BCR-ABL Testing: Quick Guide for Patients and Caregivers

If a doctor mentions BCR-ABL testing, they’re talking about a blood test that looks for a specific genetic change linked to chronic myeloid leukemia (CML) and some other blood cancers. This tiny piece of DNA, called the BCR-ABL fusion gene, tells doctors two things: whether you have the disease and how well your treatment is working.

Why does it matter? Almost every CML case has this gene, so spotting it early can save lives. Plus, newer medicines target the BCR-ABL protein, so the test also helps doctors decide if a drug is doing its job or if you need a change.

When to Get Tested

Usually, you’ll have a BCR-ABL test if you:

• Show symptoms like fatigue, night sweats, or an enlarged spleen.
• Have an abnormal white‑blood‑cell count on a routine blood work.
• Are already diagnosed with CML and need to track the disease.

If you’re on a BCR‑ABL inhibitor (like imatinib or dasatinib), doctors will repeat the test every few months. The goal is to catch any rise in the gene level before symptoms flare up.

How the Test Is Done

The most common method is a quantitative PCR (polymerase chain reaction). A nurse draws a small amount of blood, sends it to a specialized lab, and the lab amplifies any BCR‑ABL DNA it finds. The result is a number that shows how many BCR‑ABL copies are in your blood compared to a normal reference gene.

Some labs also use FISH (fluorescence in‑situ hybridization) or next‑generation sequencing for a more detailed look, especially if the PCR result is unclear.

Getting the sample is quick—just a routine blood draw. The lab usually returns results within a week, and your doctor will explain what the numbers mean. A low level (often called a “major molecular response”) means the treatment is holding the disease in check. A higher level may signal that the cancer is coming back or that the drug isn’t hitting the target.

It’s normal to feel anxious waiting for results. Ask your doctor to walk you through the report so you know exactly where you stand. If the test shows a jump in BCR‑ABL, don’t panic—there are several next‑step options, from tweaking the dose to switching to a different medication.

Remember, BCR‑ABL testing is just one piece of the puzzle. Your doctor will also look at blood counts, bone‑marrow exams, and how you feel day‑to‑day. Combining all that info helps build a clear picture of your health.

Bottom line: the test is fast, minimally invasive, and a powerful tool for both diagnosing CML and keeping it under control. If you’re scheduled for a BCR‑ABL test, brace yourself for a simple blood draw, a short wait for results, and then a conversation that can guide your treatment plan.