Serum/plasma cancer antigen 2729 (CA-27.29)
This test measures a specific protein marker (cancer antigen 27.29) that may be produced by certain cancers, including breast cancer.
["CA-27.29 helps monitor treatment response and detect recurrence in some patients with breast cancer."]
Key facts at a glance
- LOINC
- 17842-6
- Short code
- CA2729
- Synonyms
- Cancer Ag27-29 SerPl-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube without anticoagulant for serum; plasma separator tube (PST) or heparinized tube for plasma
- Units
- N/A
- Ref low
- 0
- Ref high
- 37
- Critical range
- 0.5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (e.g., chemiluminescent immunoassay or radioimmunoassay)
- CPT
- 86316
- SNOMED
- 11525-3
- Specimen volume
- 1.0 mL serum or plasma (minimum 0.5 mL)
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
What Is CA-27.29 Used For?
CA-27.29 is primarily used as a biomarker to track the progression or regression of certain cancers, particularly in patients with metastatic breast cancer. It may also be used in follow-up care to check for signs of cancer returning after treatment.
How Is the Test Performed?
A blood sample is drawn from a vein in your arm. The serum or plasma is then analyzed in a laboratory using an immunoassay method to detect the cancer antigen.
Why Might You Need This Test?
Your healthcare provider may order a CA-27.29 test if you have been diagnosed with breast cancer, especially if it has spread to other parts of the body. It may also be used during follow-up to monitor your condition after treatment.
What Do Results Mean?
Results can vary depending on your medical history and treatment. Higher levels may indicate cancer progression or recurrence, while lower levels may suggest treatment is working. Your doctor will interpret results in the context of your overall health and medical history.
Reference range
Typically < 37.0 U/mL is considered normal in healthy individuals. Reference values may vary by laboratory methodology and population.N/A
No special preparation required. Specimen may be collected at any time of day.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CA-27.29 plays a role in monitoring patients with breast cancer, particularly those with metastatic disease. While it is not a definitive diagnostic test, it provides valuable information for assessing disease activity and guiding treatment decisions. Levels may fluctuate due to treatment effects, so consistent monitoring is important.
Short name
CA-27.29
Frequently asked questions
What does a high CA-27.29 level mean?
How often should I get this test?
Can lifestyle changes affect CA-27.29 levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy