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All About Leukemia at Winship Cancer Institute

Introduction to Leukemia

Leukemia is a cancer of the blood-forming cells. When leukemia develops, the body produces large numbers of abnormal blood cells that appear and behave differently from normal blood cells. To better understand what happens when you have leukemia, it is helpful first to know about normal blood.

Normal Blood:

The blood has two components: a liquid part called plasma, and a cellular part or the blood cells. There are three major types of blood cells: red blood cells (RBCs), white blood cells (WBCs), and platelets. All these cells are produced in the bone marrow (soft tissue inside the bones).

  • The role of the RBCs is to carry oxygen throughout the body to different tissues. The percentage of RBCs in the blood is called the hematocrit. The part of the RBC that carries oxygen is a protein called hemoglobin. Anemia occurs when there is a decrease in the number of RBCs in the body and is detected by a low hemoglobin level or a low hematocrit. A normal hemoglobin level ranges between 12 and 16 g/dl ( or a hematocrit of 40-50%). Most people will have some symptoms when the hemoglobin is less than 8. This is why blood transfusions are frequently ordered when the hemoglobin is less than 8.
  • The role of the WBCs is to defend the body against infections. The neutrophils (one subtype of WBCs) kill most regular bacteria. Lymphocytes are responsible for killing viruses and constitute an important part of the immune system. Infections are therefore more likely to occur when the WBCs is low. Normal WBC count is 3,000 to 9,000/mm3. The Absolute Neutrophil Count (ANC) is used to measure the amount of neutrophils you have to fight infections. A patient's ANC is computed by multiplying the total number of WBCs by the percentage of neutrophils. Serious infections are more likely to occur when your ANC falls below 500. A patient's WBC will generally fall within the first week after starting chemotherapy. However, most people recover their WBC count between days 21 to 28 after starting chemotherapy.
  • Platelets are the cells that help control bleeding. The normal platelet count is 150,000- 300,000/mm3. The risk of bleeding increases when the platelet count is less than 10,000-20,000. Platelets transfusion are usually administered when the platelet count is lower than 10-20,000/mm3. The risk of bleeding increases if you have taken aspirin, Motrin or other anti-inflammatory drugs, but Tylenol has no effect on platelets.

Types of Leukemia

Leukemias are classified by the type of cell affected and by the rate of cell growth. Leukemia may be either acute or chronic. Acute leukemia involves a rapid growth of very immature blood cells and is a life-threatening condition requiring immediate treatment. Chronic leukemia involves the growth of more mature blood cells, and usually, does not require immediate treatment. However, some chronic leukemias, such as chronic myeloid leukemia, do progress to a form of acute leukemia. Myelodysplastic Syndrome (MDS) or pre-leukemia is a condition in which the bone marrow does not produce enough normal blood cells, and precedes the development of acute leukemia.

The most common types of leukemia are:

  • Acute lymphocytic leukemia (ALL); the most common type of leukemia in children
  • Acute myeloid leukemia (AML); the most common type of acute leukemia in adults
  • Chronic lymphocytic leukemia (CLL); the most common type of leukemia in adults
  • Chronic myeloid leukemia (CML)

Tissue Bank for Hematologic Disorders