Leukemia: Introduction

What is cancer?


Leukemia is different from most other cancers. Leukemia is cancer that starts in the bone marrow. The bone marrow is where new blood cells are made. Leukemia cells are early forms of blood cells. They are usually white blood cells, which normally help fight infections. When your have leukemia, your body makes too many blood cells, and they aren't normal. Leukemia cells do not usually form tumors, but they can travel with the blood all over the body. That means they can reach almost any organ. So leukemia can be present in many different ways, depending on which organs are involved.

Anatomy of  a bone, showing blood cells

What are normal blood cells?




  3. Platelets help form blood clots and control bleeding.



What are leukemia cells?

When a person has leukemia, the body makes too many blood cells of one type. These abnormal cells, usually white blood cells, look different from normal blood cells. They don't work as they should. They also interfere with the making of other blood cells, usually red blood cells and platelets.

Types of leukemia


Leukemia is grouped in two ways:

  1. Acute or chronic, depending on how fast the cells grow

  2. Lymphocytic or myeloid, depending on the type of white blood cell that has turned into leukemia

In acute leukemia, the abnormal blood cells are usually young cells (immature blasts) that do not work as they should properly. These cells grow quickly. Acute leukemia quickly gets worse unless it is treated right away.

In chronic leukemia, young blood cells are present, but mature, functional cells are also made. In chronic leukemia, blasts grow slowly. It takes longer for the disease to get worse.



  • Acute myeloid leukemia (AML). AML is one of the most common types of acute leukemia in adults. AML can also occur in children. In children, it makes up about 1 in 4 leukemias.

