CA-15.3
CA-15.3 is a tumour marker primarily used to monitor breast cancer treatment and detect recurrence. Rising levels may indicate disease progression. A simple blood test with no special preparation needed.
12 hours
Turnaround
Blood
Sample
What the CA-15.3 test tells you
CA-15-3 is a fragment of MUC1, a large mucin protein anchored in the membrane of glandular cells, including those of the breast. Normal breast tissue makes MUC1 in modest amounts and keeps most of it on the cell surface. Breast cancer cells make considerably more and shed pieces into the circulation, and it is those shed fragments that the blood test measures.
Its recognised role is in advanced or metastatic breast cancer, where it is used to follow disease that is already known about rather than to find it. A baseline is established, then values are repeated during treatment. A falling trend supports that therapy is controlling the disease; a sustained rise, confirmed on repeat testing, may be an early sign of progression and prompts imaging. Because a temporary rise can occur in the first weeks of effective chemotherapy as tumour cells break down, a single upward move is never acted on by itself.
This test has no place in screening and cannot make a diagnosis. Many early breast cancers do not raise it at all, so a normal value gives no reassurance that cancer is absent. In the other direction, a raised value very often has a harmless explanation: benign breast conditions such as fibroadenoma, chronic liver disease and cirrhosis, pregnancy and breastfeeding, some autoimmune conditions, and several other cancers can all push it up. Using it to check for cancer in someone with no symptoms and no diagnosis leads to false alarms and investigation that was never needed. It is a tool your doctor uses within a wider picture, read alongside examination, imaging and how you actually feel, and the trend over repeated tests always means more than one number.
Ordered primarily for patients undergoing treatment for metastatic breast cancer to assess whether therapy is working or the disease is progressing.
In advanced breast cancer, serial values give an objective read on whether the disease is responding or progressing between scans.
A trend that falls after starting therapy supports that the treatment is working, complementing rather than replacing imaging.
A confirmed, sustained rise can appear before progression becomes visible on imaging, prompting earlier reassessment by your oncologist.
A value taken before treatment starts is what later samples are measured against, which is what makes any later trend meaningful.
Reasons your doctor may request the CA-15.3 test
Your doctor may order this test for any of the reasons below. Some are routine checks, others follow specific symptoms or an earlier result.
Treatment response & follow-up
Monitoring treatment response in diagnosed metastatic or advanced breast cancer.
Follow-up after treatment for breast cancer, where your oncologist includes it in a surveillance plan.
Suspected progression
Investigating suspected progression when symptoms or examination findings change.
Baseline before therapy
Establishing a baseline value before systemic therapy begins.
No fasting window — pick any slot that suits you, online or on WhatsApp.
A DHA-licensed nurse collects your sample at home or in the office — free home collection.
A physician-reviewed, easy-to-read report lands securely by WhatsApp and email.
CA-15.3 is mainly used to monitor breast cancer treatment.
Ranges are a guide — your physician interprets your result alongside your symptoms and history.
What a higher result can point to
- Benign breast conditions, including fibroadenoma and other benign breast disease.
- Chronic liver disease and cirrhosis, which are common non-cancerous reasons for a raised value.
- Pregnancy and breastfeeding, and some autoimmune conditions.
- Metastatic or advanced breast cancer, particularly where it has spread to bone or liver.
- Other cancers, including those of the lung, ovary, pancreas and colon.
- A temporary rise in the early weeks of effective chemotherapy, as tumour cells break down.
These are possibilities, not diagnoses. A single value outside the reference range is interpreted alongside your symptoms, history and other tests — your doctor decides what it means for you.
What this test cannot tell you
- It is not a screening or diagnostic test; many early breast cancers do not raise it, so a normal value gives no reassurance that cancer is absent.
- Benign breast disease, liver disease, pregnancy, breastfeeding and several other cancers raise it, so an isolated high value establishes nothing on its own.
- Values from different laboratories and assay methods are not directly comparable, which can create an apparent change that is purely technical.
- A low result is the expected finding and has no independent significance.
Risks of the blood draw
- Mild bruising or brief soreness where the needle went in.
- Occasional lightheadedness, which settles after a few minutes of rest.
- Bleeding or infection at the site, which is rare with sterile single-use equipment.
- 1CA-15-3 is for monitoring diagnosed breast cancer, not for finding it in healthy people.
- 2A normal result does not mean breast cancer is absent, because many early cancers do not raise it.
- 3Benign breast conditions, liver disease, pregnancy and breastfeeding are common harmless reasons for a raised value.
- 4The trend across repeated samples is what matters, not any single value.
- 5Use the same laboratory over time so that a change is real rather than a difference in method.
Frequently Asked Questions
Everything you need to know about the CA-15.3 test. Can't find what you're looking for?
Talk to our team→No. It is not accurate enough to find breast cancer or to rule it out, and it is not used for screening. Many early cancers do not raise it, while benign breast and liver conditions do. Diagnosis relies on imaging and a tissue sample; this test is for following disease that is already known about.
Not necessarily. A temporary rise in the early weeks of effective treatment is well recognised and is thought to reflect tumour cells breaking down and releasing their contents. This is one reason a single rise is never acted on alone; your oncologist looks for a sustained trend confirmed on repeat testing.
Different manufacturers' assays measure the MUC1 fragment in slightly different ways, and their values are not interchangeable. A change on switching laboratories may be entirely technical rather than clinical. Staying with one laboratory throughout follow-up avoids this problem.
Yes, and often does. Chronic liver disease and cirrhosis are common causes, as are benign breast conditions, pregnancy, breastfeeding and some autoimmune diseases. Other cancers can raise it too. That is why it is always interpreted alongside your clinical picture rather than on its own.
CA-15.3 is a tumour marker primarily used to monitor breast cancer treatment and detect recurrence. Rising levels may indicate disease progression. A simple blood test with no special preparation needed.
Ordered primarily for patients undergoing treatment for metastatic breast cancer to assess whether therapy is working or the disease is progressing.
No, fasting is not required for the Breast Cancer Marker test, so you can eat and drink normally beforehand.
The Breast Cancer Marker test uses a blood sample, collected quickly by our DHA-licensed phlebotomist with minimal discomfort.
Results for the Breast Cancer Marker test are typically ready within 12 hours. You will receive a secure digital report, and your Smart Report highlights anything outside the normal range.
The Breast Cancer Marker test is AED 230, which includes free home sample collection and a physician-reviewed report. You can also build a custom panel and pay only for the markers you choose.
Yes. A DHA-licensed phlebotomist can collect your sample at home or the office anywhere in Dubai at no extra cost, 7 days a week. See how it works.
It is commonly chosen by adults & at-risk groups. If you are not sure it is right for you, our care team is happy to advise.
Add the Breast Cancer Marker test to your cart and complete the short booking wizard, choosing home collection or a lab visit. Guest checkout lets you book without creating an account.
Yes. It is processed at our EIAC-accredited laboratory (ISO 15189:2022) under DHA license 0046381 and verified by board-certified pathologists.
Every report includes reference ranges and plain-language notes. If you have questions, our care team can arrange a clinician review — just get in touch.
Absolutely. Add it to a curated health package or bundle it with any of our 160+ biomarkers, often from a single sample in one visit.