CLINICAL AND PATHOPHYSIOLOGICAL ASPECTS OF INHIBIN

Inhibin is a peptide hormone normally produced by the ovary. We have p reviously reported that serum inhibin concentrations are elevated in p atients with granulosa cell tumours of the ovary. The aim of this stud y was to measure serum inhibin in a prospective, consecutive series of 200 patients admitted for suspected ovarian cancer. The serum inhibin radioimmunoassay had a sensitivity of 77 mu/l. The median effective d ose was 640 mu/l, while within- and between-assay coefficients of vari ation in the region of maximal assay precision were 4.3% and 4.3%, res pectively. The average effective doses (10 and 90%) in 35 consecutive assays were 211 and 1908 mu/l, respectively. We designated a serum inh ibin concentration of greater-than-or-equal-to 130 mu/l as pathologica l in castrate or functionally agonadal women. Serum inhibin concentrat ions were elevated in 12 of 13 post-menopausal patients with mucinous cystadenocarcinoma of the ovary. By contrast, elevated serum inhibin v alues were found in only nine of 65 women with non-mucinous epithelial ovarian cancers. All patients showed a fall in serum inhibin levels t o below 130 mu/l by 1 week after surgery. In post-menopausal women (n = 54) with proven ovarian cancer, serum inhibin concentrations correla ted negatively with serum FSH and the clinical stage of their disease (P < 0.05). By contrast, serum inhibin correlated positively with seru m oestradiol and progesterone (P < 0.001) but there was no correlation between serum inhibin and serum CA-125 values. We conclude that serum inhibin concentrations are typically elevated in patients proven to h ave mucinous cystadenocarcinoma of the ovary. Serum inhibin values fal l after cytoreductive surgery in malignant, borderline and benign ovar ian neoplasms. Serum inhibin appears to be a useful tumour marker of m ucinous cystadeno-carcinoma of the ovary.