Inhibin forms in serum from postmenopausal women with ovarian cancers

Clin Endocrinol (Oxf). 1999 Mar;50(3):381-6. doi: 10.1046/j.1365-2265.1999.00656.x.


Background and objective: Previous studies have shown that serum inhibin as measured by alpha subunit-directed radioimmunoassay (RIA) and inhibin A ELISA was elevated in postmenopausal women with mucinous and granulosa cell cancers, with the RIA showing a more frequent elevation than the inhibin A ELISA. It was thus hypothesised that these cancers may also produce inhibin B or the free alpha subunit. The aim of the study was to identify the forms of inhibin found in a range of ovarian cancers using a range of inhibin assays with varying specificities.

Design: Serum samples obtained from women with ovarian cancer were assayed by inhibin B ELISA and Pro-alpha C subunit ELISA and compared with inhibin RIA and inhibin A ELISA.

Patients: Blood samples were obtained from 34 postmenopausal women (> 55 years) with no history of endocrine disease and from women with ovarian serous cystadenocarcinomas (n = 66), mucinous cystadenocarcinomas (n = 20), granulosa cell tumours (n = 9-11), miscellaneous ovarian cancers (n = 46) and non ovarian cancers (n = 23).

Measurements: Inhibin B and inhibin Pro-alpha C subunit levels were determined by ELISA and compared to values obtained by RIA and inhibin A ELISA. Cancers were discriminated from controls based on values obtained 2SD above the geometric mean of the control values.

Results: Granulosa cell tumours were detected by RIA and inhibin B ELISA (100%), Pro-alpha C ELISA (90%) and inhibin A ELISA (77%). Mucinous tumours were detected by RIA (70%), inhibin B ELISA (60%), Pro-alpha C ELISA (55%) and inhibin A (20%). Serous tumours were detected by RIA (35%) and the other assays (< 15%). Miscellaneous tumours were detected by RIA (41%) and other assays < 30%.

Conclusions: Ovarian neoplasms may produce a variety of peptides related to the inhibins, including dimeric inhibin A and B. Inhibin B is detected in more ovarian cancers than inhibin A but does not discriminate as well as the alpha subunit directed assays. The higher discrimination index obtained with the RIA compared to the Pro-alpha C ELISA suggests that assays detecting all inhibin forms containing the alpha subunit and not just those detecting the Pro-alpha C subunit will provide the most useful detection method.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Enzyme-Linked Immunosorbent Assay / methods
  • Female
  • Follicle Stimulating Hormone / blood
  • Granulosa Cell Tumor / blood
  • Granulosa Cell Tumor / diagnosis*
  • Humans
  • Inhibins / blood*
  • Middle Aged
  • Neoplasms, Cystic, Mucinous, and Serous / blood
  • Neoplasms, Cystic, Mucinous, and Serous / diagnosis*
  • Ovarian Neoplasms / blood
  • Ovarian Neoplasms / diagnosis*
  • Peptides / blood
  • Postmenopause / blood*
  • Predictive Value of Tests
  • Prostatic Secretory Proteins*
  • Radioimmunoassay


  • Peptides
  • Prostatic Secretory Proteins
  • beta-microseminoprotein
  • inhibin-alpha subunit
  • Inhibins
  • Follicle Stimulating Hormone