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Doctor K: Leukemia affects blood cells

Thu., Feb. 7, 2013, midnight

DEAR DOCTOR K: My uncle was recently diagnosed with leukemia. I’d like to learn more about it.

DEAR READER: Leukemia is a form of cancer that affects the body’s blood cells. Almost every type of cell in our body can turn cancerous, and blood cells are no exception.

Every day, each of us makes millions of new blood cells – red blood cells, white blood cells, and the cells that make platelets (little cell fragments that help blood to clot). Blood cells are made in the marrow (the inside) of bones.

Blood cells have a relatively short life. Red blood cells last about 120 days. That’s why we need to make so many new cells every day. However, when a cell turns cancerous, it doesn’t die. As a result, the number of cells in the bone marrow and in the blood start increasing.

The most common types of leukemia involve one of the two major types of white blood cells: lymphocytes and myelocytes. These cells help the immune system fight off viruses, infections and other invading organisms.

Leukemias arising from lymphocytes are called lymphocytic leukemias. Those arising from myelocytes are called myeloid, or myelogenous, leukemias. Leukemia is either acute (comes on suddenly) or chronic (lasts a long time). There are four major types of leukemia:

• acute lymphocytic leukemia (ALL)

• acute myeloid leukemia (AML)

• chronic lymphocytic leukemia (CLL)

• chronic myeloid leukemia (CML)

Leukemia treatments – chemotherapy and radiotherapy – target the cancerous cells being produced in bone marrow. Unfortunately, the treatment kills some healthy blood cells along with the cancerous cells. As a result, treatment often severely compromises the body’s ability to fight infection.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.

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