Clinical evaluations of the tumor marker sialyl SSEA-1 antigen for clinical gynecological disease

Sialyl SSEA-1 antigen (SLX) is a highly specific tumor marker composed of sugar chain antigens that have Lewis X at their terminals and bind to sialic acid. This antigen is rarely detected in normal tissues, and is present in adenocarcinoma and fetal tissues. We studied the clinical usefulness of SLX in gynecological patients and obtained the following results. (1) The antigen was frequently positive in patients with ovarian cancer with a mean of 89.5 +/- 48.3 U/ml (72.8%, 8/11) and in those with endometriosis with a mean of 39.8 +/- 10.3 U/ml (75.0%, 6/8). (2) Among the gynecological malignancies, the percent positivity was low in those with cervical cancer (20.0%, 5/25), endometrial cancer (33.3%, 1/3), and cancer of the fallopian tube (33.3%, 1/3). (3) The antigen was negative in 20 with myoma uteri, 20 normal pregnant women, and 9 nonpregnant healthy women during the follicular, luteal, or menstrual phase. It was negative in 8 of 9 patients with benign ovarian cyst. False negative results were rare. (4) The SLX level was higher in the ascites than in the serum in patients with ovarian cancer and in those with benign ovarian tumors. (5) The serum SLX in patients with ovarian cancer, which was positive before tumor resection, became negative 2 weeks postoperatively. These results suggest that SLX is a tumor marker with a high specificity to adenocarcinoma of the reproductive organs.