## Tumor Markers in Ovarian Cancer **Key Point:** CA-125 is the most widely used tumor marker for epithelial ovarian cancer (EOC), though it is neither highly sensitive nor specific in isolation. ### CA-125 Characteristics - **Elevation:** Present in 80–90% of advanced EOC (Stage III–IV) but only 50% of early-stage disease (Stage I–II) - **Specificity:** ~97% in postmenopausal women; lower in premenopausal women due to benign causes (endometriosis, menstruation, fibroids) - **Clinical Use:** Primarily for monitoring treatment response and detecting recurrence rather than screening or diagnosis - **Cutoff:** >35 U/mL is considered elevated ### Other Markers and Their Roles | Marker | Primary Use | Cancer Type | Sensitivity in EOC | |--------|-------------|-------------|--------------------| | **CA-125** | Monitoring EOC, recurrence detection | Epithelial ovarian | 80–90% (advanced) | | **AFP** | Diagnosis and monitoring | Germ cell, yolk sac tumors | Not useful for EOC | | **hCG** | Diagnosis and monitoring | Germ cell, choriocarcinoma | Not useful for EOC | | **CEA** | Colorectal, mucinous cancers | GI malignancies | Not primary for EOC | **High-Yield:** CA-125 is most useful for **serial monitoring** (trend over time) rather than a single value. A rising CA-125 after chemotherapy suggests recurrence; a falling level indicates treatment response. **Clinical Pearl:** In multivariate models, CA-125 combined with transvaginal ultrasound and clinical assessment improves diagnostic accuracy. Germ cell tumors (dysgerminoma, yolk sac tumor) and sex cord–stromal tumors require different markers (AFP, hCG, inhibin). **Warning:** Do not rely on CA-125 alone for diagnosis—benign conditions (endometriosis, peritonitis, cirrhosis) can elevate it. Always correlate with imaging and histology.
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