CA-125 concentrations in malignant and nonmalignant disease.

CA-125 is a high-molecular-mass glycoprotein expressed on the cell surface of some derivatives of embryonic coelomic epithelium. This tumor-associated antigen widely used to monitor ovarian carcinomas has been suggested as a promising noninvasive test that could differentiate benign from malignant conditions. Based on results of various studies, CA-125 measurement appears to be very useful in monitoring the response to therapy of ovarian carcinoma and for detecting tumor recurrence as exemplified in Case 1. However, because of the high frequency of false-positive results associated with many benign conditions, CA-125 is of little value as a screening test for ovarian carcinoma. A brief list of the most common benign conditions associated with CA-125 increase includes menstruation, pregnancy, benign pelvic tumors, pelvic inflammatory diseases, ovarian hyperstimulation syndrome, peritonitis, and many diseases leading to pleural effusion or ascites. According to several studies, a marked increase in CA-125 of greater than 1000 units/mL, as seen in Case 2, and even up to 5000 units/mL, could be seen in some benign conditions. This finding further limits the value of CA-125 as a potential noninvasive procedure to differentiate benign from malignant diseases. Although values up to 10,000 units/mL are occasionally seen in patients with ovarian carcinoma, we are reluctant to state that any concentration of CA-125 can be clearly diagnostic of malignancy.