What is acute lymphoblastic leukaemia (ALL)?

Acute lymphoblastic leukaemia (also called ALL or ALL leukemia) is a cancer of the blood cells. It is sometimes called acute lymphocytic leukaemia. If you have leukaemia your body makes some abnormal blood cells. These leukaemia cells behave differently from healthy blood cells.

Acute means that it develops quickly and needs to be treated straightaway.

ALL is rare. Around 800 people in the UK are diagnosed with ALL each year. It can develop at any age. But it is more common in children, especially under 4, and in young people. It affects more men than women.

We have separate information about other types of leukaemia.

How acute lymphoblastic leukaemia develops

Blood cells are made in the bone marrow, which is found inside our bones. Every blood cell grows from a stem cell in the bone marrow. There are 2 types of blood stem cell:

  • lymphoid stem cells – these make a type of white blood cell called lymphocytes. ALL affects lymphoid stem cells.
  • myeloid stem cells – these make red blood cells, platelets and other types of white blood cell.

What blood cells do

The stem cell divides to make an early blood cell called a blast. Usually, they stay in the bone marrow until they have fully developed. Once this happens, they go into your blood and do different things:

  • White blood cells help fight and prevent infection
  • Red blood cells carry oxygen to all the cells in your body
  • Platelets help the blood to clot and prevent bleeding and bruising.

What happens in ALL?

ALL affects lymphoid stem cells which make blood cells called lymphocytes. Lymphocytes usually fight and prevent infection. There are 2 main types:

  • B lymphocytes, or B cells
  • T lymphocytes, or T cells.

Normally, these lymphoid stem cells make blasts that develop into healthy B or T cells.

How blood cells divide
Image: How blood cells divide

In ALL some of the blast cells are abnormal and do not develop fully. These are the leukaemia cells. They cannot do the job of a normal blood cell. They also fill up the bone marrow. There is not enough space to make the usual numbers of healthy white blood cells, red blood cells and platelets your body needs.

The levels of these cells in your blood are measured in a test called a full blood count (FBC). We have more detailed information about the blood and bone marrow. This includes what the levels of different blood cells usually are.

Types of acute lymphoblastic leukaemia (ALL)

There are 2 main types of ALL:

  • B-lymphoblastic leukaemia (or B cell leukaemia) – is the most common type where the B cell lymphocytes are affected.
  • T-lymphoblastic leukaemia (or T cell leukaemia) If the T cell lymphocytes are affected.

Your doctors do tests to find out more about the leukaemia cells. This includes information about:

  • other genetic changes inside the leukaemia cells
  • proteins on the surface of the leukaemia cells.

The results of these tests can affect the type of drug treatment you have.

Philadelphia positive ALL

Some people with B cell leukaemia have a subtype called Philadelphia positive ALL (Ph+ ALL). Tests have found a gene change inside leukaemia cells called the Philadelphia chromosome. This change only affects leukaemia cells. It is not inherited and cannot be passed on to your children.

If you have Ph+ ALL, your treatment will include a drug called a tyrosine kinase inhibitor. It targets the abnormal protein the gene change makes.

Symptoms of acute lymphoblastic leukaemia

Most symptoms of acute leukaemia are caused by leukaemia cells filling the bone marrow. There is not enough space to make the usual numbers of healthy blood cells your body needs. This can cause symptoms like:

  • getting infections because you have too few healthy infection fighting white blood cells
  • being pale and tired because you have a low number of red blood cells (anaemia)
  • unusual bleeding, such as bleeding gums or nose bleeds, or bruising due to low levels of platelets, which help the blood to clot.

We have more information about the symptoms of leukaemia.

Causes of acute lymphoblastic leukaemia

Doctors do not know the cause of ALL. But research is going on to find out more about it. Different things called risk factors that may increase the risk of developing ALL.

Some people may have a change in a gene that makes them more likely to develop ALL. More research is needed to understand this.

Genetic conditions

People with certain genetic conditions have a higher risk of developing ALL. These include:

  • Down’s syndrome
  • Fanconi’s anaemia
  • Bloom’s syndrome and
  • ataxia-telangiectasia.

ALL does not run in families (it is not inherited) so other people in your family are not at increased risk of getting it.

High levels of radiation

Being exposed to very high radiation levels, for example after a nuclear accident, increases the risk of developing ALL.

Exposure to high levels of a gas called radon, which can pass from the soil into buildings, is not a risk factor for ALL.

Diagnosis of acute lymphoblastic leukaemia

Some people are diagnosed with ALL after being taken to hospital with symptoms that developed quickly. Others see their GP about symptoms.

If it is possible you have leukaemia, you see a doctor (haematologist) who specialises in treating blood problems. At the hospital the haematologist and specialist nurse will talk to you about the tests you need.

If you think you may be pregnant, let your doctor know. Some tests can be harmful to an unborn baby. It is important to talk to your doctor so they can plan your care safely.

To diagnose ALL your haematologist arranges tests your blood and bone marrow to check for signs of leukaemia cells. Further tests are done to find out more about the leukaemia cells.

Tests for ALL include:

  • Blood tests

    You will have blood tests to check the numbers of the different types of cells in your blood (full blood count) and to look for leukaemia cells.

  • Bone marrow biopsy

    A doctor or nurse takes a small sample of bone marrow usually from the back of the hip bone (pelvis). The sample is sent to a laboratory to be checked for abnormal cells.

  • Immunophenotyping

    This test looks for specific proteins on the surface of leukaemia cells. It helps identify the type of leukaemia and the type of blood cell (B or T cell) that has become abnormal. This test can also be used to look for very small numbers of leukaemia cells during, and at the end of treatment.

  • Cytogenetics and molecular tests

    These tests look for gene changes (mutations) inside the leukaemia cells, including the Philadelphia chromosome (Ph+ ALL). Tests may include:

    • G-banding – the genetic material from a leukaemia cell is coloured using a dye that stains the chromosomes. The chromosomes are then examined using a special microscope.
    • FISH (fluorescence in situ hybridisation) – looks for specific gene changes that may not be seen with G-banding. FISH looks at about 200 cells.
    • PCR (polymerase chain reaction) – this is a very sensitive test that looks for specific gene changes that cannot be seen under a microscope. It looks at a million or more cells. This test can also be used to look for very small amounts of leukaemia during, and at the end of treatment.

After your diagnosis you may have further tests including:

  • Tests to check your general health

    This will include x-rays to check your lungs and heart health, and heart tests such as an ECG (echocardiogram). You may also have blood tests to check how your liver and kidneys are working, or to tests for infections, such as HIV and hepatitis.

  • Lumbar puncture

    A lumbar puncture checks for leukaemia cells in the fluid around the brain and spinal cord. The doctor puts a thin needle into the lower spine and removes a sample of this fluid to send to the laboratory for testing.

  • Tissue (HLA) typing

    If you might need a donor stem cell transplant as part of your treatment you have a blood test to find out your tissue type. The doctors use this to look for a person whose stem cells will be a suitable match for you (a donor).

Treatment for acute lymphoblastic leukaemia

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT). The aim of treatment for ALL is to get rid of the leukaemia cells as quickly as possible so your bone marrow can work normally again.

Treatment usually starts as soon as possible after diagnosis. You may have your treatment as part of a clinical trial. Your doctor will explain the different treatments and their advantages and disadvantages. They will also talk to you about things to think about when making treatment decisions.

Your treatment plan

This depends on:

  • the type of ALL
  • any gene changes (mutations) in the leukaemia cells
  • if the leukaemia cells produce certain proteins.

You usually have treatment in 3 phases:

  • induction treatment - to get rid of the leukaemia cells in your blood and bone marrow (remission)
  • consolidation treatment - to get rid of any remaining leukaemia cells in areas such as the brain or spinal cord
  • maintenance treatment – you take as tablets for 2-3 years to help prevent the leukaemia coming back.

If you have other health problems, you can have less intensive treatment. It has less risk of serious side effects and may be easier to cope with.

To have your induction treatment you usually have a short thin tube called a cannula put into a vein. Before you start consolidation treatment you have a central line or PICC line put in. These are to give you chemotherapy and other treatments.

Your fertility

Your doctor will explain if your treatment may affect whether you can get pregnant or make someone pregnant . Some people may be able to have fertility preservation before treatment. Because treatment needs to start quickly, this is not always possible.

Tests during treatment

During treatment you will have blood tests and samples of your bone marrow taken to check for leukaemia cells. The results tell your doctor how well your treatment is working. It also helps them decide what treatment you may need next to give you the best chance of a cure.

If your test results show very small numbers of leukaemia cells (minimal residual disease) or none, your doctor will say you are in remission.

Treatment options for ALL

The main treatments for ALL include:

  • Chemotherapy

    Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy the leukaemia cells. This is the main treatment for ALL. You have most of the drugs through your line into a vein (intravenously). You take others by mouth as tablets.

    You will also have chemotherapy into the fluid around your spine and brain (called intrathecal chemotherapy). You have it to prevent leukaemia cells spreading to the spine or brain or to treat any leukaemia cells that may be there.

  • Steroids

    Steroids are an important part of your treatment for ALL. They help destroy the leukaemia cells and make chemotherapy more effective. You start taking them a few days before your chemotherapy starts. Steroids can cause side effects. But these will gradually disappear as the dose is reduced.

  • Targeted and Immunotherapy drugs

    Targeted therapy drugs target something in or around the leukaemia cell that is helping it to grow. If you have Ph + ALL you have a targeted drug called a tyrosine kinase inhibitor with chemotherapy. Other drugs called monoclonal antibodies, which are a type of immunotherapy treatment, may be used depending on the type of ALL. If you have B cell ALL you may have a drug called rituximab along with chemotherapy.

    A treatment called CAR-T therapy is occasionally used in young people with B cell ALL.

  • A stem cell transplant

    A stem cell transplant using donor stem cells may be done to reduce the risk of ALL coming back, or if ALL comes back. You have this when you are in remission depending on:

    • the risk of ALL coming back
    • whether a donor is available.
  • Supportive treatments

    Leukaemia and its treatment causes symptoms and side effects. Your doctor and nurses will monitor these. They will give you supportive treatments to prevent or manage them. This may include having:

    • Drugs such as, antibiotics, antiviral and antifungal drugs to treat or prevent different types of infections.
    • A blood transfusion if your red blood cells are low. This will increase your energy levels and reduce breathlessness.
    • A platelet transfusion if your platelets are low. This will reduce your risk of problems with bleeding.
    • Drugs called growth factors may be given to encourage the bone marrow to make white bloods cells.

We have more information about treating ALL.

Managing side effects and recovery

It is important to look after yourself during treatment and while you recover. Some side effects may take months to improve. While your blood cells are still recovering you will need to avoid possible risks of infection.

After treatment, you will also be advised to avoid some vaccines that are not safe to have until your immune system recovers. Your doctor will explain more about this.

How quickly you get back to doing the things you did before, such as socialising, work or college, depends on how your blood cell levels recover.

We have more information about looking after yourself during treatment and recovery.


Leukaemia and its treatments may mean you feel too unwell or tired for sex. If you have low platelets your doctor may advise you to avoid penetrative sex until they recover. Changes, such as hair loss, may also affect how you think and feel about your body (body image). Usually, difficulties slowly improve as you recover.

Even if your treatment may cause infertility it is important to use contraception during treatment and for several months after it.

We have more information about sex during and after treatment in our information about looking after yourself during treatment and recovery.

After acute lymphoblastic leukaemia treatment

Follow up after treatment

After your treatment, you will have regular check-ups which continue for several years. Your doctor asks you how you have been feeling and if you have any new or ongoing side effects. 

You will have regular blood tests to check the number of normal cells in your blood. You may also have bone marrow samples taken to check for signs of leukaemia. Sometimes you may need other tests, such as x-rays or scans.

Many people find that they get very anxious before these appointments. This is normal. It may help to get support from family and friends.

If you have any problems, or notice any new symptoms between appointments, talk to your doctor or specialist nurse as soon as possible. Do not wait for your next appointment.

If ALL comes back

If ALL comes back after treatment you may have further treatment with chemotherapy. The aim is to get a second remission. Some people may be able to have a stem cell transplant from a donor.

Targeted or immunotherapy drugs may also be used. If you have Ph+ ALL, you will be offered a different TKI. Occasionally CAR-T therapy could be a possible treatment option.

Possible long term effects of treatment

ALL treatment can sometimes cause side effects that are permanent or happen months or years later. They may include, infertility, bone thinning, early menopause or an increased risk of heart problems later in life. These will not happen to everyone. Your doctor or nurse can explain how likely they are to affect you. They may give you advice about ways to prevent or manage long-term effects.

We have more information about possible long-term or late effects of ALL treatment.

Well-being and recovery

Even if you already have a healthy lifestyle, you may choose to make some positive lifestyle changes after treatment.

Making small changes such as eating well and keeping active can improve your health and wellbeing and help your body recover.

Related pages

Getting support

Everyone has their own way of dealing with illness and the different emotions they experience. You may find it helpful to talk things over with family and friends or your doctor or nurse. 

Macmillan can offer emotional, practical and financial help and support. If you would like to talk, you can:

The organisations below offer information and support:

  • ACLT (African Caribbean Leukaemia Trust)
    ACLT offers support for people from ethnic minorities affected by leukaemia and related illnesses.
  • Anthony Nolan
    Anthony Nolan is the UK’s largest stem cell and bone marrow register.
  • Blood Cancer UK
    Blood Cancer UK is a blood cancer research charity that provides information and support on any type of blood cancer.

About our information

  • References

    Below is a sample of the sources used in our acute lymphoblastic leukaemia (ALL) information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    NICE (National Institute for Health and Care Excellence). Blood and bone marrow cancers. Available from https://pathways.nice.org.uk/pathways/blood-and-bone-marrow-cancers [accessed August 2021].

    Phelan K and Advani A. Novel therapies in acute lymphoblastic leukemia. Current Hematologic Malignancy Reports. 2018.

    Hoelzer D, et al. Acute lymphoblastic leukaemia: ESMO clinical practice guidelines. Annals of Oncology. 2016. 27 (Supplement 5): v69-v82. 

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Anne Parker, Consultant Haematologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 March 2022
Next review: 01 March 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.