Your blood is made up of different cell types including red blood cells for carrying oxygen, platelets to help blood clot and white blood cells that fight infections. They all originally come from stem cells, which have the potential to develop into any type of blood cell as they divide and mature. Problems in this process, known as ‘differentiation’, are at the root of all blood cancers. Different types of blood cancer depend on when and how these problems occur.

These problems often lead to your body producing large numbers of immature blood cells that can’t perform their job properly. They can also ‘clog up’ your bone marrow, which prevents other types of blood cells from doing their job too.

Blood Cancer Types

Leukaemia

Leukaemias are cancers that affect your blood cells, mainly your white blood cells and bone marrow. These cells often divide too quickly and don’t develop properly, which compromises your immune system and ability to fight infections.

Many types of leukaemia are either ‘acute’ or ‘chronic’ based on how they behave. In general, acute conditions develop very quickly and need treating aggressively straight away. Chronic conditions usually progress more slowly and intensive treatment may not be needed straight away.

There are four main types of leukaemia:

Acute myeloid leukaemia (AML)

Acute myeloid leukaemia (AML) occurs in your bone marrow, when a type of blood cell called a myeloid cell starts growing abnormally and in an uncontrolled way. Normally your blood stem cells develop into myeloid cells, which then become red blood cells, platelets and certain white blood cells (called neutrophils).

If you have AML, your myeloid cells can’t fully mature and they remain as young, immature cells called myeloblasts. These cells divide too quickly which can ‘clog up’ your bone marrow and stop other blood cells from doing their job properly too.

AML is ‘acute’ because it usually develops quickly, sometimes within a few days or weeks. There are different types of AML – your symptoms will depend on the type you have, the number of leukaemia cells in your body, and where they are.

AML can be classified into ‘high’, ‘standard’ and ‘low’ risk – but this only relates to the type of treatment you will be given, not to the chance of it working.

AML facts

Name: Acute Myeloid Leukaemia (AML)

Cell type: Myeloid cells

Risk: More common in people over 70

Treatment: Chemotherapy and sometimes a stem cell transplant

Other information: AML symptoms develop quickly; treatment often starts straight away

AML and stem cell transplants

If you have AML, it is likely that you’ll need to start treatment quickly after you’re diagnosed. You’ll normally be offered chemotherapy as your main treatment option, although this can vary because certain types of AML are treated differently.

Normally, after chemotherapy, your doctors will consider further treatment to stop the leukaemia coming back. This is where a stem cell or bone marrow transplant comes in. A high dose of chemotherapy, followed by a stem cell transplant, may be the best way to stop the cancer coming back.

Most transplants for AML are allograft transplants – when stem cells are donated to you by someone else. It’s much rarer for AML to be treated with an autologous transplant – when doctors use your own stem cells. This is usually only considered if a stem cell donor cannot be found and your medical team decide it’s a better option than other non-curative treatments.

Acute lymphoblastic leukaemia (ALL)

Acute lymphoblastic leukaemia (ALL) is a blood cancer that stops the white blood cells of your immune system growing properly. It involves blood cells called lymphocytes that develop from stem cells in your bone marrow.

Before these cells are fully formed, they’re called lymphoblasts (immature lymphocytes). Your body needs to make new lymphocytes – but when you have ALL, this process doesn’t work properly. Instead, the lymphoblasts grow too quickly and cannot function properly. These cells can also ‘clog up’ your bone marrow and prevent it from making other blood cells. 

You will probably hear ALL referred to as either ‘B cell’ or ‘T cell’ ALL. This relates to the type of lymphocyte that is affected, and can help your doctor decide on the best course of treatment.

Some types of ALL are characterised by the ‘Philadelphia Chromosome’, which is also found in chronic myeloid leukaemia (CML). The presence of this genetic alteration enables doctors to give Tyrosine Kinase Inhibitors (TKIs), a targeted treatment that should be effective.   

Anybody can get ALL, but it’s the most common type of childhood cancer. It’s an acute condition, meaning symptoms can develop quickly – so it’s very important that treatment is started as soon as possible. 

ALL facts

Name: Acute Lymphoblastic Leukaemia (ALL)

Cell type: Lymphocytes, a type of white blood cell

Risk: Nearly half of all ALL patients are under 10 years old

Treatment: A combination of chemotherapy drugs and possibly a stem cell transplant

Other information: ALL is more common in men than women

ALL and stem cell transplants

In some cases ALL can be treated with chemotherapy alone – however, depending on the type of ALL you have, how it responds to treatment and your general health, you may be offered a stem cell transplant. Your doctor will talk to you about whether a transplant is the best option for you or your child.

If you’re a parent who’s supporting a child through a transplant, we have more advice here.

Most transplants for ALL are allograft transplants – when stem cells are donated to you by someone else. It’s very rare for ALL to be treated with an autologous transplant – when doctors use your own stem cells. This is usually only considered if a stem cell donor cannot be found and your medical team decide it’s a better option than other non-curative treatments.

Chronic myeloid leukaemia (CML)

Chronic myeloid leukaemia (CML) affects a type of white blood cell called a myeloid cell. These cells are a middle step between stem cells and fully-formed white blood cells.

People with CML produce too many granulocytes, a specific type of myeloid cell, that are not fully formed. This is why you may hear CML referred to as ‘chronic granulocytic leukaemia’ (CGL). Over time, these abnormal cells fill the bone marrow, which reduces the number of normal cells in the blood.

CML is not classified into different stages, but it does have three recognised phases: ‘chronic’, ‘accelerated’ and ‘blast crisis’. Very few patients progress beyond the chronic phase today due to the effectiveness of modern treatment.

CML is defined by the presence of a ‘Philadelphia Chromosome’ which forms when parts of your DNA are exchanged between two chromosomes. This causes two different genes (called ‘ABL’ and ‘BCR’) that are normally completely separate, to fuse together and promote uncontrolled cell growth.

CML facts

Name: Chronic Myeloid Leukaemia (CML)

Cell type: Myeloid cells, in particular granulocytes

Risk: More common in people over 65

Treatment: Tyrosine Kinase Inhibitors (TKI) and possibly a stem cell transplant

Other information: TKIs allow most CML patients to live long and healthy lives

CML and stem cell transplants

Most patients with CML are diagnosed during the chronic phase, when treatment with a type of drug called Tyrosine Kinase Inhibitors (TKIs) is possible. Some TKIs are designed to stop cancer cells growing by targeting the Philadelphia Chromosome.

Stem cell transplants are only recommended:

  • if you have CML that hasn’t responded to TKIs, or
  • if you are diagnosed with ‘blast crisis’ CML and treatment gets you back to ‘chronic’ phase CML.

If you do need a transplant, it will be an allograft transplant – when stem cells are donated to you by someone else.