Clinical Significance

   It is used as a marker for ovarian cancer. (Evaluating patients' response to ovarian cancer therapy and Predicting recurrent ovarian cancer)

   However, CA 125 levels may also be high in other types of non-cancerous conditions, including menstruation, pregnancy, and pelvic inflammatory disease.

Specimen

   Serum

Stability

   Refrigerated (preferred) : 5 days

   Frozen : 180 days

Reference Range

   < 35 U/ml

Interpretation

   In monitoring studies, elevations of cancer antigen 125 (CA 125) above the reference interval after debulking surgery and chemotherapy indicate that residual disease is likely (>95% accuracy). However, normal levels do not rule out recurrence.

   A persistently rising CA 125 value suggests progressive malignant disease and poor therapeutic response.

   Physiologic half-life of CA 125 is approximately 5 days.

   In patients with advanced disease who have undergone cytoreductive surgery and are on chemotherapy, a prolonged half-life (>20 days) may be associated with a shortened disease-free survival.

Limitation

   Results cannot be interpreted as absolute evidence of the presence or absence of disease. CA 125 can be high in many normal or benign conditions (for example, pregnancy, menstruation, uterine fibroids, endometriosis and pelvic inflammatory disease).