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What is CML (Chronic Myeloid Leukemia)?

Chronic myeloid leukemia, also known as chronic myelogenous leukemia and CML, is a cancer of the blood and bone marrow in which the body produces cancerous white blood cells. The bone marrow is the inner part of your bones where blood cells are made. With leukemia, two things happen. First, certain blood cells become abnormal or defective. Second, the body keeps producing large numbers of these abnormal cells.

Chronic means a relatively slower-growing and slow-acting cancer that may take years to progress. Myeloid refers to the type of white blood cell being overproduced – a myeloid cell. When you have CML, your body makes too many abnormal white blood cells (cells that normally fight infection). So, chronic myeloid leukemia (CML) is a slow-acting cancer that makes the body produce too many cancerous myeloid white blood cells.

Inside each cell in your body are chromosomes. Chromosomes hold the blueprint, or directions, for making more cells. When the young white blood cell (WBC) accidentally makes an abnormal chromosome, called the Philadelphia chromosome (abbreviated Ph), then this type of cancer can begin. Almost all patients with CML (95-100%) have this Philadelphia chromosomal abnormality (also referred to as an irregularity or defect). The disease is often referred to as Philadelphia chromosome-positive chronic myeloid leukemia. It is abbreviated as Ph+ CML.

Ph+ CML is a serious condition. If not properly treated, Ph+ CML can be life threatening. But the good news is that Ph+ CML is treatable.

How many people have CML and who gets it?

CML is a rare cancer. Current CML disease statistics:

  • Worldwide, CML has an incidence (rate of occurrence of new cases) of one to two cases per 100,000 people per year
  • CML is responsible for 10 to 15% of all adult cases of leukemia
  • Average age at diagnosis is around 66
  • Over half of cases are diagnosed in people 65 and older
  • CML is slightly more common in men; the reasons for this are unknown
  • CML is rarely seen in children

The American Cancer Society's most recent 2010 estimates for new cases of CML in the United States:

  • About 4,870 new cases of CML projected to be diagnosed (2,800 in men and 2,070 in women)

It is estimated that approximately 24,800 people in the United States are living with CML. This is considered the prevalence of the disease in the United States (total number of cases of disease in a population).

Where do you go to find information about CML?
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