CA125 is the most widely used ovarian epithelial tumor marker in the world. It is mainly used to determine how the disease progresses in women with some tumors and what the prognosis is after treatment, especially it is quite sensitive to monitor the efficacy of treatment. However, CA125 can also be increased in the presence of endometriosis, such as adenomyosis and chocolate cysts, and some inflammatory diseases can also cause an increase. So in the case of increased CA125 alone, we cannot necessarily say that we have a gynecological tumor, but CA125 is sensitive for the diagnosis of adenocarcinoma of the cervix, and endometrial cancer.