Use of CA 125 to monitor patients with ovarian epithelial carcinomas

The CA 125 radioimmunoassay has been increasingly used to monitor the course of patients with ovarian epithelial carcinomas. The purpose of this report is to describe our experience in the use of this assay and to better define its clinical utility. Fifty-one patients had serum CA 125 follow-up during primary chemotherapy. All 51 patients demonstrated either a normal CA 125 level at the completion of chemotherapy or a substantial fall in CA 125 values with treatment. In 48 of 51 patients, the drop in CA 125 levels was temporally related to the clinical regression or remission of tumor. Forty of these patients underwent second-look laparotomy; 23 patients (58%) had residual disease. A total of 45 patients had serum CA 125 determinations at the time of second-look laparotomy. Eight patients with microscopic disease and 11 of 18 patients with gross residual disease had a "negative" (less than 35 U/ml) CA 125 level. The predictive value of an elevated CA 125 level was 1.00. However, the predictive value of a negative value was only 0.50. Hence, a negative CA 125 level cannot be a substitute for a second-look laparotomy. Only 7 of 18 patients (39%) with gross residual disease at second-look surgery had an elevated CA 125 level. Patients with an elevated CA 125 and gross residual tumor at the second-look laparotomy uniformly demonstrated large, bulky disease. Furthermore, the survival of patients with gross residual disease at second-look laparotomy correlated with the preoperative CA 125 value. Serum CA 125 determinations also show promise in the follow-up of patients with a negative second-look laparotomy. The serum CA 125 level from patients with a "negative" second-look laparotomy can become elevated months before recurrent disease is appreciated.