Chronic Granulocytic Leukemia

Alternative names

What is Chronic Granulocytic Leukemia ?

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 middle­aged 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 (beast 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 of Chronic Granulocytic Leukemia

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 that an unidentified virus causes this leukemia.

Signs & Symptoms of Chronic Granulocytic Leukemia

Early in the disease, there may be no noticeable symptoms. The following are the most common symptoms of chronic lymphocytic leukemia. However, each individual may experience symptoms differently. Symptoms may include:

• persistent weakness
• swollen lymph nodes
• enlarged spleen
• enlarged liver
• anemia

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

Diagnostic Tests

Chromosomal studies of peripheral blood or bone marrow showing the Philadelphia chromosome and low leukocyte alkaline phosphatase levels confirm chronic granulocytic leukemia.

Serum analysis shows white blood cell (WBC) abnormalities: leukocytosis (WBC count over 50,OOO/mm3,rising as high as 250,OOO/mm3); occasionally leukopenia (WBC count under 5,OOO/mm3); neutropenia (neutrophil count under 1 ,500/mm3) despite high WBC count; and increased circulating myeloblasts.

Additional findings may include a decreased hemoglobin level (below 10 g/dl), low hematocrit (less than 30%), and thrombocytosis (more than 1 million thrombocytes/mm3). The serum uric acid level may exceed 8 mg/dl.

Treatment

In the chronic phase, treatment strives to controlleukocytosis 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.

Prevention Tips

Avoid exposure to radiation when possible.