What is the Cancer Antigen 19-9 Test?

Cancer Antigen 19-9 (CA 19-9) is a carbohydrate antigen produced by certain gastrointestinal epithelial cells. It is most commonly associated with pancreatic cancer but may also be elevated in other gastrointestinal malignancies, including bile duct, colorectal and gastric cancers.

The CA 19-9 blood test measures the concentration of this antigen in the bloodstream. It is not suitable as a general cancer screening test, but it plays an important role in assessing disease burden, monitoring treatment response and detecting recurrence in patients with known or suspected malignancy.

CA 19-9 levels are always interpreted in combination with imaging studies, clinical findings and other laboratory markers.

Why do I need a test for Cancer Antigen 19-9?

You may need this test if pancreatic or gastrointestinal cancer is suspected or already diagnosed. CA 19-9 is particularly valuable for monitoring disease progression and evaluating how well treatment is working over time.

The test is also used during follow-up after cancer treatment to detect early signs of recurrence. Rising CA 19-9 levels may indicate increasing tumour activity, while decreasing levels often suggest a favourable response to therapy.

Symptoms and scenarios where testing is recommended:

• Suspected pancreatic cancer
• Monitoring known pancreatic malignancy
• Biliary tract or gastrointestinal cancer assessment
• Unexplained weight loss
• Persistent abdominal or back pain
• Jaundice or abnormal liver function tests
• Monitoring response to chemotherapy or surgery
• Cancer recurrence surveillance

Benefits of the CA 19-9 Test

• Key marker for pancreatic cancer monitoring
  Widely used to track disease activity in pancreatic malignancy.
• Assesses treatment response
  Falling levels often reflect effective therapy.
• Detects disease progression or recurrence
  Rising levels may indicate tumour growth or relapse.
• Supports clinical decision-making
  Helps guide imaging and treatment adjustments.
• Complements other tumour markers
  Used alongside markers such as CEA or CA 72-4.
• Non-invasive monitoring tool
  Requires only a simple blood sample.
• Useful for long-term follow-up
  Enables trend analysis over time.
• Provides objective disease activity data
  Allows comparison of results across treatment stages.

Step-by-Step: How Testing Works

Choose your preferred testing method

You can attend one of our UK partner clinics or arrange a home or hotel visit with a mobile phlebotomist.

Option 1 – In-Clinic Blood Draw

1. Select your nearest UK clinic and book an appointment.
2. A clinician or phlebotomist collects a venous blood sample.
3. The sample is analysed for CA 19-9 levels.
4. Results are delivered securely online.

Option 2 – Home or Hotel Phlebotomy (+£60)

1. Book a UK-wide home or hotel visit at a convenient time.
2. A trained phlebotomist collects your blood sample on-site.
3. The sample is packaged and transported to the laboratory.
4. Results are uploaded digitally without the need to travel.

Access your report

You can download and share your results with your GP, oncologist or specialist.

Your Results Explained

Low Levels

Low CA 19-9 levels are considered normal.
This suggests no biochemical evidence of active CA 19-9-producing tumour activity.
Typical UK reference range: usually <37 U/mL (ranges may vary by laboratory).

Normal Levels

Normal results indicate expected antigen levels in the bloodstream.
This reduces the likelihood of active disease but does not completely exclude malignancy.

High Levels

Elevated CA 19-9 levels may indicate pancreatic or gastrointestinal cancer.
Levels can also rise in benign conditions such as bile duct obstruction or pancreatitis.
Results must always be interpreted alongside imaging and clinical findings.