Inhibin A, B and pro-alphaC in serum and peritoneal fluid in postmenopausal patients with ovarian tumors.

Objective: To compare serum and peritoneal fluid concentrations of inhibin A, B, and pro-alphaC in women with ovarian tumors.

Methods: Serum and peritoneal fluid samples were taken from 41 postmenopausal women operated on for an ovarian tumor. Twenty-one patients with endometrial cancer formed a control group. Serum and peritoneal fluid inhibin A, B, and pro-alphaC concentrations, and serum FSH and tumor marker CA 125 (study group only) concentrations were analyzed.

Results: Inhibin A was found in low concentrations (median 4.1pg/ml, range <2-29pg/ml) in serum in most postmenopausal patients with epithelial ovarian carcinoma, whereas inhibin B was not measurable. Inhibin pro-alphaC circulated in high concentrations (median 125pg/ml, range 37->1000pg/ml). All inhibins were found in clearly greater concentrations in the peritoneal fluid than in serum. International Federation of Gynecology and Obstetrics (FIGO) stage III-IV and poor differentiation grade were associated with significantly lower concentrations of inhibin A and pro-alphaC in the peritoneal fluid compared with stages I-II or low grade. This correlation was not found in the serum concentrations of inhibin A or pro-alphaC. In the control group, no dimeric inhibins were found in serum, and pro-alphaC circulated in median concentrations of 47pg/ml (range 12-174pg/ml).

Conclusions: Postmenopausal patients with epithelial ovarian tumors had low concentrations of inhibin A and relatively high concentrations of inhibin pro-alphaC in serum. The peritoneal fluid concentrations of all inhibins far exceeded those in the serum. Relatively low concentrations of inhibin A and pro-alphaC in the peritoneal fluid of patients with ovarian cancer seem to be associated with high stage and grade and, to a lesser degree, with positive peritoneal cytology.