Learn Topic
12 Articles

Blood cancers and blood disorders

An introduction to blood cancers and blood disorders

Graphic of blood and cancer cells

Blood cancers and blood disorders are caused by changes in the genes of blood cells (1).

Mostly cancer gene changes happen during your lifetime. So you have not inherited them and you can not pass them on to your children. But in some blood disorders, such as sickle cell disease or thalassaemia, you are born with faulty genes that you’ve inherited from your parents.


Our bodies make billions of new blood cells every day. Gene faults (mutations) can come about during this process. When stem cells divide and multiply, the DNA is copied from one cell into two new cells. Sometimes spelling mistakes happen in the DNA code when it is copied. Mostly the mistake will cause the cells to die, but occasionally they survive and then reproduce the DNA mistake in new cells when they multiply.

Cancers develop because cells gather a number of gene changes over time which affect how they behave. Sometimes a cancer gene is inherited, for example, breast cancer genes, BRCA2 and BRCA2. But mostly, these gene faults develop during a person’s lifetime.

Genes affect how a cell behaves. Unlike normal blood cells, cancer cells:

  • are not fully developed: they are ‘immature’
  • have lost the failsafe mechanism that makes cells die when they’re damaged: they are ‘immortal’
  • grow and multiply when they should not: they have uncontrolled growth.

As cancer cells do not die when they should and multiply uncontrollably faulty blood. cells flood the bone marrow and bloodstream and crowd out other healthy blood cells (1).

Types of blood cancer

There are three main types of blood cancers - leukaemias, lymphomas and myeloma.

Find out more: Leukaemias, Lymphomas, Myeloma.

Blood disorders

Some blood disorders are caused by a specific gene fault inherited from your parents. If you’re born with a disease like sickle cell disease or thalassaemia, you need to inherit the gene fault from both parents to have the disease (3). There is now screening for these gene faults in some communities where they are more common (4).

Some conditions are in between a cancer and a blood disorder. There have been a few cancerous gene changes in cells, but not enough to cause full-blown cancer. Myelodysplastic syndromes are examples (2).

Dysplastic means abnormal and myelo means bone marrow. So in these conditions, bone marrow cells are abnormal; they have some properties of a cancer, but not all of them. This explains why some people with MDS are at risk of developing leukaemia: the MDS cells already have some of the necessary gene faults (2).

Find out more: Types of blood disorders


1. How leukemia forms. Leukemia symptoms and causes. Mayo Clinic. Accessed July 2021.

2. Kennedy, JA and Ebert, BL. The genetic trajectory of MDS: from clonal hematopoiesis to secondary AML. Clinical implications of genetic mutations in Myelodysplastic Syndrome. Journal of Clinical Oncology, 35(9), pp968-74. Published online February 2017.

3. Oxford handbook of critical care nursing (2nd ed). Haematology: sickle cell anaemia. Oxford Medicine Online. Published online March 2016.

4. Haematology: haemoglobinopathy. Oxford handbook of general practice (5th ed). Oxford Medicine Online. Published online June 2020.

5. Haematology: full blood count and ESR. Oxford handbook of general practice, 5th ed. Oxford Medicine Online. Published online June 2020.

6. Bone marrow tests. NIH National Heart, Lung and Blood Institute. Accessed July 2021.

stem cells
What are blood stem cells?
Blood stem cells in the human body
Read more
Blood cancers and blood disorders
Get involved, support our mission
Join the register, raise awareness, do a fundraising challenge - you choose!