CA 19-9 Blood Test (Cancer Antigen) for Pancreatic Cancer : Normal Range & Uses

According to the World Cancer Research Fund (WCRF) International, pancreatic cancer is the 12th most commonly occurring cancer worldwide. Around 10% of individuals who receive an early diagnosis and treatment become disease-free. Doctors may prescribe tests like imaging, ultrasound, angiography or biopsy to detect pancreatic cancer. Among blood tests, the cancer antigen or CA 19-9 test measures the serum cancer antigen 19-9 levels and demonstrates the efficacy of the ongoing treatment. This article tells you more about this test and its usefulness in diagnosing and treating pancreatic cancer.

Meaning of Elevated CA 19-9 Levels

Cancer antigen 19-9 or carbohydrate antigen 19-9 (CA 19-9) is a protein found in the blood. When detected in high quantities, it acts as a tumour marker. Higher than typical amounts of CA 19-9 in the bloodstream indicate the possibility of cancer in the pancreas, colon, stomach, and bile duct.

Who Needs to Undergo a CA 19-9 Blood Test?

A CA 19-9 blood test is not only a diagnostic test for pancreatic cancer but also an indicator of how well the treatment is working. Doctors usually prescribe this blood test for:

• Individuals diagnosed with tumours associated with high levels of serum cancer antigen 19-9 in their bloodstream

• People at a high risk of developing pancreatic and colon cancers

• Individuals with a family history of the condition

• People living with diabetes and hepatitis B

Is CA 19-9 a Reliable Biomarker For Pancreatic Cancer?

Biomarkers are biomolecules in your body that indicate the presence or absence of a biological condition. These biomarkers may be present in the tissues, body fluids or bloodstream. The serum cancer antigen 19-9 is the only validated and clinically useful biomarker in the detection of pancreatic cancer till now. It has a sensitivity of 79-81% for diagnosing pancreatic cancer. This tumour marker is instrumental in designing a prognosis and predicting the overall survival rate of an individual with pancreatic cancer.

Preparing For CA 19-9 Blood Test

Although there are no special requirements for the CA 19-9 blood test preparation, keep the following things in mind:

• Inform your doctor about any medications you are consuming.

• Intimate your doctor regarding any allergies you may have.

• If there has been an incident of an animal bite, inform your doctor about it. Antibodies would be present in your body because of the incident that may interfere with the test results.

• Avoid taking multivitamins or dietary supplements containing biotin (vitamin B7) at least 12 hours before the test to prevent false positive results.

Procedure of CA 19-9 Blood Test

The steps involved during the test are similar to a standard blood test.

• An elastic band tied around your upper arm exposes the veins.

• Clean the insertion site using an antiseptic.

• Draw the blood by inserting a needle into the vein.

• Collect the blood sample in a vial and send it to the laboratory for testing.

The lab technicians conduct a radioimmunoassay (RIA) of the blood sample. They add paramagnetic particles, a protein-buffered solution and monoclonal conjugates to the reaction vessel along with your blood sample. The reaction vessel goes through incubation to separate the materials in the presence of a magnetic field. Then, they add a chemiluminescent substrate. The light emitted is measured with the help of a luminometer. The concentration of CA 19-9 is proportional to the amount of light produced. These steps explain how the serum cancer antigen 19-9 levels are detected. The entire procedure usually takes place in a day.

Associated Risks

Drawing a blood sample for the CA 19-9 blood test takes about 5-10 minutes. There are no substantial risks associated with this test, except may be slight bruising or pain at the spot of the needle insertion. A small percentage of individuals may experience nausea, dizziness or sweating during the test. However, these symptoms subside soon.

Uses of a CA 19-9 Blood Test

The CA 19-9 blood test should not be considered exclusively as a screening test for pancreatic cancer, though it is essential in its diagnosis. This test finds more applications in the management of the condition. The uses of this test are enumerated below: 

• Clubbed with imaging and biopsy tests, it helps detect pancreatic or digestive cancers.

• It helps in monitoring the progress of pancreatic cancer. Increased or decreased levels of the serum cancer antigen 19-9 in the bloodstream indicate the spread or shrinkage of the tumour.

• It gives a fair idea of how the current treatment plan is working.

• It assesses if a relapse has occurred post-treatment.

• It is a part of follow-up care and prognosis for pancreatic cancer.

Interpreting The Results of a CA 19-9 Blood Test

The standard range of CA 19-9 in the blood is 0 to 37 U/ml (units/millilitre). Higher levels than this range do not always indicate pancreatic or digestive cancers. It may even be a marker for non-cancerous conditions such as jaundice, cirrhosis, gallstones, infected bile ducts or pancreatitis. Therefore, this test is not considered a screening test for cancer. But for people already diagnosed with pancreatic cancer or undergoing cancer therapy, periodic checking of CA 19-9 levels indicates how well the body can manage the condition and respond to the treatment. The chart given below depicts how to interpret the results over time.

Conclusion

Although CA 19-9 is one of the most effective biomarkers for pancreatic cancer, its diagnosis should follow additional tests for confirmation. Doctors will never initiate chemotherapy without conclusive evidence. Monitoring the CA 19-9 levels in an individual diagnosed with pancreatic cancer indicates the progression or recurrence of the disease. It can also judge the effectiveness of the current treatment plan. For further information and in-depth details about the CA 19-9 blood test for pancreatic cancer, contact us at Metropolis Healthcare Ltd.