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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Ovarian carcinoma disseminates by direct seeding throughout the peritoneal cavity. It involves surfaces of the abdominal viscera, as well as the diaphragm. Epithelial ovarian carcinoma responds to multiple-agent chemotherapy, if tumor implants are reduced to 1.5 cm in any single location by cytoreductive surgery. Greater antitumor activity than that achieved by systemic administration may be obtained by increasing the dose and getting high concentrations of the chemotherapeutic agent directly to the site of the residual tumor. Oncologists have administered adriamycin into the peritoneal space using a permanent peritoneal dialysis catheter. Adriamycin added into two liters of dialysis solution can reach concentrations up to 400 times greater than those in plasma. The factor which limits the dose of intraperitoneal adriamycin is chemical peritonitis. Recently investigators have infused cis-diammine dichloro-platinum (CDDP) via the dialysis catheter. With this agent, four patients of 18 who had failed previous chemotherapy, showed an objective response. Finally, Corynebacterium parvum has also been administered intraperitoneally via the dialysis catheter. The permanent peritoneal catheter has at least two advantages: First, it permits intraperitoneal administration of the various chemotherapeutic agents, and second it permits easy sampling of the dialysis fluid for cytological analysis and for measurement of the peritoneal inflammatory activity, using antibody-dependent cell-mediated cytotoxicity assay. A new study now in progress will test the effect of recombinant interferon administered intraperitoneally to patients with ovarian cancer.