Total inhibin is a potential serum marker for epithelial ovarian cancer

Context: Total inhibin is the sum of precursors, subunits, and mature molecules of inhibin, which the normal ovary nearly stops to produce after menopause, whereas ovarian tumors still release. Objective: The aim of the present study was to evaluate whether the serum concentration of total inhibin has the sensitivity/specificity characteristics to become a diagnostic test for epithelial ovarian cancer in postmenopausal women. Design: This was a controlled, cross-sectional study. Setting: The study was conducted at the University of Siena. Patients: Blood specimens were collected from postmenopausal women with: 1) epithelial ovarian cancer, stage II- III ( n = 89); 2) benign ovarian tumors ( n = 25); 3) breast ( n = 10), colon ( n = 10), and stomach ( n = 10) cancers; and 4) controls ( n = 95). In the group of women with epithelial ovarian cancer, blood specimens were also collected after surgical removal of the tumor. In four cases of women with stage IIC mucinous tumor, blood specimens were collected during the follow-up time. Intervention: Total inhibin was measured by a new double- antibody ELISA. Results: Women with epithelial ovarian cancers showed serum total inhibin levels significantly higher than those with benign tumor or with nonovarian tumors or controls (P < 0.001). Patients with serous (n = 40) or mucinous tumors (n = 17) showed the highest total inhibin levels (P < 0.001). At 95% specificity, the total inhibin assay detected 37 of 40 (93%) serous tumors and 16 of 17 (94%) mucinous tumors. When total inhibin was combined with CA-125, all cases of serous and mucinous tumors were detected, and the overall sensitivity for epithelial ovarian cancers was 99% at 95% specificity. A significant decrease of total inhibin levels was shown in women with serous and mucinous carcinoma as result of surgery (P < 0.001). In the four women who were followed up, recurrence was associated to an increase of total inhibin levels. Conclusions: The present data show that total inhibin is a sensitive and specific marker of epithelial ovarian cancers in postmenopausal women. Total inhibin may therefore be combined with CA-125 for noninvasive diagnosis of epithelial ovarian cancer and may also be a useful serum marker to monitor disease-free intervals.