A medical biochemistry test that measures the level of CA-125 in blood. As a tumor marker, it is interpreted alongside clinical and imaging findings, particularly for the diagnosis and follow-up of ovarian cancer.
Indication
- Initial assessment of ovarian cancer in patients with a detected pelvic mass
- Monitoring treatment response in patients diagnosed with ovarian cancer
- Surveillance for disease recurrence after surgery or chemotherapy
- Supplementary evaluation in conditions such as endometriosis or pelvic inflammatory disease, when clinically indicated
- Adjunct test in the differential diagnosis of ascites or pleural effusion
Preparation
- No fasting required
- Measurement during menstruation can result in physiological elevation; the appointment can be planned with the physician
- Recent gynecological intervention or abdominal surgery should be reported to the laboratory
How it's performed
- A venous blood sample is drawn from the arm
- Serum is separated and CA-125 levels are measured by immunoassay
- Results are reported in U/mL
- Findings are interpreted together with pelvic ultrasound, MRI, and clinical findings
Post-procedure
- Results are typically available within 1-2 business days
- In treatment-response monitoring, the test is repeated at set intervals (usually every 2-3 months)
- The trend (increase/decrease) is more informative than a single value
- An elevated value alone does not confirm cancer; further imaging and tissue diagnosis are essential
- Results are always interpreted together with the gynecologic oncology team
Risks
- Bruising or tenderness at the blood draw site
- Tumor markers should NOT be used for screening; their low specificity may cause unnecessary anxiety and unnecessary procedures
- Conditions such as endometriosis, pregnancy, menstruation, liver disease, or peritonitis can elevate the value (false positive)
- The value can be normal even in the presence of ovarian cancer (false negative)
FAQ
Does an elevated CA-125 mean cancer for sure?
No. Many benign conditions, including endometriosis, menstruation, pregnancy, liver disease, and peritonitis, can elevate CA-125. Results are interpreted together with imaging and clinical findings.
Is it used for screening?
No. CA-125 is not recommended as an ovarian cancer screening test in healthy women. Screening use risks false positive/negative results and unnecessary procedures.
How is it used for treatment follow-up?
In diagnosed patients, the trend over time (rising/falling) gives clues about treatment response or recurrence. Serial measurements are interpreted rather than a single value.
How long does it take to get results?
Results are usually available within 1-2 business days.
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