In addition, leukemia varies among racial and ethnic groups with different genetic make-ups. For example, rates of lymphoma and leukemia (e.g., chronic lymphocytic leukemia, CLL) are especially high in some Jewish populations, whereas Asian populations rarely develop CLL. First-degree relatives (e.g., parents, children, siblings) of CLL patients have a 2- to 4-fold increased risk for this cancer.
Recent studies have shown that, in some types of leukemia (e.g., AML), genetics also may play a role in the risk for recurrence of the disease :
- Cigarette smoking – Cigarette smoking is a known lifestyle related risk factor for leukemia. Potential leukemia causing chemicals in tobacco smoke include benzene, polonium-210, and polycyclic aromatic hydrocarbons (PAHs). These carcinogens (cancer-causing substances) are absorbed by the lungs and are spread via the bloodstream. It is estimated that one in four cases of acute myelogenous leukemia (AML) is the result of cigarette smoking.
- Cancer therapy – Individuals who have received chemotherapy and radiation therapy for previous cancers have a slightly greater chance of getting secondary leukemia (leukemia that arises after therapy). Acute myelogenous leukemia (AML) has been reported after chemotherapy and or radiotherapy for various solid tumors (breast cancer, ovarian cancer), blood malignancies, and nonmalignant conditions. The chemotherapeutic agents most often associated with secondary leukemias are procarbazine, chlorambucil, etoposide, mechlorethamine, teniposide, and cyclophosphamide. The risk is increased when these drugs are combined with radiation therapy. Many secondary leukemias are AMLs that develop within 9 years after treatment of Hodgkin's disease, non-Hodgkin's lymphoma, or childhood CLL. Further chemotherapy often is ineffective in patients with secondary AML; their prognosis is less favorable that that of typical AML patients.
- Other medical therapy and events – Use of the antibiotic chloramphenicol has been linked with the development of childhood leukemia. Other medications, such as growth hormones and phenylbutazone, also have reportedly shown some associations with leukemia. Leukemias and lymphomas have been observed in recipients of organ transplants, and certain immunodeficiency syndromes are associated with leukemias (e.g., infantile X-linked agammaglobulinemia and lymphatic leukemia).
A number of reports have suggested that strong electromagnetic fields (EMF) may be a risk factor for leukemia, although other investigations have failed to confirm these findings. Therefore, National Cancer Institute (NCI) researchers are performing several large-scale studies to try to answer the question of whether or not EMF exposure poses a cancer risk. To date, most publications indicate that leukemia is not related to EMF exposure.
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