Tumor Markers for Granulosa Cell Tumor of the Ovary
Inhibin B is the primary tumor marker that should be sent for patients with suspected or confirmed granulosa cell tumors of the ovary, as it demonstrates superior sensitivity (89%) and specificity (100%) compared to other markers. 1
Primary Tumor Marker
- Inhibin B should be measured as the first-line tumor marker, as it is secreted by granulosa cell tumors and reflects disease status more accurately than inhibin A 1, 2
- Inhibin B demonstrates 89% sensitivity at diagnosis and 85% sensitivity at recurrence, with 100% specificity 2
- Elevated inhibin B levels (>7 pg/mL in postmenopausal women) correlate significantly with presence of disease and tumor size 3
- Inhibin B elevations can predate clinical recurrence by 2-13 months, allowing earlier detection of disease progression 4, 2
Complementary Tumor Markers
- Anti-Müllerian hormone (AMH) should be considered as an additional marker, particularly when combined with inhibin B, as the combination improves detection of recurrent disease compared to inhibin B alone 5
- AMH demonstrates 92% sensitivity and 81% specificity for detecting macroscopic granulosa cell tumors 5
- Estradiol levels may be measured, especially in postmenopausal patients where elevated levels suggest hormone-producing tumor activity 6, 7
Age-Specific Considerations
For young patients with non-epithelial ovarian masses where germ cell tumors remain in the differential diagnosis, additional markers should be sent 1:
- Human chorionic gonadotropin (hCG)
- Alpha-fetoprotein (AFP)
- Lactate dehydrogenase (LDH)
These germ cell markers help distinguish granulosa cell tumors from dysgerminomas, yolk sac tumors, and other primitive germ cell tumors that require different treatment approaches 1
Clinical Utility and Monitoring Thresholds
- In postmenopausal women, inhibin B levels of 15.6 pg/mL, 44.6 pg/mL, and 73.6 pg/mL correspond to 25%, 50%, and 75% probability of abnormal CT imaging, respectively 3
- These thresholds can guide decisions about when to perform imaging studies during follow-up, avoiding unnecessary scans when inhibin B remains low 3
- Serial measurements are more valuable than single values, as rising trends indicate disease progression even before imaging changes become apparent 4, 8
Common Pitfalls to Avoid
- Do not rely on CA-125 as the primary marker for granulosa cell tumors, as it is non-specific and less sensitive than inhibin B for this tumor type 1
- Do not omit inhibin B testing in postmenopausal women with ovarian masses and endometrial hyperplasia or postmenopausal bleeding, as these clinical features suggest estrogen-secreting granulosa cell tumors 1
- Do not stop monitoring tumor markers after initial treatment, as granulosa cell tumors characteristically recur late (up to 20 years after diagnosis), and inhibin B elevations precede clinical recurrence by months 1, 6, 4