Ovarian cancer metastasizing to the lungs may cause elevated CA125. CA125 is carcinoembryonic antigen 125, a glycoprotein tumor-associated antigen. It is commonly used to screen patients for ovarian tumors, cervical cancer and other gynecologic tumors such as endometrial cancer. It plays an important role in the diagnosis of plasma ovarian cancer and epithelial ovarian cancer. Meanwhile, CA125 can also be used as an indicator for evaluating the treatment effect of ovarian cancer and other diseases. When the disease recurs or metastasizes, CA125 will often be elevated. Therefore, when ovarian cancer metastasizes to the lungs, elevated CA125 can generally occur. It is suggested that ovarian cancer patients should go to regular hospitals for regular follow-up, and if CA125 is elevated again, they need to make clear diagnosis under the guidance of specialists, and adjust the treatment plan if necessary, so as to avoid delaying the treatment.