Acute Myelogenous Leukemia & Benzene

While the cause of acute myelogenous leukemia is not known in most cases, several factors have been shown to increase the risk of developing this disease. They include:

• exposure to the chemical benzene (see "Who's At Risk of Benzene Exposure")
• exposure to very high doses of irradiation
• exposure to chemotherapy
• Therapeutic radiation (especially drugs known as alkylating agents and topoisomerase inhibitors)
• immunosuppression following organ transplantation
• blood disorders such as:
  • Myeloproliferative diseases such as polycythemia vera or essential thrombocythemia
  • Myelodysplasia (refractory anemia)

Who's At Risk of Benzene Expusure

At-Risk Occupations

• chemical laboratories
• pharmaceuticals manufacturing
• industrial plants that manufacture or use benzene
• oil refineries
• chemical and petrochemical plants (including some offsore installations)
• pesticide (herbicide & insecticide) manufacturing
• printing
• gasoline distribution
• pulp and paper manufacturing
• wood stain and varnish manufacturing
• synthetic rubber production
• adhesive production
• shoe and leather manufacturing

Others at risk include those who work with:

• emissions from burning coal and oil
• motor vehicle exhaust
• spray painting
• industrial solvents
• evaporation from gasoline or service stations (gasoline fumes have 1,000 times the concentration recommended by the National Institute of Occupational and Safety Health)

Acute myelogenous leukemia symptoms result from the body not producing enough healthy blood cells. Healthy bone marrow makes stem cells that grow into the three types of blood cells: red blood cells, white blood cells and platelets. An AML patient's bone marrow makes too many blast cells (immature white blood cells). Normal blast cells turn into a type of white blood cell called granulocytes, but the leukemia blast cells do not. At the same time, the marrow cannot grow enough normal red blood cells, white blood cells and platelets.

Someone with too few red blood cells (anemia) may:

• feel tired
• be short of breath
• look pale

Someone with too few platelets may:

• bleed easily (i.e., cutsthat bleed for a long time)
• bruise more easily than usual
• get pin-head sized spots under the skin
• get cuts that heal slowly or do not heal

Someone with too few normal white blood cells and too many leukemia blast cells may:

• get a lot of infections, for example, a sore throat
• have pain in the bones or joints
• have a mild fever

• bleeding gups
• nosebleeds
• abnormal menstrual periods
• skin rash
• swollen gums (rare)

However, some people with AML do not notice any symptoms. Their AML may be discovered during a blood test.

Most cases have no apparent cause. However studies have found links between the following and some forms of leukemia, including AML:

• some toxins such as benzene
• radiation
• some chemotherapy drugs (including etoposide and drugs known as alkylating agents)
• genetic abnormalities

The earliest observations of patients who had marked elevation of their white blood cells by European physicians in the 19th century led to their coining the term "weisses blut" or "white blood" as a designation for the disorder. Later, the term "leukemia", which is derived from the Greek words "leukos" meaning "white" and "haima" meaning "blood", was used to indicate the disease.

Source: Weill Medical College of Cornell University
	Blood cells infected with acute myelogenous leukemia, also called "leukemic" blood cells.

Leukemia is typically categorized as myelogenous or lymphocytic, with each type having an acute or chronic form. The terms "myelogenous" or "lymphocytic" denote the cell type involved. Acute leukemia is a rapidly progressing disease that affects principally cells that are unformed or primitive (not yet fully developed or differentiated). These immature cells cannot carry out their normal functions. Chronic leukemia progresses slowly and permits the growth of greater numbers of more developed cells. In general, these more mature cells can carry out some of their normal functions. Thus, the four major types of leukemia are acute or chronic myelogenous and acute or chronic lymphocytic leukemia.

The ability to measure specific features of cells has led to further subclassification of the major categories of leukemia. The categories and subsets allow the physician to decide what treatment works best for the cell type and how quickly the disease may develop.

Acute myelogenous leukemia (AML) results from acquired genetic damage to the DNA of developing cells in the bone marrow. The effects are:

1. the uncontrolled, exaggerated growth and accumulation of cells called "leukemic blasts", which fail to function as normal blood cells and
2. the blockade of the production of normal marrow cells, leading to a deficiency of red cells (anemia), platelets (thrombocytopenia), and normal white cells (especially neutrophils, i.e., neutropenia) in the blood.

The better understand the disease and its management, a brief description of normal blood and marrow is provided for background.