About Leukaemia

There are 137 different types of blood cancer and four main types of leukaemia.

What is leukaemia?

Leukaemia is a type of blood cancer. It starts in the blood-forming tissue, usually the bone marrow, and leads to the over-production of abnormal white blood cells, the part of the immune system that defends the body against infection. 

To understand leukaemia, it helps to know more about your blood, which has three main cells groups. They have different jobs: 

  • White blood cells fight off infection
  • Red blood cells carry oxygen around your body, and take carbon dioxide back to your lungs so you can breathe it out
  • Platelets helps your blood clot up, to prevent bleeding

Your body is making fresh new blood cells all the time, to replace old ones that have worn out and died off. This happens mainly in your bone marrow. When you're healthy, this system is finely balanced in a process called haematopoiesis. 

How blood cells are made - wide-01.jpg
  • The process starts with a stem cell, which is an immature cell that can develop into all types of blood cells.
  • When the stem cell divides, it can either produce more stem cells, or other immature blast cells that develop into mature blood cells over time. 
  • In this process of specialisation, immature blast cells become either lymphoid or myeloid cells. 
  • Lymphoid cells are a type of white blood cells. They help fight infection, and they include B lymphocytes and T lymphocytes.
  • Myeloid cells go on to form red blood cells, platelets and other types of white blood cells such as monocytes and granulocytes. 

Leukaemia develops when this process goes wrong, and the white blood cells develop in an uncontrolled way. Your body is making too many white blood cells and they may not be fully formed or mature.  This means your white blood cells can't do their job of fighting infection. They may also crowd out your red blood cells and platelets, so they can't work properly either. 

There are four different types of leukaemia

The leukaemia name partly depends on whether it is chronic or acute:

  • Chronic leukaemia may take a while to get worse
  • Acute leukaemia gets worse quickly without treatment. The white blood cells are also more abnormal than in chronic leukaemia. 

The leukaemia name also tells you what specific type of white blood cell is affected, myeloid or lymphoblastic.

Leukaemia diagnosis, tests, and treatment

Who can be affected by leukaemia?

People of any age, gender and ethnicity can develop leukaemia. Whilst the highest incidence of leukaemia is observed in older adults, leukaemia is the most common of all the cancers diagnosed in children. Leukaemia is more prevalent in white and black males than in Asian males and more common in white females compared to Asian or black females. 

Leukaemia tends to occur in elderly people and children. In the UK, the average age at diagnosis of leukaemia is 71 years, but leukaemia is also the most common childhood cancer; it accounts for about 33% of all cases of cancer in those under 14 years of age.