CA-125 stands for cancer antigen-125. It is a protein that serves as a non-specific indicator of pelvic inflammation.
Key aspects of CA-125 in the context of gynecological malignancies include:
- Clinical Significance: In patients with ovarian cancer, CA-125 levels are grossly correlated with the volume of the disease.
- Prognostic Value: A patient’s prognosis and response to chemotherapy can be predicted by the rate of decline in CA-125 levels. A better survival outlook is associated with levels normalizing to a standard range of 0–35 IU/mL following three cycles of therapy, while a slow response or failure to normalize after six cycles indicates a worse prognosis.
- Monitoring and Surveillance: CA-125 is used to monitor for disease progression or biochemical recurrence following complete remission. Elevations in this marker often pre-date clinical symptoms by several months.
- Screening Limitations: Routine CA-125 screening is not recommended for the general population because the test is not sensitive or specific enough to warrant large-scale programs. It can be elevated by non-cancerous conditions, including pelvic inflammatory disease or benign fibroids.
- Interpretation: Because of significant laboratory variation, CA-125 levels should ideally be drawn at the same laboratory for trends to be interpreted meaningfully for a specific patient.