CA 15-3 (Breast)
A tumour marker used mainly to monitor breast cancer and support follow-up under medical guidance.
CA 15-3 is a tumour marker used primarily to monitor breast cancer and support follow-up after treatment, providing useful data within medically guided care.
About the CA 15-3 (Breast) Test
This test measures CA 15-3, a protein that can be raised in breast cancer, particularly in more advanced or recurrent disease. Its main role is to monitor known conditions and follow-up rather than to screen the general population, since it may be normal in early disease and raised in some benign conditions. Results are interpreted by a doctor in the context of your history and other investigations.
Preparation and turnaround
A venous blood sample is required with no fasting generally needed. Results are usually available within two to three working days. Because CA 15-3 is a monitoring tool rather than a screening test, results are best reviewed with a doctor.
Frequently asked questions
What is CA 15-3 used for?
It is used mainly to monitor breast cancer and follow-up after treatment, rather than as a general screening test.
Can it be normal in early breast cancer?
Yes. CA 15-3 may be normal in early disease, which is why it is used for monitoring alongside other assessments rather than screening.
Is fasting required?
No fasting is generally required for the CA 15-3 test.
Some tests require fasting. We'll confirm any preparation (such as fasting for 8–10 hours) when we confirm your appointment. When in doubt, ask us at booking.
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