Chronic Myeloid Leukemia (CML): Introduction 

What is cancer?

Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body doesn't need them any longer. Cancer starts when cells in the body change and grow out of control. Abnormal cells grow even though your body doesn’t need them. In most types of cancer, the abnormal cells grow to form a lump or mass called a tumor.

What is leukemia?

Leukemia is different from most other types of cancer. Leukemia is cancer that starts in the bone marrow. This is where new blood cells are made. Leukemia cells are early forms of blood cells, most often white blood cells. When a person has leukemia, the body makes too many abnormal blood cells. Leukemia cells don't often form tumors. But they can travel with the blood all over the body. That means leukemia can affect organs anywhere in the body.

Two types of blood-forming cells can turn into leukemia:

• Lymphoid cells (lymphocytes). This is called lymphocytic leukemia.

• Myeloid cells (myelocytes). This is called myeloid or myelogenous leukemia.

Leukemia can also be either acute or chronic. Acute leukemia grows quickly and needs to be treated right away. Chronic leukemia grows more slowly.

What is chronic myeloid leukemia (CML)?

Chronic myeloid leukemia (CML) is a type of leukemia that starts in myeloid cells in the bone marrow.  It’s also called chronic myelogenous leukemia. It starts in white blood cells that normally help the body fight infections.

There is a change in a chromosome in the cells of almost all people with CML. The change is called the Philadelphia chromosome. It creates an abnormal gene called BCR-ABL. This gene causes the leukemia cells to grow out of control.

As the leukemia cells grow, they can crowd out the normal cells in the bone marrow. This can lead to not having enough of the different types of blood cells in the blood. People with CML have too many abnormal white blood cells in their blood.

CML is a type of chronic leukemia. This means it tends to grow slowly. In most cases CML doesn't cause symptoms right away. But symptoms can develop slowly and get worse over time. Some people with CML have no symptoms when CML is diagnosed. In fact, CML is often diagnosed when a high white blood cell count is found while doing blood tests for another reason.

Talk with your healthcare provider

If you have questions about CML, talk with your healthcare provider. Your provider can help you understand more about this type of leukemia.