Chronic myeloid leukemia (CML) is a type of cancer that causes the body to produce large numbers of young white blood cells (myeloblasts). These myeloblasts, called leukemia cells, cannot fight infection very well.

When leukemia cells build up in the blood and bone marrow, there is less room for healthy blood cells. This can cause infections, anemia, and easy bleeding.

Most people with CML have a gene change (mutation) called the Philadelphia chromosome.

CML usually gets worse slowly. It is sometimes referred to as chronic myelogenous leukemia.