Chronic Myelogenous Leukemia

What is chronic myelogenous leukemia?

Chronic myelogenous leukemia (CML) is a life-threatening cancer that starts in the bone marrow. When you have CML, the bone marrow makes too many white blood cells (myelocyte types). Too many of these cells in the marrow can keep normal blood cells from being made.

Another name for this type of leukemia is chronic myeloid leukemia.

CML is seen mainly in people who are55 to 65 years old.

How does it occur?

Blood cells grow in the bone marrow from blood-forming stem cells. Marrow is the soft, fatty tissue inside the outer, hard part of bones. In CML, the body tells too many bone marrow stem cells to develop into a type of white blood cells called granulocytes. Some of the stem ("mother") cells never become mature white blood cells. Some of these immature cells are called myeloblasts ("blasts"). Over time, the excess granulocytes and blasts crowd out healthy white blood cells, red blood cells, and the cells that make platelets (called megakaryocytes). This may result in infection, anemia, and easy bleeding and bruising.

Most people who have CML have an abnormal stem cell chromosome called the Philadelphia chromosome (Ph+). Chromosomes contain the genetic material (DNA) that determines how cells look and act. The Philadelphia chromosome is not passed from parent to child. The problem is that a gene from one chromosome has moved to another chromosome, and that gene has combined with another gene to make a new gene. This change causes the gene in the stem cells in the bone marrow to make an enzyme called tyrosine kinase. This enzyme causes too many stem cells to develop into white blood cells. Usually it is not known why the chromosome change happens.

The disease has 3 phases:

• chronic phase, which lasts 3 to 5 or more years
• accelerated phase, which lasts 1 to 2 years
• blastic phase, which lasts 3 to 6 months.

The number of blast cells in the blood and bone marrow and the severity of symptoms help determine the phase of the disease. With tests and frequent checkups, your healthcare provider can know what phase of the disease you are having.

What are the symptoms?

Symptoms are usually mild at first and get worse gradually. They may include:

• feeling very tired
• unexplained weight loss
• sweating at night
• fever
• a sense of fullness or pain below the ribs on the left side, caused by an enlarged spleen.

Some people have no symptoms, especially early in the disease.

How is it diagnosed?

Your healthcare provider may discover the disease during a routine blood test. Or your provider may find that you have an enlarged spleen during a physical exam.

Blood tests that may be used to diagnose leukemia are:

• complete blood count (CBC)
• leukocyte alkaline phosphatase.

A sample of your blood or bone marrow will be tested in the lab to look for the Philadelphia chromosome.

A sample of your bone marrow will be taken. In this procedure called a biopsy, a small sample of bone marrow is taken from the hipbone in back and examined under a microscope. Your healthcare provider will get the sample by first numbing the area over the bone. Then a needle will be inserted to suction the sample into a syringe. Usually the biopsy can be done in your provider's office.

How is it treated?

Treatments that may be used to treat CML are:

• Targeted therapy: An oral drug called imatinib is given to try to give you a normal blood count. It works by inactivating the tyrosine kinase enzyme. It can be effective for years. However, after a while CML almost always becomes resistant to imatinib. Other oral drugs, such as busulfan and hydroxyurea, and interferon-alpha injections, have worked in the past. However, imatinib is much more effective.
• When the disease no longer responds to imatinib (something that happens often), a similar oral drug, dasatinib, may be effective.
• High-dose chemotherapy with stem cell transplant: Blood-forming cells are destroyed with high doses of drugs. The cells are then replaced with healthy stem cells removed from a compatible donor's blood or bone marrow.

With treatment, most people in the chronic phase of CML have no symptoms from the disease. You will need to take medicine regularly to keep your white blood cell count normal, or you may need medicine only part of the time. Your healthcare provider will watch your condition and your blood cell count closely. You will have blood tests to make sure the medicine is working.

How long will the effects last?

Medicine can produce a remission, which means your symptoms go away for a while. A remission helps many people live a relatively normal life for some years. However, only a transplant can cure the disease, but this treatment is very difficult. Sometimes the transplant is not successful, and in rare cases it can be fatal.

How can I take care of myself?

• Follow your healthcare provider's recommendations for treatment.
• Eat a healthy diet.
• Get plenty of rest and regular exercise according to your provider's recommendations.
• Ask your provider before you take any medicine, including nonprescription drugs or natural remedies.
• Discuss questions and concerns with your provider.

How can I help prevent chronic myelogenous leukemia?

The cause of CML is not well understood, and no risk factors have been found, so doctors do not know how to prevent it.