Leukaemia is a cancer of the white blood cells (WBCs) originating in the bone marrow. The cause of most leukaemias is not known, while some are associated with genetic disorders Generally, there is not much that can be done to prevent it. It is often an incidental finding in the laboratory following a routine full blood count which returned abnormal results.
What is it?
Leukaemia is a bone marrow disorder that arises when one abnormal white blood cell begins to continuously replicate itself. There are different types of leukaemia depending on what type of WBC is affected. These cells that are replicating do not function normally, i.e. they do not fight infection as they should and they do not die at the same rate as other WBCs. As they accumulate, the cells fill up the bone marrow and prevent the production of the other normal blood cells in the marrow, leading to anaemia, bleeding, and recurrent infections. Over time, these cells spread through the bloodstream where they continue to divide, sometimes forming tumours and damaging organs such as the kidney and liver. Since the spleen is responsible for filtering the blood and destroying old cells, it may become enlarged and swollen with the abnormal cells, as can the liver and lymph nodes. If the cells reach the central nervous system and build up in the cerebrospinal fluid that surrounds the brain and spinal column, they can cause headaches and seizures.
The bone marrow, located in the soft centre of the body's larger bones, produces immature versions of red blood cells, platelets, and various kinds of white blood cells. The most immature recognisable precursor is called a blast cell. Most of these blood cells mature in the bone marrow before being released into the bloodstream where they are able to carry out their role. The WBCs created are grouped into two main categories: lymphoid and myeloid. Myeloid cells (which include neutrophils, basophils, eosinophils, circulate in the blood, killing and digesting bacteria. Lymphocytescoordinate the immune response and produce antibodies to fight infections. Leukaemia can arise from any one of these white blood cells. It is categorised both by the type of WBC involved and by how quickly it progresses. There are four main categories of leukaemia:
- Acute lymphocytic leukaemia (ALL). Affects approximately 200 adults each year in the UK. This is a rapidly developing disease that is characterized by large numbers of immature lymphocytes. It is the most common type of leukaemia found in children, although it affects both children and adults (usually adults age 65 and older).
- Chronic lymphocytic leukaemia (CLL). This disease progresses more slowly and is characterized by an excess of mature lymphocytes. It tends to be found in those over the age of 55 or 60 and is almost never found in those under 40
- Acute myeloid leukaemia (AML). Affecting people of all ages, although it becomes increasingly common with age and is predominantly found in those over 60, this disease is characterized by production of large numbers of immature myeloid cells that replace other normal cells in the marrow.
- Chronic myeloid leukaemia (CML). Chronic myeloid leukaemia affects approximately 700 people (mostly adults) in the UK each year. These people will have an overproduction of myeloid white blood cells, anda range of immature to more mature cells present.