Interest in
inhibin as a marker of ovarian
malignancy was stimulated by the description of elevated immunoreactive
inhibin levels in the sera of patients with granulosa cell tumours. Several groups have confirmed the value of serum
inhibin in the diagnosis and follow-up of patients with this uncommon
malignancy. Immunoreactive
inhibin levels are also frequently elevated in patients with
mucinous cystadenocarcinoma and less frequently in other forms of ovarian tumour. Assay of sera using the specific dimeric
inhibin assays has shown that ovarian tumours are able to secrete dimeric
inhibin particularly
inhibin B. The less specific alpha-subunit directed assays, however, most frequently show elevated concentrations. Used in combination with CA125 as a dual tumour marker, it appears in principle that
inhibin can be a useful diagnostic agent. Immunohistochemistry for the
inhibin subunits has been reported with increasing frequency as a helpful method to assess suspected ovarian stromal cell tumours. Its diagnostic accuracy for other types of ovarian
adenocarcinoma appears less reliable. Expression of the
inhibin subunit mRNAs has been demonstrated in a variety of ovarian
malignancies. The observation that
inhibin levels are elevated in
ovarian cancer has stimulated studies of their relevance to the molecular pathogenesis of these
malignancies. Findings to date have been largely negative with no evidence for activating mutations of the
FSH receptor or of the post-receptor signalling pathway
proteins.