The murine monoclonal antibody OC 125 reacts with an antigen (CA 125) common to most nonmucinous epithelial ovarian carcinomas. An assay has been developed to detect CA 125 in serum. By this assay, only 1 per cent of 888 apparently healthy persons and 6 per cent of 143 patients with nonmalignant disease had serum CA 125 levels above 35 U per milliliter. In contrast, 83 of 101 patients (82 per cent) with surgically demonstrated ovarian carcinoma had elevated levels of antigen. In 38 patients with epithelial ovarian carcinoma monitored on 2 to 18 occasions during 2 to 60 months, antigen levels ranged from less than 1 to more than 8000 U per milliliter. Rising or falling levels of CA 125 correlated with progression or regression of disease in 42 of 45 instances (93 per cent). Determination of CA 125 levels may aid in monitoring the response to treatment in patients with epithelial ovarian cancer.

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An immunoradiometric assay (IRMA) has been used to determine circulating levels of the breast cancer-associated antigen, CA15-3. Of 1,050 normal control subjects, serum from 99 (9.4%) had CA15-3 antigen levels greater than 22 U/mL, while that from 58 (5.5%) and 14 (1.3%) had levels greater than 25 U/mL and 30 U/mL, respectively. In contrast, 115 of 158 patients (73%) with metastatic breast cancer had CA15-3 levels greater than 22 U/mL. Thirteen of 26 patients (50%) with only local metastases, 27 of 34 (79%) of those with only bone metastases, and 20 of 24 (83%) with hepatic metastases had CA15-3 levels greater than 22 U/mL. Furthermore, nine of 31 patients (29%) with primary breast cancer had CA15-3 levels greater than 22 U/mL. CA15-3 and carcinoembryonic antigen (CEA) levels were compared for the same patient population. Significantly more patients with metastatic breast cancer had elevated CA15-3 levels than had elevated CEA levels (P less than .001). Furthermore, the CA15-3 IRMA was more sensitive than the CEA assay in patients with only bone metastases, as well as those with only local metastases. Significantly more patients with primary carcinoma of the breast also had elevated CA15-3 than had elevated CEA levels (P less than .02). CA15-3 levels were greater than 22 U/mL in patients with nonmalignant conditions, including five of 25 patients (20%) with benign breast diseases, and 23 of 52 patients (44%) with benign liver diseases. Furthermore, CA15-3 levels were also greater than 22 U/mL in 24 of 54 patients (44%) with gastrointestinal (GI) malignancies, 12 of 17 patients (71%) with bronchogenic carcinoma, and 29 of 44 patients (66%) with epithelial ovarian carcinoma. Serial CA15-3 levels correlated with clinical disease course. Nineteen of 21 patients (91%) with tumor progression had at least a 25% increase in CA15-3 levels. Conversely, seven of nine patients (78%) with tumor regression had at least a 50% decrease in CA15-3 levels. Among 27 patients with stable disease, 16 (59%) had levels that did not vary by more than +/- 25% of the original CA15-3 levels. These results indicate that the CA15-3 antigen is a sensitive marker for the evaluation and monitoring of patients with breast cancer.

To investigate the sensitivity of the CA 125 immunoradiometric assay for occult ovarian neoplasia, serum CA 125 levels were retrospectively determined "blind" in specimens collected from 105 women who subsequently developed ovarian neoplasia, and from 323 matched controls. The distribution of CA 125 levels was very different between the case and control populations (p = 0.0001) over the entire collection-to-diagnosis interval (range 1-143 months). Median CA 125 levels for all cases, and for those collected more than 24, 36 or even 60 months prior to diagnosis, were always 18 U/ml or greater, compared with a median of 10.9 U/ml for controls. Half of the cases collected within the 18 months preceding diagnosis had CA 125 levels of more than 30 U/ml and one-third had levels greater than 65 U/ml. About one-fourth of those collected prior to 60 months before diagnosis had levels above 30 U/ml. In contrast, approximately 7% and 0.9% of controls had levels in excess of 30 or 65 U/ml, respectively. Elevations occurred in cases eventually diagnosed with localized or advanced cancer, and with borderline or obviously malignant disease. These results provide an insight into the preclinical biology of ovarian neoplasia that may help in designing methods for early detection of this disease, and demonstrate the usefulness of the JANUS serum bank as a resource in evaluating serum tests.