Lab Guide
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Test ID: Cancer Antigen 15-3, (CA 15-3)
Cancer Antigen 15-3, (CA 15-3)
Useful For

To monitor response to therapy of invasive breast cancer and assist in early detection of disease recurrence

Method name and description

Electrochemiluminescence immunoassay (ECLIA) intended for use on the cobas e 801 immunoassay analyzer. Patient specimen automatically prediluted 1:10 with Diluent Universal, biotinylated monoclonal CA 15‑3‑specific antibody, and a  monoclonal CA 15‑3‑specific antibody labeled with a ruthenium complex react to form a sandwich complex. After addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell/ProCell II M. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier. Results are determined via a calibration curve which is instrument specifically generated by 2‑point calibration and a master curve.

Reporting name

CA 15‑3

Clinical information

The CA 15‑3 values measured are defined by the use of the monoclonal antibodies (MAb) 115D8 directed against human milk fat globule membranes and MAb DF3 directed against the membrane fraction from human metastatic breast cancer. The 115D8 and DF3‑reactive determinants detected by the test are located on a glycoprotein having a molecular weight of > 400 kDa. The antigen is termed MAM‑6 and belongs to a subgroup of sialylated glycoproteins designated polymorphic epithelial mucin (PEM). Polymorphic epithelial mucins (PEMs) are normally found in the luminal secretion of glandular cells and do not circulate in the blood. When cells become malignant and their basal membranes permeable, PEMs are detectable in serum using the CA 15‑3 assay.

Specimen type / Specimen volume / Specimen container

Specimen type: Serum, Plasma

Minimum volume of sample: 1 mL

Serum: Plain tube (red or yellow top)

Plasma: Li‑heparin tube

 

Collection instructions / Special Precautions / Timing of collection

Collect blood by standard venipuncture techniques as per specimen requirements. When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.

Storage and transport instructions

Storage: 5 days at 2-8°C

              48 hours at 20‑ 25 °C

              90 days at ‑ 20 °C (±5)


Transport: 2-25°C  

Specimen Rejection Criteria

Grossly hemolyzed, icteric and lipemic samples, wrong collection container, insufficient sample and heat‑inactivated samples.

Biological reference intervals and clinical decision values

0-34.5 U/mL

(The testing method is an Electrochemiluminescence Immunoassay manufactured by Roche Diagnostics and performed on Cobas e801. Results determined by assays using different Manufactures or Methods may not be comparable.

 

Turnaround time / Days and times test performed / Specimen retention time

Daily (24/7)

Turn-around time:

Routine: One working day

Specimen Retention: 4 days