Lab Test

Cancer Antigen 15-3

Cancer Antigen-Breast, CA 15-3

Test Codes

EPIC: LAB7017, Beaker: CA153




CA 15-3 levels should not be used as a screening test. Please see Clinical Utility section.

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Contact Laboratory for acceptability of other tube types.
See Minimum Pediatric Specimen Requirements for Microtainer® collection.

Physician Office/Draw Specimen Preparation

Let SST specimens clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged SST tube within two hours of collection. (Minimum: 0.4 mL)

Preparation for Courier Transport

Transport: Centrifuged SST tube, refrigerated (2-8°C or 36-46°F). (Minimum: 0.4 mL)

Rejection Criteria

  • Grossly hemolyzed specimens.
  • Lipemic specimens.
  • Red-top tubes with serum not separated from cells within two hours of collection.
  • Specimens not collected and processed as indicated.

In-Lab Processing

Let SST specimens clot 30-60 minutes. Centrifuge SST tubes and Microtainers® to separate serum from cells. Deliver immediately to the appropriate testing station.


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Dearborn Chemistry Laboratory

Royal Oak Automated Chemistry Laboratory


Results available in 24 hours.

Reference Range

Less than or equal to 31.0 U/mL.

Test Methodology

Chemiluminescent Immunoassay (CLIA).


The Abbott Architect CA 15-3 method is used. Results obtained with different assay methods or kits cannot be used interchangeably. 

The CA 15-3 assay is used to aid in the management of Stage II and III breast cancer patients. Serial testing for patient CA 15-3 assay values should be used in conjunction with other clinical methods for monitoring breast cancer. Patients with confirmed breast carcinoma frequently have CA 15-3 assay values in the same range as healthy individuals. Elevations may be observed in patients with nonmalignant disease. For these reasons, a CA 15-3 assay value, regardless of level, should not be interpreted as absolute evidence of the presence or absence of malignant disease. 

Clinical Utility

A 15-3 is detectable in serum and is widely used as a tumor marker for breast cancer. CA 15-3 has good specificity for both localized and metastatic breast cancer but does not exhibit good sensitivity for localized disease. Elevated CA 15-3 levels are found in the serum of about 60% of preoperative breast cancer patients and in 80% of patients with advanced metastatic breast cancer. CA 15-3 has been used as an indicator of distant metastases (M+ disease) in breast carcinoma and it measures the milk mucin secreted by the tumor. CA 15-3 is insufficiently sensitive in detecting primary or local disease and should not be used for routine screening, diagnosis of localized breast cancer, and follow-up of localized cancers. CA 15-3 is usually not elevated in patients with early stage breast cancer. Elevated levels are found in only 20% of patients with stage I and II disease.

Three possible uses of CA 15-3 are: as an adjunct to bone scan, to provide confirmatory results as a screen for metastatic breast cancer, and to monitor patients in follow-up. A rise in CA 15-3 to abnormal levels is highly suggestive of the development of distant metastases.

Elevated CA 15-3 levels have been associated with an increase relapse rate in patients who have gone into remission after initial therapy (lead time to relapse, 6.3 months) (1).


  1. Bates SE. Clinical applications of serum tumor markers. Ann Int Med 1991;115:623 638).

CPT Codes

LOINC: 83083-6


Last Updated


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