[Diagnosis and follow-up of ovarian cancer by a combination assay of serum sialyl SSEA-1 antigen and CA125 levels].

We used a combination assay of serum sialyl SSEA-1 antigen (SLX) and CA125 levels, and evaluated the clinical usefulness of this technique for a diagnosis of ovarian cancer and follow-up of the patient with ovarian cancer. In 28 patients with ovarian tumors, the sera of 8 (66.7%) of 12 with ovarian cancer and 5 (71.4%) of the 7 with endometriosis (endometrial cyst) were positive for both SLX and CA125, but serum SLX level was 50 U/ml or less in all these 5 SLX-and-CA125 positive patients with endometriosis. The sera of all 9 patients with benign ovarian tumor were negative for both tumor markers. No patient with endometriosis was negative for both markers. The diagnostic accuracy (true positive rate X true negative rate) of the combination assay for ovarian cancer was 50.3% when the cut-off value of the serum SLX was 38 U/ml but improved to 81.8% when the value was set at 50 U/ml. From the above observations, a combination assay of serum SLX and CA125 is promising method for the differential diagnosis of malignant and benign ovarian tumors. Our results also suggest that to improve the diagnostic accuracy, the cut-off value of the serum SLX level should be 50 U/ml for ovarian tumors alone. We found following-up two cases of ovarian cancer that the serum SLX level is not affected by the ascites and inflammation. We expect that this combination assay of serum SLX and serum CA125 will be beneficial for diagnosis and follow-up of ovarian cancer.