This is a protein measured in blood samples. It is produced by a variety of cells, but particularly by ovarian cancer cells. It is used as a tuomor marker to confirm the suspicion of ovarian cancer and to follow the presence of residual or recurrence of ovarian cancer after surgery. Its blood levels may be elevated in pregnant women and patients with breast and colorectal cancers, endometriosis, ovarian cysts, fibroids, cirrhosis, hepatitis, or pancreatitis. Normal range is 0-35 u/mL.