Tumor markers, such as cancer antigen (CA) 125, are substances that can often be detected in higher than normal amounts in the blood, urine, or body tissues of some people with certain types of cancer. Currently, the main use of tumor markers is to assess how cancer is responding to treatment. CA 125 isn't specific to just one type of cancer. But women with ovarian cancer often have elevated CA 125 levels. Not all women with elevated CA 125 levels have cancer. Many other conditions can cause elevated CA 125 levels, including: Endometriosis; Pancreatitis; Pregnancy; Normal menstruation; Pelvic inflammatory; disease. Also, some women with ovarian cancer never have an elevated CA 125 level. Because of these limitations, this test isn't useful as a routine screening for ovarian cancer.