CML is a rare cancer. About 700 people in the UK are diagnosed with CML each year. It can occur at any age but is more common in middle-aged and older people.
CML usually develops very slowly, which is why it’s described as a chronic leukaemia.
People with CML make too many granulocytes. These are a type of white blood cell. This is why CML is sometimes called chronic granulocytic leukaemia (CGL). In a person with CML, when the granulocytes are looked at under a microscope, they are immature (not fully developed). The granulocytes fill the bone marrow and stop it making enough normal white blood cells, red blood cells and platelets.
Over time, these abnormal white blood cells collect in the spleen, making it enlarge. The spleen is an organ on the left side of the tummy, underneath the ribs. The spleen:
- produces small numbers of lymphocytes
- stores blood cells
- destroys older, damaged blood cells.
The spleen is part of the lymphatic system. The bone marrow and the lymph nodes (glands) are also part of the lymphatic system.