Predictive value of CA 125 for ovarian carcinoma in patients presenting with pelvic masses.

Between November 1984 and May 1986, 56 patients presenting with a pelvic mass to the Gynecologic Oncology Service of McMaster University and the Hamilton Regional Oncology Center underwent laparotomy for possible ovarian cancer. All patients had blood drawn for CA 125 three days before operation. Levels above 35 U/mL were considered positive; CA 125 had a positive predictive value of 60%. False positives occurred in patients with nongynecologic malignancies and with benign gynecologic conditions. On the other hand, CA 125 had a negative predictive value of 100%, suggesting that this test may be useful in identifying those patients with pelvic masses at higher risk for malignancy, who may require transfer for surgery at a tertiary care center.