Medical biochemistry test measuring CA 15-3 levels in blood. As a tumor marker, it is interpreted alongside clinical findings, particularly for monitoring treatment response and recurrence in breast cancer.
Indication
- Monitoring treatment response in patients diagnosed with breast cancer
- Recurrence follow-up after surgery, chemotherapy, or radiotherapy
- Assessing disease course in patients with metastatic breast cancer
- Supportive testing in suspected conditions such as pleural effusion or bone metastasis
- Complementary information during treatment planning in advanced-stage patients
Preparation
- Fasting is not required
- Pregnancy or breastfeeding status should be reported to the laboratory
- Recent breast surgery or invasive procedures should be disclosed to the physician
How it's performed
- A venous blood sample is drawn from the arm
- Serum is separated and CA 15-3 levels are measured by immunoassay
- Result is reported in U/mL
- Interpreted together with clinical status, imaging, and other tumor markers (CEA when needed)
Post-procedure
- Results are typically available within 1-2 business days
- The trend over time (rise/fall) is more meaningful than a single value
- Generally measured at 2-3 month intervals during treatment follow-up
- When elevation is observed, it is confirmed with imaging
- Results are interpreted together with the medical oncology/breast surgery team
Risks
- Bruising or tenderness at the blood draw site
- Tumor markers are NOT used for screening; testing in healthy individuals is not recommended
- Levels may rise (false positive) in conditions such as liver disease, hepatitis, pregnancy, breastfeeding, and benign breast disease
- Levels may be normal in early-stage breast cancer (false negative); does not establish a diagnosis on its own
FAQ
Is it used for screening in healthy individuals?
No. CA 15-3 is not recommended for breast cancer screening. Use for screening can lead to false positive/negative results and unnecessary anxiety. Mammography is the standard method for breast cancer screening.
Does an elevated CA 15-3 always mean recurrence?
No. A single elevated value does not provide a definitive result. Liver disease, pregnancy, breastfeeding, and benign breast diseases can also raise it. It is interpreted together with the trend and imaging.
How often is it repeated?
In patients under treatment follow-up, it is generally performed at 2-3 month intervals based on physician recommendation.
When are the results ready?
Generally within 1-2 business days.
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