Cytogenetic Testing and CCyR

The diagnosis of Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML) is confirmed with cytogenetic testing to detect the Philadelphia chromosome in your bone marrow and blood cells. An important treatment goal is to reduce those cells to undetectable levels. Your doctor will be checking your blood or your marrow (or both) throughout your treatment—with the objective of reaching the point where there are so few of these Ph+ cells that they're undetectable. This is what's known as a complete cytogenetic
response (CCyR)

Cytogenetic Testing: Looking for Philadelphia Chromosomes

Cytogenetic testing specifically measures the number of cells in your blood or bone marrow with the Philadelphia chromosome. The lower the percentage of Philadelphia positive (Ph+) cells, the better your CML is responding to treatment. You and your doctor will pay careful attention to how your responses progress once you begin treatment.

Known as Why it's used
Bone marrow biopsy A way to collect bone marrow cells for counting the leukemic Ph+ cells. (Sometimes fluid is also collected. This is called a bone marrow aspiration.)
Conventional cytogenetic testing A test that uses a bone marrow sample to count the number of cells with the Ph chromosome; it is not very sensitive.
FISH (Fluorescence In Situ Hybridization) A sensitive test on bone marrow or blood that can determine the percentage of your cells that are leukemic.

What do my cytogenetic test results mean?

In people newly diagnosed with CML, the general goals are to reach a complete cytogenetic response (CCyR) by 12 months after starting treatment to eventually achieve a major molecular response (MMR),and to prevent the progression of the disease to accelerated or blast phase.

Cytogenetic test results can also help your doctor understand how you may respond to treatment over time.

Testing your bone marrow or blood using FISH may show 0% Ph+ cells. But this doesn't mean you have no Ph+ cells, and it doesn't mean your CML is cured. You may have minimal disease. Your doctor has a still more sensitive type of test—molecular testing—that can spot leukemic cells by identifying something even smaller than the Ph+ chromosome.

Watching for change in your percentage of Ph+ cells

This chart can help you understand how well your treatment is working. CML treatment results are based on the percentage of cells with the Philadelphia chromosome detected during cytogenetic testing. Find the percentage of Ph+ cells in your test reports, and the corresponding treatment result will be to the right in the chart below.

Number of Philadelphia chromosome-positive (Ph+) cells:
This Percentage of Ph+ Cells Means This Result
0% to 35% Major cytogenetic response (MCyR) combines both CCyR (0%) and PCyR (1% to 35%)
36% to 65% Minor cytogenetic response
66% to 95% Minimal cytogenetic response
More than 95% No cytogenetic response

Record all your test results

If you don't already, make it a habit to ask your doctor for a printout of your test results, so you can enter them in the CML Treatment Companion™ on your computer.

This Web site is not meant to replace a discussion with your doctor, who is your most important source for information.

All individuals depicted in this Web site are models being used for illustrative purposes only. MyCMLCare, "Get the strength that comes from knowledge", CML Treatment Companion, and CML Currents are registered trademarks of Bristol-Myers Squibb Company.