BCR-ABL1 Genetic Test

Why this test may be ordered

• To diagnose or rule out chronic myeloid leukemia (CML)
• To diagnose or rule out Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL)
• To help plan treatment for blood cancers that involve BCR-ABL1
• To see if cancer treatment is working
• To monitor for cancer recurrence after treatment

Preparation and collection

You usually do not need any special preparations for a blood test. If you are having a bone marrow test, your provider will tell you whether you need to fast (not eat or drink) for a few hours before the procedure.

For a blood test, a health care professional will take a blood sample from a vein in your arm using a small needle. For a bone marrow test, a sample is usually taken from the back of the hip bone after numbing the area; it involves a bone marrow aspiration and a bone marrow biopsy.

There is very little risk to having a blood test; you may have slight pain or bruising at the needle site. After a bone marrow test, you may feel stiff or sore where the sample was taken, which usually goes away in a few days.

Understanding results

Results from BCR-ABL1 genetic testing are interpreted along with other test results and clinical information. For diagnosis, the presence of abnormal white blood cells, the BCR-ABL1 gene, and the Philadelphia chromosome together indicate a diagnosis of chronic myeloid leukemia (CML) or Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL). For treatment monitoring, your provider will compare your current BCR-ABL1 level with previous results. A decrease suggests treatment is working; an increase may indicate treatment failure or cancer recurrence.

• BCR-ABL1 gene detected (positive): Suggests the presence of CML or Ph+ ALL when combined with other abnormal findings. Limitation: A positive result by itself does not confirm leukemia; it must be interpreted with blood cell counts and other tests. Next step: Your provider will correlate with other laboratory and clinical findings to make a diagnosis.
• BCR-ABL1 gene not detected (negative): No abnormal BCR-ABL1 gene found; makes CML or Ph+ ALL less likely. Limitation: A negative result does not completely rule out these leukemias, as rare cases may not have the Philadelphia chromosome. Next step: Your provider will consider other causes for your symptoms if they persist.
• Decreased BCR-ABL1 level (during treatment): Treatment is working to some degree. Limitation: The meaning depends on the specific test method and comparison with prior results. Different labs may use different methods. Next step: Continue current treatment and monitoring as recommended by your provider.
• Increased BCR-ABL1 level (during or after treatment): Treatment may not be working, or cancer may have returned. Limitation: An increase alone does not confirm recurrence; further evaluation is needed. Next step: Discuss with your provider; you may need alternative treatment or additional tests.

• Different laboratory methods may yield different results. It is important to have tests done consistently in the same lab for accurate monitoring.
• A negative BCR-ABL1 result does not completely exclude CML or Ph+ ALL, as rare cases may lack the Philadelphia chromosome.
• This test is not diagnostic on its own; it must be interpreted alongside other laboratory and clinical findings.

What to do next

Your healthcare provider will review your results in the context of your overall health. Depending on the results, further testing may be needed. If diagnosed, treatment options include targeted therapies. Regular monitoring with BCR-ABL1 testing is often used to assess treatment response and detect recurrence.

• What does my BCR-ABL1 test result mean?
• How often will I need this test?
• What is the difference between a blood test and a bone marrow test for this test?
• Can I pass the BCR-ABL1 gene change to my children?

Evidence source

U.S. National Library of Medicine: BCR-ABL1 Genetic Test