CA 125

What it isA glycoprotein shed by ovarian and other epithelial cells, particularly when those cells are malignant or inflamed.

DoesActs primarily as a monitoring tool for ovarian cancer treatment response; not a reliable screening test.

GoodA low CA 125 in someone with known ovarian cancer signals treatment response or disease control.

BadElevated CA 125 has many causes — ovarian cancer, endometriosis, pelvic inflammatory disease, menstruation, pregnancy, ascites — making it poor for screening but useful for monitoring.