis of specimens, contamination, and treatment can cause effects. In conclusion, it can be said that elevated tumor markers are not the verdict of cancer, but more like a reminder. When you see abnormal markers, you should not be alarmed and dizzy, nor should you be negligent and ignore it. I think it is more appropriate to look at it rationally and pay high attention to it, and then you should listen to the advice of the specialist and consider it from multiple aspects in order to get a clearer conclusion.