Leukemias are cancers of white blood cells or of cells that develop into white blood cells. Leukemias are grouped into 4 types---acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, and chronic myeloid leukemia---according to how quickly they progress and the type of cell involved.
Leukemias are cancers of white blood cells or of cells that develop into white blood cells. White blood cells (also called leukocytes) develop from stem cells in the bone marrow. The 5 main types of white blood cells are neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
Sometimes white blood cells do not develop correctly, resulting in abnormal cell division. When abnormal cell division occurs, cells multiply uncontrollably and become cancerous, resulting in leukemia. Leukemia cells ultimately occupy bone marrow and circulate through the blood stream. These cells can also invade other organs, including the liver, spleen, lymph nodes, testes, and brain.
Leukemias are grouped into 4 main types, according to how quickly they progress and the type of cell that becomes cancerous. The 4 types of leukemia are acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, and chronic myelocytic leukemia. Lymphocytic leukemias are leukemias in which cancer cells replace cells that would normally develop into lymphocytes in the bone marrow and blood. Myeloid leukemias are leukemias in which cancer cells resemble cells that would normally develop into myelocytes. In acute leukemias, cancer cells multiply rapidly. In chronic leukemias, cancer cells multiply more slowly.
Acute lymphocytic leukemia is the most common cancer among children, most often affecting children between ages 2 and 5 years. Acute myeloid leukemia is the most common leukemia among adults, although it affects people of all ages. Chronic lymphocytic leukemia most commonly affects the elderly: About 75% of people with chronic lymphocytic leukemia are older than 60. Chronic myeloid leukemia most commonly occurs among adults between ages 40 and 60.
Many leukemias can be treated effectively. When leukemia is under control, the disease is said to be in remission.
