Leukemia Types Aml Myelogenous

Every year, approximately 12,810 new cases of acute myelogenous leukemia (AML) are diagnosed in the United States, according to the American Cancer Society (2010). Acute myelogenous leukemia affects adults more than children, with people over 65 with the highest risk.

Acute myelogenous leukemia occurs when immature blood cells called myeloblasts fail to mature into the different types of blood cells, a process called differentiation. Healthy myeloblasts differentiate into white blood cells, platelets or red blood cells.

If differentiation doesn’t occur, abnormal myeloid cells accumulate in the bloodstream and eventually crowd out healthy blood cells. From the bloodstream, acute myelogenous leukemia can spread into the liver, the spleen or any other organ in the body.

Chronic Myelogenous Leukemia

Like acute myelogenous leukemia, chronic myelogenous leukemia (CML) begins in the myeloid cells. However, these two types of leukemia are different. Chronic myelogenous leukemia requires different treatment and has a different leukemia survival rate.

Acute Myelogenous Leukemia Diagnosis

Like other types of leukemia, diagnosis of acute myelogenous leukemia begins with a history and physical exam. The lymph nodes, spleen or liver may be swollen. Blood tests reveal anemia and low levels of platelets (a blood clotting component). White blood cell count results vary, with normal, high or low levels. Finally, a bone marrow biopsy provides a definitive diagnosis.

Classifying Acute Myelogenous Leukemia

Once AML is diagnosed, the disease is classified into one of eight different subtypes, based on the cells’ appearance. The disease is then classified into FAB (French-American-British) subtypes. Because different sub-groups and types of leukemia respond to different treatments, identifying the disease’s FAB classification is vital.

AML Classification Subtypes

The FAB subtypes of acute myelogenous leukemia are:

  • M0: undifferentiated AML
  • M1: AML with minimal cell maturation
  • M2: AML with abnormal cell maturation
  • M3: Acute promyelocytic leukemia
  • M4: Acute myelomonocytic leukemia
  • M4 eos: M4 with eosinophilia.
  • M5: Acute monocytic leukemia
  • M6: Acute erythroid leukemia
  • M7: Acute megakaryoblastic leukemia.

The World Health Organization (WHO) developed another AML classification system to replace the FAB. This new classification system divides acute myelogenous leukemia into five categories that cover more prognostic factors:

  • AML due to chemotherapy or radiation
  • AML with genetic abnormalities
  • AML with multi-lineage dysplasia (more than one abnormal myeloid cell present)
  • AML not otherwise specified
  • Undifferentiated or biphenotypic acute leukemia (features of both AML and acute lymphocytic leukemia).

The WHO proposal has yet to replace FAB as the most common AML classification system.

Acute Myelogenous Leukemia Survival Rate

Prompt treatment increases a patient’s potential leukemia survival rate. According to Merck Pharmaceuticals (2008), approximately 50 to 85 percent of treated cases result in remission — defined as the reduction or disappearance of cancer symptoms.

Overall, 20 to 40 percent of people who go into remission are free of symptoms five years later. Acute myelogenous leukemia survival rates rise to 40 and 50 percent for younger people who receive stem cell transplants. If a patient hasn’t relapsed after five years of remission, he’s considered cured.

Certain factors affect AML prognosis. Factors that may worsen a patient’s leukemia survival rate include:

  • Advanced age
  • High white blood cell count at the time of diagnosis
  • History of prior leukemia.

Chromosomal alterations can also affect leukemia survival rate, although this role is complicated. While some chromosomal alterations may worsen the prognosis, others may improve the chances of remission or even cure in cases of acute myelogenous leukemia.

Resources

American Cancer Society. (2010). What are the key statistics about acute myeloid leukemia? Retrieved March 22, 2010, from the American Cancer Society website: http://www.cancer.org/docroot/CRI/content/CRI_2_4_1x_What_Are_the_Key_Statistics_About_Acute_Myeloid_Leukemia_AML.asp?sitearea=.

American Cancer Society. (2004). How is acute myeloid leukemia (AML) classified? Retrieved March 22, 2010, from the American Cancer Society website: http://www.cancer.org/docroot/CRI/content/CRI_2_4_3x_How_Is_Acute_Myeloid_Leukemia_AML_Classified.asp?rnav=cri.

Merck Manuals Online Medical Library. (2008). Acute leukemia. Retrieved March 22, 2010, from the Merck Manuals Online Medical Library website: http://www.merck.com/mmpe/sec11/ch142/ch142b.html?qt=leukemia