What Is Leukemia?

Microscopic view of blood cells comparing normal blood and leukemia.Cancer happens when cells in the body begin changing in ways that aren't normal. Cancer that starts in blood cells is called leukemia.

Understanding the blood

Blood is made up of cells and fluid. The body constantly replaces old blood cells with new ones to keep the blood healthy. New blood cells are made in the bone marrow (the spongy substance inside bones). The major types of blood cells are:

  • White blood cells help the body fight off infections and disease.

  • Red blood cells carry oxygen from the lungs to all parts of the body. They also carry carbon dioxide back to the lungs.

  • Platelets help form blood clots and stop bleeding.

When leukemia forms

Leukemia is often a cancer that starts in the white blood cells. When leukemia happens, the body makes many abnormal white blood cells that don't work the way they should. Or the body makes too many immature white blood cells (called blasts) that don't mature into normal white blood cells. In either case, more abnormal than normal cells are made. This can clog up the bone marrow. The blood is then not able to make normal, healthy blood cells.

There are 4 major types of leukemias:

  • Leukemia can be myeloid or lymphocytic. These terms refer to the type of cell that the cancer starts in.

  • Leukemia can be acute or chronic. Acute leukemias get worse very quickly. Chronic leukemias tend to be slow growing. But they may get worse over time.

Treatment choices for leukemia

You and your healthcare provider will decide on a treatment plan that's best for your needs. The main treatments for this cancer are:

  • Chemotherapy, which uses strong medicines to kill cancer cells.

  • Targeted therapy, which uses drugs that attack parts of leukemia cells that make them different from normal cells. 

  • Immunotherapy, which builds up the body's own immune system to help fight cancer. 

  • A stem cell transplant, which removes the tissues or cells that make blood cells and replaces them with healthy tissues or cells.

  • Radiation therapy, which uses strong doses of radiation to help prevent or treat leukemia in certain parts of the body. 

Treatment depends on many factors, such as the type of leukemia you have, your overall health, the availability of a stem cell match, and your preferences.