Our study was to determine the usefulness of CA 125 screening for asymptomatic female subjects. Though CA 125 has been used as a useful marker for the detection of ovarian cancer, its efficacy to detect early ovarian cancer in asymptomatic women has not been established.

From April 1995 to December 1997, a total of 13,038 subjects who visited our Center for Health Promotion were screened. Serum CA 125 level was measured by a radioimmunoassay kit (Centocor, USA). In most cases transvaginal ultrasound was done at the same time. The specificity, sensitivity and positive predictive value were obtained on the basis of normal CA 125 range between 2.4~36.3 U/ml.

1) Two cases of ovarian cancer were detected out of 13,038 subjects screened. One ovarian cancer patient showed 1,625 U/ml of CA 125 level, on the other hand, the other level patient showed 27 U/ml. 2) Therefore, the sensitivity, specificity, and positive predictive value were 50%, 97.3%, and 0.3%, respectively. Since 346 cases out of 13,038 screened subjects showed false positive results on the basis of the upper limit of normal CA 125 level set at 36.3 U/ml,the false positivity was 2.6%. 3) The CA 125 levels in false positive cases ranged from 36.3 U/ml to 352.8 U/ml with the mean value of 66.19+/-51.47 (S.D.). 4) The clinical features of the false positive cases included uterine myoma including adenomoysis (150), benign ovarian cyst (19), cervicitis (6), tuberculosis (3), pregnancy (2), and each one case of breast cancer, mammary cyst, endometritis, lung cancer, liver cirrhosis, pancreatic cancer, cervical cancer, renal cyst, uterine anomaly, and post TAH state. In the remainder of false positive 156 cases, no abnormal findings were observed. Among 258 pateints who underwent combined tests of CA 125 and transvaginal ultrasound, the sensitivity of ovarian cancer was 100%. 5) The false positive rate was lower in the older age group (>50) than in the younger group (<50).

The prevalance of ovarian cancer in our study was 0.0153% (15.3 per 100,000 population) which is comparable to the rate of 15.8 per 100,000 population reported by the Korean Medical Insurance Corporation. Although the CA 125 test by itself shows a low positive predictive value, its clinical usefulness as a screening test can be enhanced dramatically by the combined use of transvaginal ultrasound examination, especially in postmenopausal women.