Background to Leukaemia
Leukaemia is the most common form of blood cancer in children. Leukaemia is a blood cancer that affects the white blood cells, a really important part of our immune system that fights infection.
When a child has leukaemia, control of blood cell production breaks down. The bone marrow – the soft tissue in the middle of our bones where all our blood cells are made – makes lots of abnormal white blood, or leukaemia cells. These never mature into proper white blood cells, vital to a healthy immune system, and so children with leukaemia are at more risk of infection.
How common is it?
-There are almost 300 children diagnosed with acute lymphoblastic leukaemia each year in the UK.
-There are slightly more boys than girls affected by ALL.
-The most common age at which children are affected by ALL is between two and four years old.
How is it treated?
-The cure rate for childhood ALL in children is now higher than 90%.
Drugs used during treatment:
The following drugs are used in various combinations in the treatment of childhood ALL:
-cyclophosphamide – injected
-cytarabine – injected
-daunorubicin – injected
-dexamethasone (steroid) – tablets or liquid
-vincristine – injected
-intrathecal methotrexate – injected into the fluid around the brain and spine
-oral methotrexate – tablets or liquid
-mercaptopurine – tablets or liquid form
-pegaspargase/crisantaspase – injected.
There will also be a need for antibiotics to prevent bacterial infections and antifungals to prevent fungal infections.
Phases of treatment
The total length of treatment is just over two years for girls and just over three years for boys. Treatment length is different for each because it has been found that, if boys stop treatment at two years, it is more likely that their disease will return (a relapse). You can find a timeline of the treatment phases here.
The treatment described below will be the same whether or not your child is taking part in the trial. This is the standard treatment for ALL in patients aged over one year and under 25 years.
The aim of treatment for ALL is to destroy the leukaemia cells and enable the bone marrow to work normally again. The current standard treatment for ALL consists of drugs called chemotherapy. A combination of chemotherapy drugs is given according to a treatment plan (often called a ‘protocol’ or ‘regimen’). The treatment is given in five phases, or ‘blocks’, which are shown in the diagram, along with further information about each of these phases.
In each phase a combination of several different drugs will be given. The drugs may be given in several different ways:
-by mouth (oral) – as a tablet or solution
-into a blood vessel (intravenous or IV) – this may be as a single injection or by a ‘drip’ (infusion)
-into a muscle (intramuscular or IM) – as an injection
-into the fluid around the spine and brain (intrathecal) – by injection.
Most of the time during treatment your child will be at home and will be able to carry out their normal activities. There will be some times when your child needs to stay in hospital, mainly to reduce the risk of infection. If your child becomes ill, then it may be necessary to have an overnight (or longer) stay for treatment.
Phase 1- Induction (or remission induction)
This is the first five weeks of treatment and it uses intensive treatment to destroy as many leukaemia cells as possible. After four weeks of treatment a very sensitive test called minimal residual disease (MRD) will be used to find out how many leukaemia cells are still present in the bone marrow. The results of this test will decide which type of treatment is to be given in the next phase of treatment (consolidation). The use of the MRD test is now standard for all children being treated for childhood ALL.
Phase 2 – Consolidation
When the induction phase is complete, your child will receive further chemotherapy to destroy remaining leukaemia cells in the blood and bone marrow, and also to prevent leukaemia cells spreading into the brain and spinal cord (the central nervous system or CNS).
The length of this phase and the type of chemotherapy your child receives is based on the results of the MRD test at the end of the induction phase. If the MRD tests show a very low amount of leukaemia left, this is called MRD low risk, but if the test shows a higher level of leukaemia remaining, this is called MRD risk.
Phase 3 – Interim maintenance
This phase lasts for about two months and gives a break of less intense treatment between the consolidation and delayed intensification (phase 4), both of which are intensive. The main treatment during this period will be oral chemotherapy and your child will be at home. There may be a need to admit your child to hospital if treatment is needed for infection or because your child is poorly.
Phase 4 – Delayed intensification
Delayed intensification combines parts of the induction and consolidation phase treatments. This phase will last for seven or eight weeks depending on whether your child is MRD low risk or MRD risk. The aim of this phase is to give intense chemotherapy at a time when the number of leukaemia cells is very low. This will destroy this small number of cells.
Delayed intensification is given on an outpatient basis. (Your child will be at home.) Your child may need to go into hospital if they develop a fever or a very low blood count.
Phase 5 – Maintenance
This is the longest but most gentle phase of treatment. It lasts for just under two years for girls and three years for boys. It is necessary to reduce the risk of the disease coming back (relapse). Maintenance treatment is mainly given on an outpatient basis and your child will only need to go into hospital if treatment is needed for a problem such as an infection.