Types of Leukemia
Leukemia is not one disease, but several— and while they all affect the blood, the treatments are based the specific type of leukemia and how far it's progressed.
Some are more common in children, while others are more common in adults. Some are more aggressive than others. Understanding more about the specific type of leukemia is an important step toward understanding your treatment.
How is Leukemia Classified?
Leukemias are categorized by which type of blood cell they arise from and how quickly they progress.
This category of leukemia develops in the white blood cells called lymphocytes in the bone marrow. Because it affects lymphoid cells it will be referred to as lymphoid, lymphocytic, or lymphoblastic leukemia.
Myeloid cells are the starting point for red blood cells, platelets and other types of white blood cells not generated by lymphocytes. Leukemia that affects myeloid cells is called myeloid, myelogenous, or myeloblastic leukemia.
Leukemia is also categorized by how quickly the leukemia cells grow.
Fast-growing leukemias are called acute. This category of leukemia tends to show more symptoms and will need treatment right away.
Chronic leukemia tends to grow slowly. It doesn't present symptoms right away and may require treatment over many years.
Chronic lymphocytic leukemia (CLL)
CLL, the most common type of leukemia, affects lymphoid cells and usually grows slowly. The people most often diagnosed with the disease are over age 55. While it can be diagnosed in both men and women, it's more common in men. It almost never affects children.
Acute myeloid leukemia (AML)
AML affects both the blood cells and the bone marrow. The bone marrow creates too many immature white blood cells that become cancerous, leaving very few healthy white blood cells for the body to use. This leave the body prone to more infections. AML is more common in older men.
Chronic myeloid leukemia (CML)
CML is caused by a genetic mutation of the Philadelphia chromosome. It affects the blood cells when immature white blood cells form and reproduce uncontrolled. This crowds out all the other types of necessary blood cells.
Acute lymphocytic (lymphoblastic) leukemia (ALL)
ALL affects lymphocytes, causing them to grow too quickly. Two subtypes impact treatment based on whether it's T-cell or B-cell based. ALL is the most common type of leukemia in young children, however, it also affects adults.
Less Common Types of Leukemia
Another type of leukemia is hairy cell leukemia. Hairy cell leukemia is a rare type of leukemia in which abnormal B-lymphocytes (a type of white blood cell) are present in the bone marrow, spleen, and peripheral blood. When viewed under a microscope, these cells appear to be covered with tiny hair-like projections.