Chronic myelogenous leukemia (CML) is a cancer of the blood cells. It affects your blood cells and bone marrow -- the soft part inside your bones where blood cells are made.
Chronic myelogenous leukemia can also be called chronic myeloid leukemia and chronic granulocytic leukemia. It typically affects older adults and rarely occurs in children, though it can occur at any age.
Most people will never know what caused them to get CML. You don't typically get it from your parents or from infections. Your smoking habits and diet don't seem to raise your chance of getting it either.
The only known risk is if you've been in contact with high levels of radiation.