Leukemia is a blood cancer that starts in the tissue that forms blood. It affects the white blood cells, important part of the immune system that fight off infections. In leukemia, abnormal white blood cells are produced. These abnormal white blood cells accumulate in the bone marrow and prevent the production of other important blood cells. Most of the problems associated with leukemia are caused by the lack of normal cells in the blood, rather than the leukemia cells themselves.

There are four main types of leukemia, depending on the type of white blood cell and whether it is chronic or acute. Acute leukemia comes on suddenly, progressing quickly and requiring urgent treatment. Chronic leukemia develops more slowly, often over many months or years. They are:

  • chronic myeloid leukemia (CML)
  • acute myeloid leukemia (AML)
  • chronic lymphocytic leukemia (CLL)
  • acute lymphoblastic leukemia (ALL).

Another type of leukemia is the less common hairy cell leukemia.


The symptoms of chronic or acute leukemia are:

  • Swollen lymph nodes that usually don't hurt (more frequently in the neck or armpit lymph nodes)
  • Fever, night sweats
  • Frequent infections
  • Feeling weak or tired
  • Bleeding and bruising easily 
  • Red skin spots
  • Swelling of the spleen or liver
  • Weight loss for no reason
  • Pain in the bones or joints

Leukemia cells travel through the body, so they can affect any organ: the brain, the digestive tract, kidneys, lungs, testes or the heart. Therefore, other organ-related symptoms may occur. The symptoms can differ depending on the number and location where these white cells collect. In chronic types, there may be no symptoms. 


The cause of leukemia is not known. So far, it is considered that environmental and genetic factors play a role. 

Risk Factors

The risk factors for developing leukemia are:

  • blood disorders
  • cancer treatment (chemo- or radiotherapy) 
  • radiation
  • exposure to chemicals
  • smoking
  • family history