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Types of Cancer - Leukemia

Leukemia is a cancer of the blood cells that occurs when certain blood cells become abnormal and are produced in unnaturally large numbers.

Types of Cancer

What is Leukemia?

Blood cells are produced in the bone marrow, the soft, spongy center of bones. New (immature) blood cells are called blasts. Some blasts stay in the marrow to mature. Some travel to other parts of the body to mature. Normally, blood cells are produced in an orderly, controlled way, as the body needs them. This process helps keep us healthy.

When leukemia develops, the body produces large numbers of abnormal blood cells. In most kinds of leukemia, the abnormal cells are white blood cells, the cells which normally help the body stave off infection and disease. The leukemia cells often have a different appearance from normal blood cells, and they do not function properly.

Types of Leukemia

Leukemia can be classified in two ways. One way is by the rate at which the disease develops and worsens; leukemia which progresses quickly is called acute leukemia, while slower progressing leukemia is termed chronic leukemia. In chronic leukemia, some blast cells (immature blood cells) are present, but in general the affected cells are more mature and can carry out some of their normal functions. The number of blasts, and thus the disease, increases at a relatively slow pace. In acute leukemia, the abnormal blood cells are blasts that remain very immature and cannot carry out their normal functions. The number of blasts increases rapidly, and the disease gets worse quickly.

Leukemia can also be classified according to the type of blood cells affected. There are two main categories of blood cells which can turn into leukemia: lymphoid cells and myeloid cells. When leukemia affects lymphoid cells, it is called lymphocytic leukemia. When myeloid cells are affected, the disease is called myeloid or myelogenous leukemia. These are the most common types of leukemia:

Acute Lymphocytic Leukemia (ALL)

The most common type of leukemia in young children. This disease also affects adults, especially those age 65 and older.

Acute Myeloid Leukemia (AML)

Occurs in both adults and children. This type of leukemia is sometimes called acute nonlymphocytic leukemia (ANLL).

Chronic Lymphocytic Leukemia (CLL)

Most often affects adults over the age of 55. It sometimes occurs in younger adults, but it almost never affects children.

Chronic Myeloid Leukemia (CML)

Occurs mainly in adults. A very small number of children also develop this disease.

Treatment

Treatment for leukemia is complex. It varies with the type of leukemia and is not the same for all patients. The doctor plans the treatment to fit each patient's needs. The treatment depends not only on the type of leukemia, but also on certain features of the leukemia cells, the extent of the disease, and whether the leukemia has been treated before. It also depends on the patient's age, symptoms, and general health.

Acute leukemia needs to be treated right away. The goal of treatment is to bring about remission. Then, when there is no evidence of the disease, more therapy may be given to prevent a relapse. Many people with acute leukemia can be cured.

Chronic leukemia patients who do not have symptoms may not require immediate treatment. However, they should have frequent checkups so the doctor can see whether the disease is progressing. When treatment is needed, it can often control the disease and its symptoms. However, chronic leukemia can seldom be cured.

Most patients with leukemia are treated with chemotherapy. Some also may have radiation therapy and/or bone marrow transplantation (BMT) or biological therapy. In some cases, surgery to remove the spleen (an operation called a splenectomy) may be part of the treatment plan. For more information on these types of treatments, please check out the Treatments section of the web site.

Many patients and their families want to learn all they can about leukemia and the treatment choices so they can take an active part in decisions about medical care. The doctor is the best person to answer these questions. When discussing treatment, the patient (or, in the case of a child, the patient's family) may want to talk with the doctor about research studies of new treatment methods. Such studies, called clinical trials, are designed to improve cancer treatment. More information about clinical trials is in the Clinical Trials section.

Researchers are finding better ways to treat leukemia, and the chances of recovery keep improving. Still, it is natural for patients and their families to be concerned about the future. There are many resources available both on and off the web for patients and their families. Links to some good web sites can be found on our web resources page, or check out our recommended reading list for patients and their families.

Source: NCI Cancernet