Leukemia Types

Different types of leukemia require different types of treatment and affect different age groups. These types of leukemia also have their own expected survival rates. To better understand how different types of leukemia progress, it’s necessary to understand the differences between myeloid and lymphoid cells, and why acute leukemia spreads faster than chronic leukemia.

Acute Leukemia vs. Chronic Leukemia

Acute leukemia occurs due to an overabundance of immature blood cells, called blast cells, or “blasts.” Blasts reproduce quickly, crowding out healthy blood and bone marrow cells. Without treatment, acute leukemia is often fatal within months. Acute types of leukemia are most commonly found in children.

In contrast, chronic leukemia is more common in adults. In chronic leukemia, blast cells are not the offending cells. Instead, the malignant cells mature further, sometimes even resembling normal cells, though they aren’t able to function as healthy white blood cells (WBCs). Chronic types of leukemia progress more slowly than acute leukemia.

Myeloid vs. Lymphoid Leukemia

There are two sets of white blood cells associated with different types of leukemia: myeloid and lymphoid. Lymphoid cells, or lymphocytic cells, are immune system cells. WBCs of the myeloid type include granulocytes that destroy bacteria, and monocytes that fight infections and foreign substances. Types of leukemia are first classified depending on which of these two sets of cells become malignant, and then by the cell subtype.

Leukemia Blood Cells - Types of Leukemia

Acute Myelogenous Leukemia (AML)

Approximately 20 percent of childhood leukemia cases are acute myelogenous leukemia, according to Children’s Hospital Boston (n.d.). The risk of this type of acute leukemia increases with age. The American Cancer Society (2010) reports that approximately 12,330 Americans are diagnosed with acute myelogenous leukemia annually.

Acute Lymphocytic Leukemia (ALL)

While acute lymphocytic leukemia can occur at any age, the Leukemia and Lymphoma Society (2009) reports that it’s most common in children under the age of 15, with this risk increasing after age 45. Acute lymphocytic leukemia is less common than acute myelogenous leukemia, with approximate 5,430 cases diagnosed annually in the United States.

Chronic Myelogenous Leukemia (CML)

Nearly 5,000 Americans are diagnosed with chronic myelogenous leukemia each year, according to the National Cancer Institute (2010). Chronic myelogenous leukemia affects immature granulocytes, halting their development in the blast stage.

CML is easier to identify than other types of leukemia: The Leukemia and Lymphoma Society (2009) reports that over 95 percent of people with chronic myelogenous leukemia carry the Philadelphia chromosome. The Philadelphia chromosome is formed by translocation, which is when genetic material from chromosome 9 swaps places with chromosome 22. This genetic anomaly leads to uncontrolled proliferation and reproduction of white blood cells and platelets.

Chronic Lymphocytic Leukemia (CLL)

CLL is most common in people over the age of 60 and doesn’t affect children, as reported by the Leukemia and Lymphoma Society (2009). Approximately 85,710 Americans live with CML. Among all types of leukemia, chronic lymphocytic leukemia is most commonly diagnosed in the United States.

Abnormal CLL lymphocytes resemble mature cells, and are very long-lived. Instead of rapid reproduction rates, it is these cells’ longevity that allows them to slowly crowd out other blood cells. As a result, this chronic leukemia is one of the slowest progressing forms of blood cancer.

Resources

American Cancer Society. (2010). What are the key statistics about acute myeloid leukemia? Retrieved July 14, 2010, from http://www.cancer.org/Cancer/Leukemia-AcuteMyeloidAML/DetailedGuide/leukemia — acute-myeloid — myelogenous — key-statistics.

Caring for Cancer Staff. (n.d.). Acute myelogenous leukemia center. Retrieved April 27, 2010, from the Caring for Cancer website: http://www.caring4cancer.com/go/aml.

Children’s Hospital Boston Staff. (n.d.). Acute myelogenous leukemia. Retrieved April 27, 2010, from the Children’s Hospital Boston website: http://www.childrenshospital.org/az/Site2168/mainpageS2168P0.html.

Health Communities Staff. (2009). Leukemia: Types. Retrieved March 22, 2010, from the Oncology Channel website: http://www.oncologychannel.com/leukemias/types.shtml.

Leukemia and Lymphoma Society. (2009). Acute lymphocytic leukemia. Retrieved March 22, 2010, from the Leukemia and Lymphoma Society website: www.leukemia-lymphoma.org/all_page?item_id=7049#_ALLsubtypes.

Leukemia and Lymphoma Society Staff. (2009). Acute myelogenous leukemia. Retrieved March 22, 2010, from the Leukemia and Lymphoma Society website: www.leukemia-lymphoma.org/all_page?item_id=8459.

Leukemia and Lymphoma Society Staff. (2009). Chronic lymphocytic leukemia. Retrieved March 22, 2010, from the Leukemia and Lymphoma Society website: http://www.leukemia-lymphoma.org/all_page.adp?item_id=7059.

Leukemia and Lymphoma Society Staff. (2009). Chronic myelogenous leukemia. Retrieved March 22, 2010, from the Leukemia and Lymphoma website: www.leukemia-lymphoma.org/all_page?item_id=8501.

National Cancer Institute. (2010). Chronic myeloid leukemia: SEER stat fact sheets. Retrieved July 14, 2010, from http://seer.cancer.gov/statfacts/html/cmyl.html.