What is Leukemia

Leukemia is cancer of the blood cells. Most blood cells form in the bone marrow. In leukemia, cancerous blood cells form and crowd out the healthy blood cells in the bone marrow.

The type of leukemia depends on the type of blood cell that has become cancerous. For example, acute lymphoblastic leukemia is a cancer of the lymphoblasts (white blood cells that fight infection). White blood cells are the most common type of blood cell to become cancer. But red blood cells (cells that carry oxygen from the lungs to the rest of the body) and platelets (cells that clot the blood) may also become cancer.

Leukemia occurs most often in adults older than 55 years, and it is the most common cancer in children younger than 15 years.

Leukemia is either acute or chronic. Acute leukemia is a fast-growing cancer that usually gets worse quickly. Chronic leukemia is a slower-growing cancer that gets worse slowly over time. The treatment and prognosis for leukemia depend on the type of blood cell affected and whether the leukemia is acute or chronic. Chemotherapy is often used to treat leukemia.

Key Points

• Adult acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell).
• Leukemia may affect red blood cells, white blood cells, and platelets.
• Previous chemotherapy and exposure to radiation may increase the risk of developing ALL.
• Signs and symptoms of adult ALL include fever, feeling tired, and easy bruising or bleeding.
• Tests that examine the blood and bone marrow are used to detect (find) and diagnose adult ALL.
• Certain factors affect prognosis (chance of recovery) and treatment options.
• Adult acute myeloid leukemia (AML) is a type of cancer in which the bone marrow makes abnormal myeloblasts (a type of white blood cell), red blood cells, or platelets.

A Snapshot of Leukemia

Leukemia, the second most common blood cancer after lymphoma, includes several diseases. The four major types are acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), acute myelogenous leukemia (AML), and chronic myelogenous leukemia (CML). Although leukemia occurs most often in older adults, it is among the most common childhood cancers. ALL accounts for approximately 75 percent of all childhood leukemias. By contrast, the most common types of leukemia in adults are AML and CLL, followed by ALL and CML.

The overall incidence rates for leukemia have increased on average 0.2 percent each year from 2002 to 2011, while overall mortality rates have fallen an average of 1 percent each year from 2001 to 2010. Incidence and mortality rates are higher in whites than in people of other racial and ethnic groups. Leukemia is slightly more common in men than women.

Specific risk factors for leukemia depend on the type of leukemia. In general, increased risk is associated with being male, smoking, exposure to certain chemicals such as benzene, exposure to radiation, past treatment with chemotherapy or radiation therapy, having certain inherited or genetic disorders, having certain blood disorders, and having a family history of leukemia. There are no standard screening tests for leukemia. Depending on the type of leukemia, standard treatments include watchful waiting, chemotherapy, targeted therapy, radiation therapy, and stem cell transplant.

Assuming that incidence and survival rates follow recent trends, it is estimated that $5.9 billion1 will be spent on care for patients with leukemia in the United States in 2014.