CA 27-29 — What It Means in Your Blood Test
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Tumour marker results are complex. This page explains what the test measures — your doctor or specialist interprets your result in full clinical context, alongside your history and other tests.
What CA 27-29 cannot tell you
CA 27-29 is not a screening test for breast cancer. Benign breast, liver and kidney conditions raise it, and a normal result does not rule cancer out. Your doctor reads it with an examination and imaging [ASCO, 2007].
This is a protein fragment shed from a cell-surface molecule, which benign conditions can also raise.
CA 27-29 behaves much like its sister test and helps monitor a known breast cancer. A raised value often has a benign cause, so it is read in context.
Also known as: Cancer antigen 27-29, Carbohydrate antigen 27.29, BR 27-29
This isn't a case where higher or lower is better. Your body keeps it in a narrow band, and both directions can matter.
Last reviewed: 2026-08-16
What does CA 27-29 do in your body?
A specialist uses CA 27-29 chiefly to judge whether treatment is helping a breast cancer that has already spread. Like CA 15-3, it is not a screening test and its trend matters most [ASCO, 2007].
What is CA 27-29?
CA 27-29 detects the same MUC1 surface protein as CA 15-3, using a different antibody. Several benign conditions of the breast, liver and kidney can raise it.
Why is CA 27-29 tested?
You may have this test to follow an already-found breast cancer, within a specialist's assessment. It is read with an examination and a scan.
What can raise CA 27-29
Common, non-cancer causes
- Benign breast conditions, such as fibroadenoma or a breast cyst [NACB, 2010]
- Long-standing liver disease, such as hepatitis or cirrhosis [NACB, 2010]
- Reduced kidney function [NACB, 2010]
- The first months of pregnancy [NACB, 2010]
Causes a doctor will also consider
- Breast cancer, which a specialist follows with CA 15-3 once it is known about, mainly when advanced [ASCO, 2007]
- Some other cancers, considered only in full clinical context [NACB, 2010]
One CA 15-3 reading means little alone. A specialist watches how it changes across tests, and reads it with an examination and imaging [ASCO, 2007].
What is a normal CA 27-29 range?
- India
- No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison.
- Global
- Laboratories often report against a general figure of about 30 U/mL, but benign liver and breast conditions can raise it; what a value means depends on the wider picture [NACB, 2010]
Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
Source: [ASCO, 2007]
What does your CA 27-29 value mean?
There is no widely-accepted set of value bands for this parameter. Compare your result with the reference range printed on your own report, and discuss it with your doctor.
What does a high CA 27-29 result mean?
A raised CA 15-3 often reflects a benign breast or liver condition. Your doctor weighs these first, with an examination and imaging, before any next step.
What does a low CA 27-29 result mean?
A low or within-range CA 15-3 is reassuring when following a known condition. It is still read with your examination and scan, as no single marker is enough.
What can affect your CA 27-29 result?
- Benign breast conditions
- Long-standing liver disease
- Pregnancy and breastfeeding
- The laboratory method — the same lab is used for monitoring
Questions to ask your doctor
About this result
- My CA 27-29 is [value] U/mL — read with my examination and scan, how concerned should we be?
- Could a benign breast, liver or kidney condition explain my CA 27-29?
What to do next
- Should the CA 27-29 be repeated at the same lab to show the trend?
- Do my result and imaging together point to any next step?
Frequently asked questions
- What is CA 27-29?
- CA 27-29 detects the same MUC1 surface protein as CA 15-3, using a different antibody. Several benign conditions of the breast, liver and kidney can raise it. You may have this test to follow an already-found breast cancer, within a specialist's assessment. It is read with an examination and a scan.
- What is a normal CA 27-29 test (breast marker) range?
- A typical adult range is around Laboratories often report against a general figure of about 30 U/mL, but benign liver and breast conditions can raise it; what a value means depends on the wider picture [NACB, 2010]. No India-specific national reference interval is published for this parameter; your lab's printed range is the most reliable comparison. Ranges vary by lab, method and equipment — the range printed on your own report is the one that applies to your result.
- What does a high CA 27-29 result mean?
- A raised CA 15-3 often reflects a benign breast or liver condition. Your doctor weighs these first, with an examination and imaging, before any next step.
- What does a low CA 27-29 result mean?
- A low or within-range CA 15-3 is reassuring when following a known condition. It is still read with your examination and scan, as no single marker is enough.
- What can affect your CA 27-29 result?
- Several everyday factors can influence it, including Benign breast conditions, Long-standing liver disease, Pregnancy and breastfeeding, The laboratory method — the same lab is used for monitoring.
Sources
- ASCO (2007) — ASCO 2007 Update of Recommendations for the Use of Tumor Markers in Breast Cancer
- NACB (2010) — NACB Laboratory Medicine Practice Guidelines: Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers
Part of the Tumour Markers
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