CA125 is a glycoprotein that can be bound by the monoclonal antibody OC125, which was detected from epithelial ovarian cancer antigens in 1983. 95% of healthy adult women have CA125 levels ≤35 U/ml. CA125 is not only a specific marker for ovarian cancer, but also for other malignancies, such as endometrial, cervical, pancreatic, intestinal, breast and lung cancers. CA125 levels are also elevated in patients with other malignancies, such as endometrial, cervical, pancreatic, bowel, breast and lung cancers. If a physical examination reveals that the serum CA125 level is twice as high as the baseline level, it is necessary to go to the hospital for medical examination, which mainly includes abdominal and pelvic ultrasound, vaginal ultrasound and CT examination if necessary. However, elevated CA125 does not necessarily mean that you have ovarian cancer or other malignant tumors. It can also appear abnormally elevated in some benign diseases, such as endometriosis, pelvic inflammatory disease, ovarian cysts, etc. In addition, CA125 may also be elevated during the first 3 months of early pregnancy. Therefore, healthy people with mildly elevated CA125 should not be too nervous, as long as no malignant tumor is found through comprehensive examination, it can be safely excluded. Moreover, in the professional medical field of gynecologic tumor, CA125 test is not recommended as a routine screening tool for ovarian cancer diagnosis, and even elevated CA125 alone in high-risk groups cannot confirm the diagnosis of ovarian cancer or other malignant tumors. CA125 for ovarian cancer patients Not all ovarian cancer patients will have elevated CA125. For early stage patients (stage I and II), the CA125 positivity rate is about 50%- 60%. CA125 is more important for monitoring prognosis than for diagnosis. Most patients with early-stage ovarian cancer can have CA125 reduced to within normal level after surgery and postoperative chemotherapy; if CA125 does not decrease to normal within 3 months after starting treatment or decreases <80%, this group of patients often has a poor prognosis. Those who continue to be above the normal level after surgery or chemotherapy and do not see a decreasing trend often suggest the existence of microscopic lesions or recurrence. For patients with normal CA125 after treatment, there is no need to be overly nervous if CA125 is elevated again during monitoring, because elevated CA125 does not necessarily mean that the tumor has recurred. The time between CA125 elevation and clinical recurrence (which must be confirmed by ultrasound or CT) is about 2-6 months, and for patients who have previously received chemotherapy, the timing of receiving chemotherapy again is not uniform. There is no uniform opinion on the timing of receiving chemotherapy again for patients who have previously received chemotherapy. The CA125 test is subject to error due to three factors: the test specimen, the time of the test and the test instrument. For those with mild elevation, continuous monitoring (once a month) should be performed to determine if the elevation is continuous, then you should be more alert.