BCR Blood Test Results Explained


The BCR blood test, which is formally called the BCR-ABL1 test, looks for a specific gene sequence that is found with an abnormal chromosome 22 in some individuals who have certain forms of leukemia. Testing can detect what is called the Ph, or Philadelphia, chromosome and the BCR-ABL1 gene sequence.

There may be several additional tests ordered to detect leukemia in addition to this specific blood test. This includes qualitative and quantitative molecular genetic testing. These results will be used in combination with the BCR blood test to confirm a leukemia diagnosis. Some of the tests are also used to monitor how well someone may be responding to treatment.

Some medical providers may also order the BCR blood test to rule out leukemia as a diagnosis option.

When Is the BCR Blood Test Ordered?

The BCR blood test is ordered whenever a medical provider suspects that someone is suffering from Chronic Lymphocytic Leukemia, which is the most common form of the disease in Western countries. It will also be ordered if the medical provider suspects the issue may be Ph-positive Acute Lymphoblastic Leukemia.

When the disease is present, there may be several bothersome signs and symptoms being experienced. This may include ongoing fatigue, unexpected weight loss, joint or bone pain, and an enlarged spleen. When the disease is in its earliest stages, someone may not have any symptoms whatsoever or they may be so mild that they are ignored. In these circumstances, abnormal findings on a complete blood count may lead toward a diagnosis through follow-up testing.

Depending on the number of abnormal cells that are present, anemia may also be experienced during the early stages of the disease. Prolonged bleeding and recurrent infections may also occur.

Once these forms of leukemia have been diagnosed, the BCR blood test is generally ordered once every 3 months to monitor treatment response or to watch for recurrence.

What Do the Results of the BCR Blood Test Mean?

A positive result from the BCR blood test indicates that the BCR-ABL1 gene sequence is present in their blood. This may or may not be accompanied by detection of the Philadelphia chromosome. In up to 95% of people who are diagnosed with CML, the Philadelphia chromosome is present and 100% will have the gene sequence. About 25% of adults with ALL and up to 4% of children with ALL will also test positive for the chromosome or gene sequence.

In the up to 10% of cases where the gene sequence is present, but not the chromosome, then follow-up testing will need to take place to locate the variant translocations that involve a third or fourth chromosome.

If the test results are initially positive, and then follow-up testing shows reductions to the amount of the gene sequence, then this is an indication that the treatment is effective. Once the gene sequence cannot be detected by the BCR blood test after a positive result, then the individual is considered to be in remission.

Here’s What You Need To Know About the BCR Blood Test

Treatment of leukemia that is detected by the BCR blood test is based on the phase of the disease. There are three phases: the chronic phase, accelerated phase, and blast phase. Most people are diagnosed in the chronic phase because the symptoms of this disease are so subtle. This phase may last for up to several years without detection. This phase is also the easiest to treat from a medical standpoint.

In the accelerated phase, changes to white blood cell counts occur and there may be additional changes to the number of blasts in the blood and bone marrow changes that are less than 20%. People in the accelerated phase may see a lack of response to standard treatments.

The blast phase occurs when 20% or more of the cells in the bone marrow or blood changes or if there is blast proliferation outside of the bone marrow.

Depending on the test results, bone marrow testing may also be required to determine a definitive diagnosis. Most medical professionals will rely on a series of testing results instead of one specific BCR blood test to monitor patient health.

If you have any concerns about the physical signs and symptoms being experienced and are concerned that leukemia may be the cause, then schedule an appointment with your medical provider to discuss this guide. Only a qualified medical professional can interpret test results with your medical history to determine if this disease is present and should be treated.