Skip to content
Intel Lab Diagnostics Dubai
Single Biomarker

CA-15-3

Breast Cancer Marker

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.

BLOOD24 HOURSNO FASTING
AEDAED230
  • Free home collection
  • Physician-reviewed report

24 Hours

Turnaround

Blood

Sample

About This Test

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.

Sample type
Blood
Measured in
U/mL
Turnaround
24 Hours
Fasting
Not required
Best for
Adults & at-risk groups
Why Get Tested?

Ordered primarily for patients undergoing treatment for metastatic breast cancer to assess whether therapy is working or the disease is progressing.

  • Following metastatic disease

    In advanced breast cancer, serial values give an objective read on whether the disease is responding or progressing between scans.

  • Assessing treatment response

    A trend that falls after starting therapy supports that the treatment is working, complementing rather than replacing imaging.

  • Early signal of progression

    A confirmed, sustained rise can appear before progression becomes visible on imaging, prompting earlier reassessment by your oncologist.

  • Establishing a baseline

    A value taken before treatment starts is what later samples are measured against, which is what makes any later trend meaningful.

When This Test Is Ordered

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.
Preparation
The short version
No prep needed.
  • Blood
  • Free home collection
  • No fasting
  • Results in 24 Hours
  1. 1
    Book any time

    No fasting window: pick any slot that suits you, online or on WhatsApp.

  2. 2
    We come to you

    A DHA-licensed nurse collects your sample at home or in the office: free home collection.

  3. 3
    Results in 24 Hours

    A physician-reviewed, easy-to-read report lands securely by WhatsApp and email.

Prep note
Physician reviewed

No fasting is required and you can eat and take your usual medicines as normal.

If you are being followed over time, consistency is what makes the result useful: try to use the same laboratory for every sample, since different assay methods give values that cannot be compared directly, and keep to the intervals your oncologist sets. Bring or have access to your previous results so the trend can be seen rather than a single figure.

Tell the team about recent chemotherapy, radiotherapy or surgery, any known liver disease, any benign breast condition, and whether you are pregnant or breastfeeding, since each of these affects how a value is interpreted. Drinking water beforehand makes the blood draw easier.

Understanding Your Results

A result in the Normal band, 0 to 30 U/mL, is what most people show, including many with early breast cancer, so it is not evidence that disease is absent. A result in the High band, 31 to 1000 U/mL, requires clinical correlation: benign breast conditions, chronic liver disease and cirrhosis, pregnancy and breastfeeding, some autoimmune conditions and several other cancers all raise CA-15-3, and a temporary rise is common in the first weeks of effective chemotherapy as tumour cells break down. This marker is used to follow disease that is already known about, so the trend across repeated samples (ideally run by the same laboratory, since methods are not interchangeable) carries the information rather than one reading. Your doctor interprets it with your examination, imaging, treatment history and how you feel.

SmartReport
30
Healthy zone15U/mLNormal
Reference ranges · U/mL
Normal
Within the normal range.
0–30
High
Elevated: requires clinical correlation.
31–1000

Ranges are a guide: your physician interprets your result alongside your symptoms and history.

Reading a High or Low Result

  • 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.

Limitations & Safety

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.
Key Points
  • 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.
Related Tests
View all
Book in 60 seconds

Know your CA-15-3.
No waiting room required.

A nurse comes to you, results land in 24 Hours, and a physician walks you through exactly what they mean.

AED230
Ask a clinician
FAQ

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.