CA-125 is elevated in a 55-year-old woman found to have a pelvic mass. The specificity of CA-125 for epithelial ovarian cancer is limited because CA-125 can be elevated in benign conditions. The most common benign gynaecological condition causing false-positive CA-125 elevation is:

• A Endometriosis ✓
• B Uterine leiomyoma
• C Polycystic ovarian syndrome
• D Cervical dysplasia

Explanation

CA-125 (cancer antigen 125) is a mucin glycoprotein expressed on coelomic epithelium and mesothelium. Any condition that irritates peritoneal or pleural mesothelium can elevate CA-125. Endometriosis causes chronic peritoneal inflammation and ectopic endometrial tissue that expresses CA-125, commonly causing false-positive elevations that overlap with early ovarian cancer levels. This is a clinically important source of false positives in pre-menopausal women being investigated for pelvic masses. While leiomyomas can very mildly elevate CA-125, endometriosis is the most common gynaecological benign cause. PCOS and cervical dysplasia do not typically elevate CA-125.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

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Written and medically reviewed by the StethoPrep medical team.