AML, one of the most common leukemias in adults, is diagnosed in about 13,400 people in the United States each year. The incidence of AML rises in those over 50 and the average age at diagnosis is 67. The disease affects more men than women.
How AML Develops
The bone marrow contains immature cells called hematopoietic stem cells, which can mature into a range of different kinds of blood cells, including white blood cells. Normal, healthy white blood cells, which fight infection, have a very short life span — sometimes only a few hours long — and are continuously replenished in the bone marrow. They proceed through their life cycles in an orderly way, and when they die they are replaced by new cells.
AML arises in cells that should go on to become specialized white blood cells called granulocytes and monocytes. When their DNA or genetic material becomes damaged or mutated, these poorly functioning cells begin reproducing and cannot mature beyond an early stage in their life cycle. Over time these immature cells — called blasts — take over the bone marrow and displace the normal red and white blood cells and platelets that are produced there. As the numbers of normal cells decline, patients may develop anemia, a condition characterized by a lack of oxygen-carrying red blood cells; infections caused by low counts of disease-fighting white blood cells; and bruising and bleeding, resulting from low levels of platelets, which are the blood component that plays a crucial role in blood clotting and wound healing. Leukemic cells may also invade the liver, spleen, lymph nodes, skin, and other organs.
Risk factors for developing AML can include smoking, inherited, or genetic, traits, and exposure to cancer-causing agents in the environment. There is only a very small chance that a person who has one of the few known risk factors for AML will develop the disease.
Cigarettes contain dozens of cancer-causing chemicals and are most often linked to solid tumors such as lung, bladder, and head and neck cancers, but smoking is also believed to be a risk factor for leukemia. Researchers estimate that about 20 percent of AML cases are related to smoking.
People who are exposed to high doses of radiation (from the explosion of an atomic bomb, from working in an atomic weapons plant, or from a nuclear reactor accident) have a heightened risk of developing leukemia. People who have been exposed over long periods to high levels of solvents such as benzene — in the workplace, for example — are also at risk.
People who were treated in the past with chemotherapy or radiation treatments for cancer have an increased risk of developing leukemia, because chemotherapeutic agents and radiation target rapidly dividing cells such as those of the bone marrow. These agents can cause mutations, or changes in a cell’s DNA, that later can lead to malignancies including leukemia. AML is linked to treatments for Hodgkin’s disease, non-Hodgkin’s lymphoma, childhood acute lymphocytic leukemia, and other malignancies such as breast and ovarian cancer.
People who have a myelodysplastic syndrome, a preleukemia condition, or who have rare genetic syndromes such as Down syndrome, Fanconi anemia, ataxia-telangiectasia, and Bloom syndrome are at slightly higher risk for developing leukemia.
Many people with one or more of these risk factors never develop leukemia. Most of the people who do develop AML have no risk factors at all. Scientists do know that most cases of leukemia are associated with specific gene mutations, but, in most cases, it is not clear what causes those mutations.
The symptoms of acute leukemia generally appear suddenly and can be similar to those of a virus or flu. They can be severe enough that they prompt patients to see a physician shortly after their onset and may include:
- fever, headache
- loss of weight and/or appetite
- easy bruising and/or bleeding
- weakness and fatigue
- coughing, shortness of breath
- frequent minor infections or poor healing of minor cuts
- swollen lymph nodes, stomach, head, arms, and gums
- tiny red spots on the skin
- bone or joint pain
- difficulty maintaining balance
- blurred vision
- seizures, vomiting
- an enlarged testicle with no pain
These symptoms can also be associated with a wide range of conditions and illnesses other than leukemia. But if these problems persist, consult a physician.