Chronic Granulocytic Leukemia

Alternative names :- CML; Chronic myelogenous leukemia ; Leukemia - chronic granulocytic (CML)

Chronic granulocytic leukemia is characterized by the abnormal overgrowth of granulocytic precursors (myeloblasts, promyelocytes, metamyelocytes, and myelocytes) in bone marrow, peripheral blood, and body tissues. It's also called chronic myelogenous (or myelocytic) leukemia.

The disease is most common in young and middle aged adults, slightly more common in men than in women, and rare in children. In the United States, between 3,000 and 4,000 cases of chronic granulocytic leukemia develop annually, accounting for about 20% of all leukemias.

The clinical course of chronic granulocytic leukemia proceeds in two distinct phases: the insidious chronic phase, characterized by anemia and bleeding abnormalities, and eventually the acute phase (bast crisis), in which myeloblasts, the most primitive granulocytic precursors, proliferate rapidly.

The disease is always deadly. Average survival time is 3 to 4 years after onset of the chronic phase and 3 to 6 months after onset of the acute phase

Causes

Although the exact causes remain unknown, almost 90% of patients with this leukemia have the Philadelphia chromosome, an abnormality in which the long arm of chromosome 22 translocates to chromosome 9. Radiation and carcinogenic chemicals may induce this abnormality.

Myeloproliferative diseases also may increase the incidence of chronic granulocytic leukemia. Some researchers suspect [hat an unidentified virus causes this leukemia.

Signs and Symptoms

The following are the most common symptoms of chronic myelogenous leukemia. However, each individual may experience symptoms differently. Symptoms may include:

• anemia
• bleeding
• bruising
• fever
• persistent weakness
• fatigue
• aches in bones and joints
• swollen lymph nodes

The symptoms of chronic myelogenous leukemia may resemble other blood disorders or medical problems. Always consult your physician for a diagnosis.

Diagnostic tests 

In addition to a complete medical history and physical examination, diagnostic procedures for chronic myelogenous leukemia may include:

• A physical examination often reveals an enlarged spleen
• A CBC shows increased white blood cell count
• Bone marrow aspiration and/or biopsy
• The presence of the Philadelphia chromosome

Treatment

In the chronic phase, treatment strives to control leukocytosis and thrombocytosis. Commonly used drugs include busulfan and hydroxyurea. Aspirin may be given to prevent a cerebrovascular accident if the patient's platelet count exceeds 1 million/mm3.

Bone marrow transplantation may be tried. During the chronic phase, more than 60% of patients who receive a transplant achieve remission.

Ancillary treatments may include the following:

• local splenic radiation or splenectomy to increase the platelet count and to decrease adverse effects associated with splenomegaly
• leukapheresis (selective leukocyte removal) to reduce the WBC count
• allopurinol to prevent secondary hyperuricemia or colchicine to relieve gouty attacks caused by elevated serum levels of uric acid
• prompt antibiotic treatment of infections that may result from chemotherapy-induced bone marrow suppression.

During the acute phase of this leukemia, either lymphoblastic or myeloblastic disease may develop. Treatment is similar to that for acute lymphoblastic leukemia. Remission, if achieved, is commonly shortlived.

Despite vigorous treatment, chronic granulocytic leukemia rapidly advances after onset of the acute phase.

Prevention

Avoid exposure to radiation when possible.