Cancer antigen 15-3 (CA 15-3)
CA 15-3 is a high molecular weight (300-450 kDa) transmembrane glycoprotein encoded by the MUC1 gene. It is defined by reactivity with 2 monoclonal antibodies, DF3 and 115D8. CA 15-3 is expressed predominantly in breast cancer (raised in 30 % of localised disease, 75 % metastatic), though primary tumours of the lung, colon, pancreas, liver and endometrium may also give rise to elevations of CA 15-3.
Elevations of CA 15-3 values have been reported in individuals with non-malignant conditions such as cirrhosis, hepatitis, autoimmune disorders and benign diseases of the ovary and breast. While increasing CA 15-3 can be the earliest sign of metastatic disease in ~70 % patients, there is little evidence showing that early diagnosis of progressive disease positively impacts survival or quality of life.
Breast cancer
Diagnosis: since CA 15-3 may be elevated in normal individuals and benign conditions, and there is a low incidence of CA 15-3 elevation in early stage breast cancer, CA 15-3 should not be used for screening.
Treatment monitoring: when serum CA 15-3 level is elevated it may be used to monitor response to therapy in combination with imaging and clinical examination. For patients with metastatic disease in whom CA 15-3 is being monitored, the marker should be determined prior to each chemotherapy course and at 3 month intervals.
Surveillance: despite the lack of high level evidence, many patients opt to have serial levels of CA 15-3 determined following surgery.
<32 kIU/L
Abbott Alinity
Record last updated
August 14, 2025
Sample Container
5ml SST Vacutainers (Gold / Yellow top)
Sample Container
6ml Plain Vacutainers (Red top)
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Test Results
Yes, we have a Pathology User Guide
Yes. Please email your request to Imperial.nwlpcustomerservice@nhs.net
Results are communicated to clinical staff and are normally not communicated direct to patients either on telephone requests or in written report. If you need to contact us please click here to view the contact details page
Please contact the Customer Service Team Monday to Friday from 8:30am – 6:00pm on 0203 313 5353. Alternatively, see the Pathology User Guide for how to contact the relevant department. If advice is not urgent you can also email your query to Imperial.nwlpcustomerservice@nhs.net
Additional tests may be added by discussion with the relevant laboratory. The time limit for adding additional tests to a sample already received in the laboratory will depend on the type of sample and the department it was sent to.
Information on the repertoire of tests performed by pathology, including reference ranges, turnaround times and specimen requirements, can be found in the test directory.
Different tests have different sample stability requirements. If a comment on results indicates that the sample was delayed, the links below will indicate which tests may have been affected. This information is for serum or plasma samples.
For some tests, the impact of delay is consistent and these are marked with an arrow:
↑ indicates tests where delayed centrifugation results in falsely elevated results and the true level is likely lower than that reported.
↓ indicates tests where delayed centrifugation results in falsely lowered results and the true level is likely higher than that reported.
If there is no arrow, the true level may be lower or higher than reported.
Please interpret results with caution and consider the impact of any uncertainty.
The comment on the report will state how delayed the sample was. Please click the relevant link below to see which other tests may have been affected.
| >8h | >12h | >24h | >48h | >72h |
Phlebotomy services are not managed by NWLP. For further information please see:
Imperial College Healthcare Trust Phlebotomy services
Chelsea and Westminster Hospital NHS Foundation Trust Phlebotomy services
NWLP operates UKAS accredited medical laboratories as per the references below. The current scope of accreditation for all NWLP’s laboratories can be found on the UKAS website.
UKAS accredited medical laboratory/medical diagnostic service:
- Clinical Biochemistry No. 8673
- Haematology and Blood Transfusion No. 8674
- Infection & Immunity Sciences (Including Immunology, Virology, Microbiology and Histocompatibility and Immunogenetics ) No. 8659
- Cellular Pathology (Including Histopathology, Cytology and Molecular Pathology) No. 9615
If you require copies of our certificate of accreditation and associated documentation please contact Imperial.nwlpcustomerservice@nhs.net.
UKAS requires the laboratories to be accredited for a particular repertoire/scope (ISO15189), any changes or additions to repertoire require assessment by UKAS (extension to scope).
The BD Hospital Tube Guide, BD GP Tube Guide and BD Paediatric Tube Guide provide visual references to the correct tube types and collection instructions.
Home testing
INSTRUCTION SHEET FOR BLOOD SAMPLE COLLECTION
We also have two instruction videos available (one with subtitles and one without) – please click on the links to view the videos on Google.
Our accreditations
Upholding excellence in diagnostic standards
Our laboratories are accredited by the UK Accreditation Service (UKAS) against the international standard ISO15189:2022. UKAS is the accreditation body for the UK that assesses medical laboratories.
Find out more about our accreditations on the UKAS website.
UKAS website