Chronic Myelocytic Leukemia

Introduction

Chronic myelocytic leukemia (CML) may affect people of any age and of either sex, but is uncommon in children younger than 10 years. The disease most commonly develops in adults between the ages of 40 and 60. The cause usually is a rearrangement of two particular chromosomes into what is called the Philadelphia chromosome. The Philadelphia chromosome produces an abnormal enzyme (tyrosine kinase), which is responsible for the abnormal growth pattern of the white blood cells.

In CML, most of the leukemia cells are produced in the bone marrow, but some are produced in the spleen and liver. In contrast to the acute leukemias, in which large numbers of immature white blood cells are present, the chronic stage of CML is characterized by marked increases in the numbers of normal-appearing white blood cells and sometimes platelets. During the course of the disease, more and more leukemia cells fill the bone marrow and others enter the bloodstream.

Symptoms

Eventually the leukemia cells undergo more changes, and the disease progresses to an accelerated phase and then inevitably to blast crisis. Massive enlargement of the spleen is common in blast crisis, as well as fever and weight loss. Symptoms and Diagnosis Early on, in its chronic stage, CML may produce no symptoms. However, some people become fatigued and weak, lose their appetite, lose weight, develop a fever or night sweats, and notice a sensation of being full—which is usually caused by an enlarged spleen. As the disease progresses to blast crisis, people become sicker because the number of red blood cells and platelets decreases, leading to paleness, bruising, and bleeding.

Diagnosis

• The diagnosis of CML is suspected based on the results of a simple blood test. The test may show an abnormally high white blood cell count. In blood samples examined under a microscope, less mature white blood cells, normally found only in bone marrow, are seen.
• Tests that analyze chromosomes (cytogenetics or molecular genetics) are needed to confirm the diagnosis by detecting the Philadelphia chromosome Prognosis and Treatment

Treatment

• Although most treatments do not cure the disease, they do slow its progress. Newer drugs block the abnormal enzyme produced by the Philadelphia chromosome. These drugs are more effective than other treatments and cause only minor side effects.
• Survival is over 90% at 5 years past diagnosis.
• Stem cell transplantation combined with high doses of chemotherapy drugs may cure CML. However, only certain people can have transplantation. Stem cells must come from a donor who has a compatible tissue type, usually a sibling.
• Transplantation is most effective during the early stage of the disease and is considerably less effective if the CML is rapidly progressing or there is a blast crisis.
• People in a blast crisis live only a few months without treatment. Treatment, chemotherapy drugs sometimes extends survival to 12 months or more.
• There are also older chemotherapy regimens that can be given to people who relapse who have CML without a Philadelphia chromosome., None of the drugs prolongs survival but, they may help relieve symptoms.), which is responsible for the abnormal growth pattern of the white blood cells in CML.

Source: Portal Content Team