Monoklonale Antikörper in Diagnostik und Verlaufskontrolle des Ovarialkarzinoms. CA 125 als Tumormarker

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Abstract
The clinical validity of using the cancer antigen (CA) 125 — a surface antigen on malignant epithelial ovarian tumors — for diagnosis and follow-up of ovarian cancer was investigated in a cooperative study. Using a monoclonal antibody (OC 125) to detect CA 125, the sera of 850 patients were analyzed by immunoradiometric assay (IRMA-Kit Centocor). For 199 patients with ovarian cancer, a preoperative sensitivity of 83% and 74% resulted for the usual cut-off points (≥35 and ≥65 U/ml respectively). The positivity rates and quantiles correlated with the stage of disease (FIGO) and with the tumor debulking achieved at primary surgery. The most frequent histological types (serous cystadenoma and the undifferentiated carcinoma of the ovary) showed the highest positivity rates (80% and 90%, respectively, for cut-off at ≥65 U/ml). Elevated CA 125 values were found in 74% of the cases with a relapse and in 79% of the patients with advanced disease (cut-off, ≥65 U/ml) in the follow-up of ovarian cancer. We recommend cut-off at ≥65 U/ml, because the values for only 1% of the female healthy controls (n=251) were above this level. Also 17% of the patients with adnexitis and 8% with benign neoplasias of the ovary showed elevated titers. Therefore CA 125 should not be used for mass screening of ovarian carcinoma. However, it is a helpful laboratory tool in the diagnosis of recurrence and the surveillance of patients with ovarian cancer.