Tumor markers in blood, which are convenient, quick and relatively non-invasive to examine, are widely used in clinical practice. With the incidence of tumor diseases increasing year by year and the trend of younger age of onset, the early diagnosis and localization of malignant tumors are relatively difficult and the mortality rate is high, which seriously endangers human health. Tumor markers are also included in the physical examination program by more and more healthy people. Today, let’s learn what messages are released by CA125, a glyco-associated antigen (cancer antigen, tumor antigen), so that you can’t let your blood flow in vain! CA125 is a large transmembrane glycoprotein derived from epithelial cells of the corpora cavernosa (pericardium, pleura and peritoneum) and mullerian ducts (fallopian tubes, endometrium and endocervical lining).CA125 is mainly used in the detection of ovarian cancer and has a high positive rate for epithelial ovarian cancer. Its elevation is also seen in cervical cancer, endometrial cancer, fallopian tube cancer, etc. Other non-gynecologic malignancies such as pancreatic cancer, liver cancer, gastric cancer, lung cancer, breast cancer, gallbladder cancer, colon cancer, and malignant blood disorders may also show elevated serum CA125. Serum CA125 is the most widely studied biochemical method to screen for ovarian cancer. About 50% of patients with early-stage ovarian cancer and more than 80% of patients with advanced ovarian cancer have elevated serum CA125 values, and the degree of elevation correlates with tumor load and stage. A prospective study of asymptomatic postmenopausal women found that elevated CA125 concentrations (≥30 U/mL) were a strong predictor of risk for ovarian cancer, and continuous monitoring of CA125 levels is a more reliable screening method. However, false-positive results due to fluctuations in the menstrual cycle and benign gynecological lesions are more likely in premenopausal women. CA125 combined with transvaginal ultrasound can be used for early screening of ovarian cancer in women with a family history of ovarian cancer. Surveillance for ovarian cancer and CA125 Continuous monitoring of CA125 or other tumor markers (e.g., human epithelial protein 4) is recommended in the follow-up of patients with epithelial ovarian cancer, especially in patients who already have elevated CA125 levels at the initial diagnosis. Continuous monitoring of CA125 is useful in determining the efficacy of chemotherapy. Current guidelines are definitive on the use of CA125 for chemotherapy efficacy monitoring, but there is no consensus on how to define the optimal effective response to chemotherapy. It is recommended that CA125 levels be monitored during the first treatment, and its concentration before and after treatment is indicative of prognosis. Persistent elevation of its value indicates a poor prognosis. CA125 False Positive1 Analysis Approximately 1% of healthy women have elevated serum CA125 and it fluctuates with the menstrual cycle. Mean CA125 levels in the population vary with age, race and smoking status. CA125 is also elevated in a variety of benign conditions, including: peak ovulation, menstruation, early pregnancy; endometriosis, inflammatory pelvic disease, ovarian cysts; uterine fibroids, acute and chronic pancreatitis, benign gastrointestinal disease, renal failure, autoimmune disease, lung infection, chronic obstructive pulmonary disease; cirrhosis with or without ascites, heart failure, chronic active hepatitis; any cause of pleural effusion or peritoneal effusion. Serum glycoantigen 125 (CA125) is used in the diagnosis of ovarian cancer (plasma), to guide the prognosis of ovarian cancer (plasma), and is widely used in the monitoring and follow-up of the outcome of ovarian cancer (plasma)/breast cancer.