A fundamental and clinical investigation of cancer antigen 130 (CA 130) in the field of obstetrics and gynecology

: Two murine monoclonal antibodies designated 130-22 and 145-9 have been recently established by immunizing mice with a pulmonary carcinoma cell line (PC-9). With use of these monoclonal antibodies a sensitive sandwich immunoradiometric assay (IRMA) for cancer antigen 130 (CA130) was developed in Daiichi Radioisotope Laboratories (Tokyo). Applying this IRMA kit CA130 concentrations were measured in various body fluids with special reference to obstetrics and gynecology. The results are as follows; 1) A CA130-IRMA showed excellent sensitivity, specificity, reproducibility and analytical recovery. The standard dose-response curve covered the range from 10 to 500 U/ml. 2) Serum CA130 levels measured by this assay system were closely correlated with serum CA125 levels, demonstrating quite a high correlation coefficient (r = 0.965). 3) In pregnancy maternal CA130 levels increased moderately (less than 300 U/ml) in the first trimester, and thereafter fell rapidly under normal upper limit (less than 35 U/ml). Immediately after deliveries maternal CA130 levels showed a rapid increase, reaching 269 U/ml (mean levels). In amniotic fluids CA130 concentrations were greatly elevated (3,236 U/ml mean levels), while the levels were almost within normal limit in the umbilical arterial and venous blood. Accordingly it is necessary to measure Schwangerschaftsprotein 1 or human chorionic gonadotropin simultaneously with CA130 to rule out possible pregnancy. 4) CA130 was clearly localized in the amniotic epithelium and umbilical sheath and other placental tissue components remained negative for this antigen. Taking the lower CA130 levels in the umbilical sera into consideration, these immunohistochemical results suggest CA130 is not oncofetal but oncoplacental. 5) Serum CA130 levels increased pretherapeutically beyond 35 U/ml in 87% of ovarian malignancies, and in 56% of endometrial carcinoma. The mean levels of serum CA130 reached 931 and 143 U/ml, respectively. These data indicate clinical usefulness of CA130 as a tumor marker for those diseases. By contrast serum CA130 levels were lower, and very few cases showed serum CA130 levels over 35 U/ml in cervical cancer. 6) In endometriosis 88% of the cases demonstrated increased serum CA130 levels, indicating its usefulness for monitoring therapeutic courses, just like CA125. In benign gynecologic diseases over 80% of cases showed increased serum CA130 levels while only slight increase in serum CA130 was found (mean levels less than 84.0 U/ml). This disadvantage could be lessened by a combination assay with CA72-4 and others whose serum levels were very low in the benign diseases.