CA 15-3
What this test measures
CA 15-3 is a protein shed by breast tissue cells. Tumour markers are proteins that can rise for many reasons, most of them not cancer. Specialists mainly use them to follow a condition that has already been identified, and a single value cannot answer a screening question on its own.
Why doctors request it
Specialists use it to follow breast cancer after treatment. It is not a screening test and is not used to look for breast cancer in the first place.
What commonly pushes it up
- Benign breast conditions
- Liver disease and some lung conditions
- Pregnancy and breast-feeding
- Breast cancer that has spread
What commonly pushes it down
- Successful treatment of a condition that raised it
Everyday reasons for a value outside the range
- It is normal in most early breast cancers, so it cannot screen
- Benign conditions raise it
About the sample
No fasting needed.
Upload a photo or PDF and see every line against the range your lab printed, explained in plain English. First report free.
Read my report freeThis is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.