What is acute lymphoblastic leukaemia?

Leukaemia is a cancer of the white blood cells. People with leukaemia usually have more white blood cells than normal. These leukaemia cells behave differently from healthy white blood cells.

The four main types of leukaemia are:

Each type of leukaemia has its own characteristics and treatment.

Acute lymphoblastic leukaemia (ALL)

Acute lymphoblastic leukaemia is a rare type of cancer. It affects about 650 adults a year in the UK. ALL is most common in children and young people up to the age of 25, and in older adults over 75. It affects slightly more males than females.

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

People with ALL make too many immature blood cells, called lymphoblasts (sometimes referred to as blasts). As the lymphoblasts do not mature, they can’t fight infection as normal white blood cells do. These immature cells fill up the bone marrow, which means there is not enough space to make all the healthy white cells, red cells and platelets your body needs.

ALL and lymphoma

ALL is very similar to lymphoblastic lymphoma, which is a cancer of the lymphatic system. In ALL, the abnormal lymphoblasts are generally in the blood and bone marrow, although occasionally they can build up in the lymph nodes. But in lymphoblastic lymphoma they are mainly in the lymph nodes or thymus gland. The two conditions are often treated in very similar ways.

Types of acute lymphoblastic leukaemia

Knowing what type of ALL you have helps your doctors to plan your treatment.

Doctors usually use the World Health Organisation (WHO) system to group ALL into different types. This is based on the type of blood cell that has become cancerous.

There are three different types of ALL. The most common type is early B-lymphoblastic leukaemia. About 30% of people (nearly 1 in 3) with this type of ALL have the Philadelphia chromosome in the leukaemia cells.

Other less common types of ALL are:

  • mature B-lymphoblastic leukaemia
  • T-lymphoblastic leukaemia.

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