Your bone marrow produces three types of blood cell: red blood cells, white blood cells, and platelets. Red blood cells carry oxygen through the body. White blood cells help fight infection. Platelets help with clotting.
In people with leukemia, the bone marrow produces abnormal white blood cells. These abnormal cells may work normally at first, but can crowd out normal, healthy blood cells and make it difficult for blood to do its work.
Leukemia can be divided into two groups, depending on how quickly the disease develops and progresses:
- Chronic leukemia gets worse slowly. Abnormal blood cells can still do some of their normal work. Symptoms may take a while to develop, as the number of abnormal cells increases gradually.
- Acute leukemia gets worse quickly. Blood cells are very abnormal and cannot do their normal work. The number of abnormal cells increases rapidly.
Leukemia can develop in lymphoid cells, causing lymphocytic leukemia or in the myeloid cells, causing myelogenous leukemia. Lymphoid cells develop into white blood cells only; myeloid cells develop into all three types of blood cell.
- Chronic lymphocytic leukemia (also known as CLL) accounts for around seven thousand cases of leukemia each year. This disease is rarely seen in children and mostly affects people over the age of 55.
- Chronic myeloid leukemia (also known as CML) accounts for around 4,400 cases of leukemia each year. This disease is mostly seen in adults.
- Acute lymphocytic leukemia (also known as ALL) accounts for just under four thousand cases of leukemia each year. This is the most common type of leukemia in young children but is also seen in adults.
- Acute myeloid leukemia (also known as AML) accounts for more than ten thousand cases of leukemia each year. This disease is seen in both adults and children.
- Hairy cell leukemia and other rare types of chronic leukemia account for just over five thousand cases of leukemia each year.
Patients with leukemia may have a variety of symptoms, including:
- Fevers or night sweats
- Frequent infections
- Feelings of weakness or weariness
- Headache
- Bleeding and bruising easily — including bleeding gums and tiny red spots under the skin.
- Pain in the bones or joints
- Abdominal swelling (as a result of an enlarged spleen)
- Swollen lymph nodes, often in the neck or armpits
- Weight loss