In recent years, people have started to pay attention to medical checkups, but there are often people who are afraid of having tumor because of “tumor markers” such as increased CA 19-9 in their regular medical checkups. So what does the increase of CA 19-9 mean? How much is it related to tumor? The so-called tumor markers are substances produced by tumors themselves or by the body’s immune response to tumors, which are released into the blood and detected in the blood, thus indicating whether a tumor is present. However, tumor markers are specific and sensitive, that is, normal tissues or inflammation etc. may also cause elevated tumor markers, while tumors are sometimes not high. CA19-9 is a sugar chain antigen, which is present in fetal pancreatic, gallbladder, liver and intestinal tissues during embryonic period, but is very low in normal adult tissues. In adults, elevated CA19-9, especially persistently and significantly elevated, should be beware of pancreatic, biliary, gastrointestinal and gynecological tumors, among which, CA19-9 has the highest sensitivity and specificity for pancreatic tumors, both about 80%. The sensitivity of other tumors is about 40~50%. However, it should be noted that as people pay attention to medical checkups, more and more CA19-9 abnormalities are detected in medical checkups, while only a few percent of patients actually have malignant tumors. Therefore, it is important to pay attention to the increased CA19-9 found in physical examination, but there is no need to worry excessively. Because many benign diseases and inflammatory conditions, such as cholecystitis, bile duct stones, and even gastroenteritis may also have a transient increase in CA19-9. A transient increase is not something to be overly concerned about. Therefore, the first thing to look for is whether the increase is transient or persistent. Also, the magnitude of the elevation is important. A normal value of <37kU/L is significantly more sensitive and specific for diagnosing tumors if it is elevated twofold. If CA19-9 is persistently and substantially elevated, or even increasing, it has the highest sensitivity and specificity for pancreatic tumors, both being about 80%. In other words, 80% of people may have malignant tumor. It is necessary to do the corresponding examination. Diagnostic treatment process after CA19-9 increase 1. First of all, we should pay attention to whether there is any recent gastrointestinal inflammation, diarrhea, cholecystitis and other diseases, these benign diseases can also cause a transient increase in CA19-9. A young man in his twenties, who has been in good health, was found to have elevated CA19-9 to more than 150 in his routine physical examination, and a small cystic lesion of 0.5 cm on the pancreas was found in the CT examination. Outpatient inquiries revealed that he had been living irregularly for some time, often drinking outside, and his gastrointestinal tract was not good, with diarrhea. I told him to take rest and eat regularly. 1 week later, he was rechecked and the result of CA19-9 dropped to normal. There are also wards that often encounter patients with acute cholecystitis, CA19-9 will be very high, but after the inflammation of the gallbladder subsides, it quickly drops to normal. 2. Need to do abdominal CT examination: elevated CA19-9 is most related to the pancreas, biliary tract and gastrointestinal tract, but there are also tumors of the reproductive system. Therefore, a full abdominal CT is needed to fully examine the abdominal organs for tumors.3. If no tumor is found in the CT, CA19-9 should be rechecked within a short period of time (within 1 to 2 weeks), and if it drops to normal, it should be followed up and rechecked after 3 months.4. If CA19-9 does not drop and continues to rise, further gastroscopy and gynecologic ultrasound are needed. A female patient in the outpatient clinic has been found to have elevated CA19-9 for 4 years, and CA19-9 has been above 300, but she has done all the tests and no problems were found, so she has been followed up and rechecked once every 6 months. She was very worried. After arriving at the clinic, I reviewed her test data and no problems were found in the pancreas, gastrointestinal tract, or biliary tract, so I asked her to have a gynecologic ultrasound, which revealed an ovarian teratoma. After going to the gynecology department and having surgery, CA19-9 quickly dropped to normal.5 The vast majority of them will find out the cause, after all, CA19-9 continues to rise significantly and is rare in normal people. CA19-9 continues to rise significantly, even getting higher, 80% of people may have a malignant tumor, or a benign tumor has turned malignant. The actual CA19-9 is a very important part of the process.