CA125, which stands for CancerAntigen 125, is one of the most commonly used gynecologic tumor markers. It is a glycoprotein first detected inside the epithelial cells of ovarian cancer. Usually, the normal value is below 35miu/ml. In many gynecological diseases or medical checkups, this test will be performed, but what does an increase mean? First of all, it is certain that CA125 is increased in many gynecological diseases, such as endometriosis, myometriosis, pelvic infection, tuberculosis, ascites, hepatitis, liver cirrhosis, benign and malignant ovarian tumors, etc. The increase of CA125 is often related to the severity of the disease, for example, the severity of endometriosis is related to CA125, and the indicator increases when the disease is severe and decreases when it is in remission. For example, the severity of endometriosis is related to CA125, which increases when the disease is severe and decreases when it is in remission. In benign diseases, the increase in CA125 is usually not too high, below 200 miu/ml, but in isolated cases, CA125 in inflammatory diseases can reach levels in the thousands. CA125 is a very sensitive indicator for ovarian cancer and a heavy elevation of CA125 is usually seen and correlates with the size and stage of the tumor. After tumor treatment, the indicator decreases and after recurrence, it increases, therefore CA125 is also commonly used for identification and recurrence monitoring of ovarian cancer. For elevated CA125 index, it is usually necessary to perform necessary screening. Usually, internal examination by gynecologist is a very necessary examination to understand whether there is endometriosis or inflammation. For substantial masses, surgery is usually required to obtain a definitive pathological diagnosis. Recently, the combination of CA125 and another tumor marker, HE4, has been used to identify benign and malignant masses that are difficult to identify. In the past, we used to use the Chinese marker of carcinoembryonic antigen 125 to note CA125 in hospitals, but recently, many hospitals started to use “glycogen protein 125” to replace the original text, such a change, in fact, is also to reduce the worry of many patients who got the test sheet, which is a good method. In conclusion, an increase in CA125 does not mean cancer, and many benign diseases may also show an increase in CA125, which needs further evaluation by doctors.