Leukaemia is a cancer of the bone marrow. It affects the cells in the bone marrow that produce white blood cells.The four main types of leukaemia are:

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

Each type has its own characteristics and treatment.

What is Acute Lymphoblastic Leukaemia (ALL)?

Acute lymphoblastic leukaemia (ALL) is a rare type of cancer, affecting approximately 200 adults per year in the UK.

ALL is a cancer of the white blood cells. Normally, white blood cells grow and divide in an orderly and controlled way. In leukaemia this process gets out of control as the normal signals that stop the body making too many cells are ignored. So the cells go on dividing and do not mature.

In ALL there is an overproduction of immature lymphocytes, called lymphoblasts (sometimes referred to as blast cells).

These immature cells fill up the bone marrow and stop it from making blood cells properly. As the lymphoblasts do not mature, they can't do the work of normal white blood cells (fight infection). Also, because the bone marrow is overcrowded with immature white cells, it can't make enough healthy red cells and platelets.

ALL occurs most frequently in children under 15; in adults it is more common between the ages of 15–25 and in older people. It's slightly more common in males than in females.