Leukemia is a cancer that begins in the bone marrow and spreads to other parts of the body. It causes the bone marrow to produce too many white blood cells. More than 40,000 new cases of leukemia are diagnosed each year with adults affected 10 times more often than children. However, leukemia accounts for 31 percent of all childhood cancers.

Symptoms
Leukemia symptoms can occur suddenly or gradually. Symptoms of leukemia may include:

• fatigue
• paleness
• bone and joint pain
• weakness
• weight loss
• repeated infections
• fever
• tendency to bruise easily
• nosebleeds or other hemorrhages.

In children, these signs often appear suddenly. In adults with chronic leukemia, on the other hand, the disease can progress slowly with few noticeable symptoms. In these cases, the diagnosis often follows routine blood tests. 

Causes and Risk Factors
Researchers have identified a variety of causes and risk factors for leukemia, including:

• Family history (one of the strongest risk factors)
• Cigarette smoking
• Medical radiation, such as that used in cancer treatment
• Children with Down syndrome and certain other genetic abnormalities
• Obesity
• Exposure to certain chemicals such as benzene, a component in gasoline
• People infected with the human T-cell leukemia virus, which may be spread by shared syringes, blood transfusions, sexual contact and from mother to child at birth or through breastfeeding
• People with the blood disorder myelodysplasctic syndrome.

Diagnosis
Leukemia can be difficult to diagnose early because some early symptoms often resemble those of other, less serious disease like the common flu. Your physician will order blood tests and a subsequent spinal tap and/or bone marrow biopsy if leukemia is suspected.

Treatment
Treatment for leukemia varies greatly and depends on the type and stage of your disease. Common treatments include: 

• Chemotherapy
• Radiation
• Biologic therapy
• Hematopoietic cells or bone marrow transplant - replaces bone marrow that has been destroyed by treatment with high doses of anti-cancer drugs or radiation.

Prevention
Unfortunately, there are no proven methods to prevent leukemia. Some of the risk factors for leukemia, such as aging or Down syndrome, are unavoidable.

Smoking is the biggest risk factor you can avoid. One in every four cases of leukemia is linked to smoking. If you smoke cigarettes, now is the time to quit. Smoking also puts you at risk for other kinds of cancer.

Another risk factor you can be avoid is prolonged exposure to benzene and other known cancer-causing chemicals. If your job requires you to handle large quantities of gasoline, paint, industrial solvents, plastics, pesticides or detergents, take precautions (like wearing the proper safety equipment) to limit your exposure.