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Leukemia: Overview and Risk Factors

Leukemias are a group of cancers of the blood and bone marrow. They are common, with approximately 30,000 new cases in the United States each year.

There are many types with very different courses: Some tend to be slow–growing and highly curable; others can be fatal without immediate treatment.

Leukemias are classified as acute or chronic. Acute leukemias have a rapid clinical onset and are usually fatal within months without treatment. On the other hand, chronic leukemias often have mild or no symptoms and patients may survive for many years, even without treatment.

Common symptoms include fatigue, anemia, heart palpitations, nosebleeds, easy bruising, excessive menstrual bleeding, fevers, and frequent infections. Weight loss is common. Bone pain may also occur.

Risk Factors

The risk factors for certain types of leukemias are as follows:

  • Acute lymphoblastic leukemia (ALL) usually occurs in children, with a peak age range of three to five years, and is slightly more common in males.
  • Acute myelogenous leukemia (AML) incidence increases with age, with a peak incidence at 60 years, and is more common in males and Caucasian populations.
  • Chronic lymphoblastic leukemia (CLL) is more common in older patients, with a median age of about 60 years, and is more common in males and Eastern European Jews.
  • Chronic myelogenous leukemia (CML) is also more common in older patients, with symptom onset occurring at a median age of about 50 years.
  • Exposure to certain viral infections, including human T–cell lymphoma/leukemia virus (HTLV–1) and Epstein–Barr virus, may increase the risk of some types of leukemias.
  • Tobacco use is a strong risk factor for some types of leukemias.
  • Exposure to benzene and petroleum products, pesticides, and radiation is associated with increased risk. Prior chemotherapy is a risk factor and accounts for up to 10 percent of cases. Some studies suggest that herbicides (including Agent Orange) and insecticides may increase the risk.
  • Children with Down syndrome are at increased risk for acute leukemias.


Leukemia: Diagnosis and Treatment >>