CA125, also known as glycoantigen 125, is a relatively common tumor marker. This marker may be more elevated in ovarian cancer in women, and in other germ cell tumors, such as teratoma. In other germ cell tumors, such as teratoma, CA125 is more elevated in malignant teratoma, but it is not definite, and there are some indicators that are not elevated or are in the normal range. In some benign teratomas, this indicator is usually normal. Generally, CA125 can be used as a follow-up indicator for ovarian cancer after surgery or chemotherapy, or as a preliminary screening test. If this indicator is much elevated, it indicates that there may be malignant lesions, and in this case, it is necessary to further see whether the cancer can be treated surgically and the nature can be determined by postoperative pathology. Of course, malignancy cannot be determined by this indicator alone.