Risk Factors

Leukemia

• Radiation exposure
• Benzene and toluene
• Cytotoxic agents for chemotherapy (alkylating agents)
• Hereditary syndromes (Bloom syndrome, Fanconi Anemia, Down syndrome)
• HTLV-1 (Human T-cell Leukemia Lymphoma Virus)—common in Japan and Caribbean; rare in US

Acute myelogenous leukemia

Cigarette smoking

Chronic lymphocytic leukemia

Age: more prevalent in middle age and older patients

Polycythemia Vera

None known

Myelofibrosis

None known; triggered by a disturbance of the immune system

Myelodysplastic Syndromes

• Aplastic anemia: 35-60% will develop MDS
• Ionizing radiation: x-rays and gamma rays, atomic radiation; therapeutic radiation
• Exposure to benzene, certain alkylating agents in chemotherapy regimens, and a few other chemicals and drugs
• Certain chromosomal abnormalities
• Down syndrome
• Fanconi anemia
• Neurofibromatosis (Von Recklinghausen disease)

Waldenstrom Macroglobulinemia

None known

Essential Thrombocythemia

None known