A tumor marker used to monitor breast cancer.
Cancer antigen 15-3, or CA 15-3, is a protein shed into the blood by certain cells, including breast tissue. Small amounts are present in healthy people.
It is measured as a tumor marker, most often in the context of breast conditions, but it is not specific to cancer.
CA 15-3 is used mainly to monitor people already diagnosed with breast cancer, to watch response to treatment and check for return. It is not a screening test for healthy people and is often normal in early breast cancer.
Mild rises are common and often benign, seen with liver disease, some non-cancer breast and ovarian conditions, and other illnesses. A high or rising level needs a doctor to interpret in the full picture.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
Ranges are guidance only. CA 15-3 is an upper-cutoff marker.
| Group | Common upper guide (SI) |
|---|---|
| Adults | up to about 30 kU/L (U/mL) |
The exact cutoff depends on the assay. Aligned to German laboratory practice (DGKL).
Liver disease and some benign breast, ovarian, and other conditions can raise CA 15-3. It is often normal in early cancer, so a normal result does not rule cancer out. Results from different assays are not interchangeable.
Sometimes read alongside CEA when monitoring breast cancer, and always with imaging and clinical history.
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