Objective: Our objectives were to define the optimal threshold level of CA 125 in Korean women for early detection of ovarian cancer and to evaluate the efficacy of this marker for differentating malignant from benign pelvic masses.
Study Design: Serum CA 125 levels were measured by immunoradiometric assay in total 1,049 samples which were collected from 550 apparently healthy women, 388 patients with benign pelvic masses, and 111 patients with gynecologic cancers.
Results: CA 125 levels were above 35 U/ml in 24(4.4%) of 550 healthy women, however only one exceeded 35 U/ml among women 50 years or older (specificity: 99.1%). Of women younger than age 50, 4(0.9%) had elevated CA 125 levels above 65 U/ml. Among 388 patients with benignpelvic masses, CA 125 levels above 35, and 65 U/ml were detected in 115 (29.6%), and 67 (17.3%) patients respectively. Using both cut-offs of CA 125, the rates of sensitivity were 91.1% and 88.9%, respectively, for patients with epithelial ovarian cancer. Using threshold of 126 U/ml which is the level of the 95th percentile for 216 patients with benign ovarian tumor, the rates of sensitivity and specificity for differentiating epithelial cancer from begnign ovarian tomor were 88.2% and 95.4%, respectively.
Conclusion: In terms of ovarian cancer screening, different threshold levels of CA 125 should be applied by age. Using 35 U/ml threshold for women age 50 or older and 65 U/ml threshold for those under 50 years of age, the specificityes of CA 125 are adequate for screening. In differentiating malignant from benign pelvic masses, using 126 U/ml cut-off could obtain the acceptable sensitivity and the better specificity.
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