Consolidation, delayed intensification and high risk block treatment for childhood acute lymphoblastic leukaemia (ALL)

After the induction phase of treatment for acute lymphoblastic leukaemia (ALL) your child has consolidation treatment. Most children then go onto have delayed intensification treatment. Some children might have high risk block treatment, a stem cell or bone marrow transplant or CAR T-cell therapy.

The aim of these phases is to further reduce and get rid of any leukaemia cells that may be left in the bone marrow and cerebrospinal fluid (CSF) Open a glossary item.

How long are these phases of treatment?

The specific treatment, and how long each phase takes depends on the risk of leukaemia coming back. This is mainly based on the measurable residual disease (MRD) test result.

There are 3 consolidation treatment blocks. Most children have 2, but this depends on their risk group. Consolidation treatment 1 last 6 to 7 weeks. Consolidation treatment 2 and 3 lasts 7 weeks.

Delayed intensification phase takes 6, 7 or 12 weeks depending on which risk group your child is in.

The high risk blocks take about 3 weeks each. Your child may have between 3 to 6 blocks.Taking about 10 to 20 weeks in total. 

Your child is likely to have most of these phases of treatment in outpatients or on the daycare unit. If they are having the high risk blocks then your child will stay in hospital for these treatment blocks (inpatient).

Your child might also need to go into hospital if they have an infection. Or they might need help managing side effects for a short time. 

Chemotherapy drugs

The chemotherapy drugs your child is likely to have during consolidation, delayed intensification and the high risk blocks include:

  • cyclophosphamide
  • cytarabine
  • mercaptopurine
  • methotrexate
  • vincristine
  • asparaginase
  • doxorubicin
  • dexamethasone (a steroid)

Other drugs your child might have depending on their risk group include:

  • etoposide
  • idarubicin
  • 6-thioguanine
  • nelaralbine


Steroids are naturally made by our bodies in small amounts. They help to control many functions. But steroids can also be made artificially and used as drugs to treat ALL.

Your child usually has a type of steroids called corticosteroids. These are man-made versions of the hormones produced by the adrenal glands Open a glossary item just above the kidneys.

Corticosteroids include:

  • prednisolone
  • dexamethasone
  • methylprednisolone
  • hydrocortisone

Depending on your child’s treatment plan they will take steroids for up to a week at a time followed by a rest. Steroids also help to get rid of leukaemia cells.

Targeted cancer drugs

Targeted cancer drugs work by targeting the differences in cancer cells that help them to grow and survive. 

Your child might have a type of targeted cancer drug called a monoclonal antibody. Monoclonal antibodies work in different ways. In ALL they work by recognising and finding specific proteins on leukaemia cells. This helps the immune system to find and destroy them.

Some of the monoclonal antibodies your child might have are:

  • blinatumomab (Blincyto)
  • inotuzumab ozogamicin (Besponsa)

If your child has inotuzumab ozogamicin, they have it once a week for 6 weeks.

If your child has blinatumomab they have it as a continuous drip for 4 weeks (28 days), then a 2 week break with no drip. This is called one cycle of treatment. Your child has up to 4 cycles.

They have these through a drip into their bloodstream (intravenously).


Asparaginase is a type of chemotherapy drug.

Asparaginase is an enzyme that breaks down asparagine. All cells need a substance called asparagine to make proteins and create new cells. Unlike normal cells, ALL cells are unable to make their own asparagine. So asparaginase stops the cancer cells from dividing and growing.

Some children will have further doses of asparaginase, but this depends on their risk group. 

Growth factors

Granulocyte colony stimulating factor or G-CSF is a type of growth factor that your child might have during ALL treatment. Growth factors are natural substances that stimulate the bone marrow to make blood cells.

After chemotherapy their white blood cell count drops, so your child is at an increased risk of getting an infection. The longer their white cell count is low the greater their risk. Having a growth factor such as G-CSF helps their white cell count go up more quickly. This could lower the risk of infection.

The different types of G-CSF are called:

  • filgrastim
  • lenograstim
  • pegfilgrastim

Having cancer drugs

Your child has these drugs in a number of ways. They have some:

  • through their central line
  • as tablets or liquid
  • as an injection into a muscle
  • as an injection into the fluid around the spine (intrathecal injection)

Your child usually has a general anaesthetic Open a glossary item, to help them to lie still for their intrathecal injection.

Your child’s consultant and clinical nurse specialist will go through your child’s treatment plan. As well as which medicines are due, how they’ll have them and on which date. 

Ask if you don’t understand. It can help to print off a plan with different colours showing when each medicine is due.

Side effects

The impact of the side effects from of chemotherapy is individual to each child. Your child’s consultant will go through the benefits and potential side effects of treatment with you and with your child if they are old enough.

The doctors and nurses looking after you and your child do everything possible to prevent and treat any side effects that come up. The side effects usually go away quite quickly after treatment stops. But some last longer, or start after treatment has finished.

Common short term side effects of chemotherapy include:

  • increased risk of getting an infection
  • anaemia (low red blood cell counts)
  • increased risk of bleeding
  • hair loss
  • constipation
  • tiredness and weakness
  • feeling or being sick
  • sore mouth
  • allergic reactions

Steroids can also cause side effects. Some of the short term side effects include:

  • changes in blood sugar levels
  • increased appetite
  • high blood pressure
  • mood changes
  • difficulty sleeping
  • swollen hands and feet
  • difficulty walking

Some children have long term side effects from cancer treatment, although this is getting less and less as treatments develop and change.


It’s still important you take your child to see a doctor straightaway if they have any signs of infection when they are at home. Even in the middle of the night. With an infection, your child might:

  • have a temperature of above 37.5°C
  • have pain, redness, discharge, swelling or heat at the site of a wound or intravenous line such as a central line or PICC line
  • be feeling cold or shivery

There are other signs and symptoms of a child having an infection. Your team will tell you exactly what to look out for, who to call and where to go if your child becomes unwell. Some infections can be life threatening for children with leukaemia. Call the 24 hour advice line number if you’re in any doubt.

Life during these phases of treatment

You and your child might feel that you know more about what to expect with this phase of treatment. The types of treatment, hospital procedures and staff might be more familiar to you and your child. This can help you prepare your child before they have treatment.

You might also find this phase difficult to cope with as you, your child and other family members are getting used to life with long term cancer treatment. And you might be feeling tired from travelling to hospital for treatment as well as the other pressures.

It’s okay and important to ask for help if you need it. Your child’s clinical nurse specialist might be a good person to talk to first.

Friends and relatives often wonder how best to support a family who has a child with cancer. You could ask a trusted friend or relative to let people know the things that might help you. This is different for everyone. Ideas for practical support that people might do to help are:

  • making some meals that you can put in the freezer
  • taking the children to and from school
  • helping with the cleaning or laundry
  • doing the shopping
  • driving you and your child to the hospital for blood tests and appointments

This might give you a little bit more energy to focus on looking after yourself and your family.

What next?

Once your child has finished these phases of treatment, they start the final phase of treatment. This is called maintenance treatment. It’s the longest phase of ALL treatment but also the most gentle. Your child won’t have maintenance after having a stem cell or bone marrow transplant or CAR T-cell therapy. 

Last reviewed: 
04 Nov 2021
Next review due: 
04 Nov 2024
  • Cancer in Children – Clinical Management (6th edition)
    MCG Stevens, HN Caron and A Biondi
    Oxford University Press, 2012

  • ALLTOGETHER ALLTogether1 – A Treatment study protocol of the ALLTogether Consortium for children and young adults (1-45 years of age) with newly diagnosed acute lymphoblastic leukaemia. Clinical Study Protocol. Master Protocol.
    Mats Heyman and others
    June 2020

  • Childhood Acute Lymphoblastic Leukaemia
    A Vora
    Springer International Publishing, 2017

  • Oxford Textbook of Cancer in Children (7th Edition)
    H N Caron and others
    Oxford University Press, 2020

  • Electronic Medicine Consortium (EMC)
    Accessed September 2021

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