Causes and Risk Factors for Acute Myeloid Leukemia (AML)
Although, the following factors can increase the chance of getting the disease, we could never say for certain that these situations will definitly cause the disease.
Smoking
This is the only proven lifestyle related risk factor. It is a well known fact that smoking is related to cancers of lungs, mouth, throat and larynx (voice box). People, often, do not think that smoking can affect cells that do not come in direct contact with smoke. Particles that cause cancer in the tobacco smoke are absorbed by lungs. They are then spread to different parts of the body through the blood stream. Almost one out of five cases of AML is directly related to smoking.
Chemical Exposure
Long exposure to chemicals such as benzene can be another risk factor. Typically industries related to drugs, rubber and synthetic materials use benzene a lot and people who work in those environments can get AML.
Patients with other cancers who are treated with certain chemotherapy drugs are more likely to develop AML. Some of the drugs linked with these secondary (treatment-related) leukemias include mechlorethamine, procarbazine, chlorambucil, etoposide, teniposide and cyclophosphamide. Combining these drugs with radiation therapy further increases the risk.
Most secondary cases of AML occur within 10 years after treatment of Hodgkin disease, non-Hodgkin lymphoma, or childhood acute lymphocytic leukemia (ALL). Secondary leukemias also sometimes occur following treatment of breast, ovarian, or other cancers.
Radiation Exposure
High-dose radiation exposure (such as being a survivor of an atomic bomb blast or nuclear reactor accident) increases the risk of developing AML. Japanese atomic bomb survivors had a greatly increased risk of developing acute leukemia, usually within 6 to 8 years after exposure.
The possible risks of leukemia from exposure to lower levels of radiation, such as from radiation therapy, x-rays, or CT scans, is not well-defined. Exposure of a fetus to radiation within the first months of development may also carry an increased risk of leukemia, although the extent of the risk is not clear. If there is an increased risk it is likely to be small, but to be safe, most doctors try to limit a person’s exposure to radiation as much as possible.
Certain blood disorders
Patients with certain blood disorders seem to be at increased risk for getting AML. These include chronic myeloproliferative disorders such as polycythemia vera, essential thrombocytopenia, and idiopathic myelofibrosis. Chronic myelogenous leukemia (CML) is another type of myeloproliferative disorder, and some patients with CML can later develop a form of AML. The risk of developing AML is increased further if treatment for these disorders includes some types of chemotherapy or radiation.
Some patients who have a myelodysplastic syndrome (preleukemic condition) may develop AML. These conditions cause defects in blood cell formation, and over a period of years may evolve into leukemia. Patients who develop AML after a preleukemic condition typically have a poor prognosis.
Inherited Syndromes
Acute myeloid leukemia does not appear to be an inherited disease. It does not seem to run in families, so a person’s risk is not usually increased if a family member has the disease. But there are some inherited syndromes with genetic changes that seem to raise the risk of AML. These include:
- Down syndrome
- Fanconi anemia
- Bloom syndrome
- Ataxia-telangiectasia
- Blackfan-Diamond syndrome
Having an identical twin with AML
This risk is largely confined to the first year of life. As mentioned above, most cases of AML are not thought to have a strong genetic link. Many doctors feel the increased risk among identical twins may be due to leukemia cells being passed from one fetus to the other while still in the womb.
Gender
AML is more common in males than in females, although the reasons for this are not clear.
Uncertain, unproven or controversial risk factors: Other factors that have been studied for a possible link to AML include:
- exposure to electromagnetic fields (such as living near power lines)
- workplace exposure to diesel, gasoline, and certain other chemicals and solvents
- exposure to herbicides
So far, none of these factors has been linked conclusively to AML. Research in these areas is ongoing.