A CA125 measures a specific protein in the body that is found in higher concentrations specifically in
ovarian cancer tumors (not
kidneys, bladder, liver etc). But because it can increase in the body for other conditions besides ovarian cancer such as endometriosis, benign cysts, etc, an elevated reading alone cannot diagnose ovarian cancer. Likewise, women with certain types of ovarian cancer (MMMT, or clear cell, for example) may not have an elevated reading at all.