[CA 125 (cancer antigen 125), a new tumor associated antigen recognized by monoclonal antibody]

Concentrations in sera of a new antigen CA 125 related to ovarian carcinoma were measured by radioimmunoassay employing a monoclonal antibody, and its usefulness as a tumor marker in the diagnosis of ovarian carcinoma was discussed. False positive rate in sera of healthy controls (30 females) was 6.7% when the cut-off value was set at 35 U/ml and none of them showed any reaction over 65 U/ml. The mean value of CA 125 levels in sera from healthy controls was 23.5 +/- 8.7 U/ml. Positive rates for CA 125 in sera from various patients were 77.8% for ovarian carcinoma (14 of 18 cases), 18.2% for cervical carcinoma (2 of 11 cases), 62.5% for endometrial carcinoma (5 of 8 cases), 25.0% for myoma uteri (2 of 8 cases), and 7.7% for benign ovarian tumor (1 of 13 cases) when the cut-off value was set at 35 U/ml. Notably, there was a positive rate of 100% (9 of 9 cases) for serous cystadenocarcinoma. From the above, it was shown that the CA 125 radioimmunoassay (RIA) could detect ovarian carcinoma at an early stage and gave information concerning the histological class of carcinoma. Moreover, the CA 125 level in sera reflected clinical progress very well, and it was also suggested that the measurement of CA 125 level in sera reflected clinical progress very well, and it was also suggested that the measurement of CA 125 levels in sera was useful for the monitoring of ovarian carcinoma.