CA-125

Definition

• A glycoprotein tumour marker produced by coelomic epithelium and its derivatives

• Primarily used to support diagnosis and monitor treatment response in ovarian cancer

Causes of Elevated CA-125

• Malignancies

  • Ovarian, endometrial, breast and bowel cancers

• Benign Conditions

  • Liver cirrhosis with ascites

  • Ovarian cysts

  • Pelvic inflammatory disease

  • Uterine fibroids

  • Endometriosis and adenomyosis

  • Pregnancy, particularly in the first trimester

  • Peritoneal irritation from infections or inflammatory processes

• Normal Variants

  • Mild elevations may occur during menstruation without underlying pathology

Clinical Utility and Limitations

• Limited specificity, as levels are elevated in both malignant and benign conditions

• Not recommended for screening in asymptomatic women

• Serial measurements are more useful than a single value in monitoring treatment response or detecting recurrence

• Variability due to menstrual cycle and pregnancy necessitates clinical correlation

Investigations and Interpretation

• Serum assay with normal levels typically <35 U/mL

• Should be interpreted alongside clinical history, examination and imaging

• Elevated levels in the presence of a pelvic mass increase suspicion for ovarian malignancy

• Serial measurements guide management decisions in known ovarian cancer

Monitoring and Follow-Up

• Regular monitoring is essential in ovarian cancer to assess treatment efficacy and detect relapse

• In benign conditions, CA-125 levels usually normalise with resolution of inflammation

• Changes in CA-125 must be correlated with clinical and imaging findings

Notes:

• CA-125 is most valuable in the first 6 weeks of pregnancy for confirming intrauterine pregnancy

• In liver cirrhosis, elevated CA-125 is typically secondary to peritoneal irritation from ascites

• Combining CA-125 with other markers and imaging enhances diagnostic accuracy for pelvic masses

• CA-125 should be used as part of a comprehensive evaluation rather than in isolation

• Awareness of assay variability and influencing factors, such as hormonal fluctuations, is important in interpretation