OC-125 as a diagnostic aid in the cytological evaluation of ascitic cells in patients with ovarian carcinoma

OC-125 is a monoclonal antibody raised against tumor cells from a patient with serous cystadenocarcinoma and reacting with an antigen CA-125 on the surface of ovarian epithelial cancer cells. We investigated whether immunohistochemical determination of CA-125 in cell samples from the peritoneal cavity could be used to discriminate between non-specific inflammatory changes in the mesothelium and malignant ovarian tumour cells. Three categories of patients were investigated: patients with disseminated serous or endometrioid ovarian carcinomas, patients with non-specific inflammatory changes in the peritoneal cavity and patients subjected to simple hysterectomy with no pathological changes in the mesothelium. In all cases of ovarian cancer CA-125 positive cells could be detected in the peritoneal fluid; none of the other categories showed positive reaction for CA-125. The results suggest that OC-125 may be a valuable adjunct in differentiating neoplastic from other cells in ascitic fluid from patients with some types of ovarian cancer.