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What Is Leukemia? The Basics

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Updated August 20, 2014

What Is Leukemia?:

 

Leukemia is a type of cancer that affects the bone marrow and blood. Marrow is the tissue found within the hollow spaces of your bones where "hematopoiesis" or blood cell formation takes place.

There are four main types of leukemia:

  • Acute Myelogenous (or myeloid) Leukemia (AML)
  • Acute Lymphocytic (or lymphoblastic) Leukemia (ALL)
  • Chronic Myelogenous (or myeloid) Leukemia (CML)
  • Chronic Lymphocytic (or lymphoblastic) Leukemia (CLL)

Although these four types of leukemia have a different presentation and different treatments, they all begin in a cell in the bone marrow.

 

Lymphocytic vs. Myelogenous Leukemia:

 

Leukemia is called "lymphocytic" or "lymphoblastic" if the cancerous change begins in a type of marrow cell that forms lymphocytes, which is a type of white cell. Leukemia is called "myelogenous" or "myeloid" if the cancerous change begins in a type of bone marrow cell that, when healthy, goes on to form red blood cells, platelets, and some kinds of white blood cells.

 

Acute Leukemia:

 

Acute leukemias arise from young immature "blast" cells, myeloblasts or lymphoblasts. These acute leukemia cells are non functional and do not work like normal cells. They crowd out the normal cells in the bone marrow, which causes a decrease in the number of new normal cells made in the marrow. Without treatment, acute leukemia will progress rapidly.

 

Chronic Leukemia:

 

Chronic leukemias have little or no immature “blast” cells and usually progress more slowly than acute leukemias. The chronic myelogenous leukemia (CML) cell makes blood cells that function almost normally, but the counts become so high that they crowd out the production of other cells such as red blood cells.

 

 

In chronic lymphocytic leukemia (CLL), too many lymphocytes that do not function are produced. These abnormal cells replace and interfere with the work of normal lymphocytes in the marrow and lymph nodes and weaken the body’s immune system. Over time, both CML and CLL have the potential to transform into aggressive acute leukemias.

 

Risk Factors:

 

As with many types of cancer, the exact cause of leukemia is not known. Many people who have risk factors will never develop the disease, and some leukemia patients have no known risks. For AML, some risk factors have been identified and include:

  • Down Syndrome and other genetic disorders
  • Previous treatment with chemotherapy
  • Chronic exposure to chemicals called "benzenes" in unsafe levels
  • Smoking
  • Exposure to radiation, including radiation to treat other forms of cancer
Studies to determine the cause and risk factors for developing other types of leukemia are ongoing.

 

Signs and Symptoms:

 

The signs and symptoms that a person with acute leukemia displays are the result of the low numbers of red blood cells (or oxygen carrying cells), platelets (which assist in blood clot formation), and white blood cells (which help prevent infection) the diseased marrow is able to produce.

Signs and symptoms of acute leukemia may include:

  • Feeling tired, low energy
  • Difficulty breathing when doing regular activities
  • Pallor or pale skin
  • Fevers or night sweats
  • Cuts and bruises which take a long time to heal
  • Excessive bleeding from minor wounds
  • Tiny red spots under the skin (called "petechaie")
  • Achy bones or joints
  • Frequent infections or illness that you can't seem to "fight off"

 

 

Many chronic leukemia patients will have no signs and symptoms and often discover they have the disease after blood work from a routine check up. Other times, if the disease is more advanced, they may experience similar symptoms to acute leukemia patients.

The signs of leukemia may be vague and can be confused for many other illnesses. If you are concerned about symptoms you are experiencing, it is always a good idea to seek advice from your healthcare provider.

 

Summary:

 

Leukemia is a cancer of the bone marrow, and leads to the production of abnormal blood cells. Eventually, these abnormal "leukemia cells" will take over the normal blood cells such as red blood cells and platelets.

Leukemias are classified by the type of cell they developed from (myelogenous or lymphocytic), as well as by how fast the leukemia grows and progresses (acute vs. chronic). Although these diseases have a common origin, they are all different in their signs and symptoms, how they progress and how they are treated.

Sources:

Caldwell, B.(2007). Acute leukemias. In Ciesla,B. (Ed.)Hematology in Practice (pp. 159-185). Philadelphia, Pennsylvania: F.A. Davis Company.

Finnegan,K.(2007). Chronic myeloproliferative disorders. In Ciesla, B. (Ed.) Hematology in Practice (pp.187-203). Philadelphia, Pennsylvania: F.A. Davis Company.

Munker,R. (2007). Acute Myelogenous Leukemias. In Munker,R., Hillier,E., Glass,J. et al (eds.)Modern Hematology: Biology and Clinical Management- 2nd edition. (pp. 155-173). Totowa, New Jersey: Humana Press Inc.

Munker,R., and Sakhalkar,V. (2007). Acute Lymphoblastic Leukemias. In Munker,R., Hillier,E., Glass,J. et al (eds.)Modern Hematology: Biology and Clinical Management- 2nd edition. (pp. 173- 195). Totowa, New Jersey: Humana Press Inc.

 

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