Immunoreactive inhibin-production in post-menopausal women with malignant epithelial ovarian tumors

In post-menopausal women with a malignant epithelial ovarian tumor the follicle stimulating hormone (FSH) level was found to be significantly lower compared with healthy controls. We demonstrated immunoreactive (i.r.) inhibin in 20% of controls which was elevated to 60% of women with an ovarian tumor and correlating strongly to FSH in the tumor group (P = 0.0002). Steroid hormone levels were comparable in the two groups. In women with ovarian tumors the survival time for the i.r. inhibin-producing women was found to be 4.6 years compared with 0.9 year, or 5.1 times longer than in the non-producing women (P = 0.002). The site of i.r. inhibin production in these post-menopausal women is unknown, but i.r. inhibin production by the developing ovarian tumor or by the post-menopausal ovary may be regarded as a defense mechanism against an elevated gonadotrophin level (the gonadotrophin theory) which would promote further tumor growth. The recent suggestion that the alpha subunit of inhibin is a tumor suppressor gene is consistent with these results. The serum i.r. inhibin or alpha subunit concentrations might be used as an aid to diagnosis or as a prognostic indicator of survival in women with an ovarian carcinoma.