Leukaemias have their origin in the blood stem cells found in the bone marrow, which is the red spongy part inside the bones. In a healthy child the blood stem cells can be of two sorts, lymphoid and myeloid, and when they mature they give rise to the different kinds of blood cell, which are:

1) Red blood cells: these are the cells that transport oxygen from the lungs to the cells in the rest of the body.

2) Leukocytes, or white blood cells: these are the cells that help combat infections. There are various kinds of leukocyte such as neutrophils, monocytes and lymphocytes.

3) Platelets: these are the cells that help the blood to coagulate to control bleeding.

Acute lymphoblastic leukaemia (ALL) is a cancer formed by immature lymphocytes, known as lymphoblasts. These cells prevent the growth all the other blood cells. ALL is the most frequent childhood cancer.

Lymphocytes are a kind of leukocyte, or white blood cell, and they can be of two sorts, B and T. Depending on whether the lymphoblasts have their origin in B or T cells the ALL is called ALL- B or ALL- T.

The exact causes of ALL are not known. Research in this field is it important and more knowledge is being in gained about the genetic changes that occur in leukaemia cells. Nevertheless, the factors contributing to, and the causes of, most childhood ALL are unknown.

A minority of children do have some genetic disorders that predispose them to developing ALL. This is the case with children with Down syndrome or other syndromes such as Li-Fraumeni syndrome, ataxia–telangiectasia syndrome, and others. Other factors that increase the possibility of developing leukaemia include exposure to radiation prior to birth (X-rays), and having been administered chemotherapy for another cancer.

The siblings of a child with leukaemia have a slightly increased risk of developing the disease in comparison to other children. But this risk is very low, less than one in 1,000.

Leukaemia, like other kinds of cancer, it not contagious.

The kind of chemotherapy the patient will receive depends on the type of leukaemia and the patient's probabilities of relapse. There are three kinds of treatment that are more, or less, intensive, depending on the risk of relapse. Patients are classified into the following groups based on this risk:

1) Standard risk, 2) Intermediate risk, 3) High risk

The intensity and length of chemotherapy varies in accordance with the risk group. However, regardless of the group to which they correspond, all children being treated, will receive

1) An initial treatment, called induction therapy, of intensive chemotherapy, followed by

2) consolidation therapy or the intensification treatment, followed by

3) maintenance therapy which consists of low intensity chemotherapy in the form of tablets, meaning that in most cases the child can lead an almost normal life and go back to school, do sport and participate in other extracurricular activities. For a small group of children with a greater risk of relapse, instead of maintenance treatment, a bone marrow transplant is performed.

15-20% of children may suffer relapse. Most relapses take place during the first five years from the time of diagnosis, especially during the first two years after treatment has concluded. In cases where there has been a relapse, chemotherapy is administered again and, depending on the case, a bone marrow transplant is performed.

If a child with ALL has a relapse, the chances of a cure, and the treatment, will depend on a number of factors, mainly:

1) the length of time between diagnosis and the relapse, the longer the better

2) whether it is a B- or T-type ALL

3) the location of the relapse (bone marrow or others such as the nervous system, testicles, etc.)

4) the response to treatment for the relapse

Treatment will generally consist of chemotherapy that is more intensive than the chemotherapy received initially and often, a bone marrow transplant. Some children who have had a relapse may be cured without receiving a transplant.

In recent years, as well as chemotherapy, there have been new treatments that may substitute or supplement chemotherapy, such as immunotherapy and treatments directed at molecular targets. (See New Treatments).

When the treatment is over, the child will have regular check-ups with their hematologist and, if necessary, other specialists. These check-ups are carried out in order to detect any possible relapse, monitor progress, and treat any possible long-term complications. Over time the check-ups are further and further apart, until they occur just once a year. In the long term it is recommended to have a check-up at least once a year in order, at an early stage, to detect and if necessary treat, any consequences arising from the treatment or the leukaemia.

We will now turn to some general recommendations in response to some of the most frequent questions raised by parents with children with leukaemia.

Will their hair fall out? When? Should we have it cut?

After the chemotherapy they receive to treat the leukaemia their hair will fall out. This usually happens two or three weeks after the start of the course of chemotherapy. If the child has long hair, it is best to cut it short before it starts to fall out. It is neither necessary nor appropriate from the psychological point of view, to have their hair cut during the first days in hospital. Neither is it necessary to explain that this will happen right at the beginning, but the child should be told about it before their hair starts to fall out. Their hair will start to grow again two or four weeks after having started the maintenance treatment phase during which the chemotherapy is of lesser intensity.

Hygiene

Given that the child will have reduced defences against infection because of the disease itself and also because of the treatment administered, good standards of bodily hygiene must be maintained as well as cleanliness in the hospital room, at home and with any toys.

Toys which accumulate a lot of dust are discouraged, as are cardboard boxes. Food should not be left outside the fridge. Plants in the room are prohibited because the soil contains fungal spores.

Keeping things neat and tidy helps the hospital's cleaning staff with their work.

Visits

It is advisable to keep the number of visitors in the room to a minimum because they might be carrying infections. It is recommended that there be no more than two accompanying visitors and that they wash their hands before entering the room. If any of the visitors is suffering from an infectious process (a cold, or conjunctivitis, etc.) it is best for them not to come.

Should this person be the mother, the father, or someone else who looks after the child and their presence is required, they should wear a mask and wash their hands before coming into contact with the child.

Diet

Children receiving intensive chemotherapy treatment must have a varied diet. When there is a low leukocyte count it is best to avoid raw foods that can not be peeled, such as lettuces, strawberries and tomatoes, etc.

Sometimes chemotherapy takes your appetite away or even causes nausea. On days when chemotherapy is being administered you should not try to force the child to eat because it can be counter-productive.

In contrast, the corticoids (prednisone and dexamethasone), which are administered in some phases of the treatment, can greatly increase the appetite and even cause related anxiousness. While it is perfectly acceptable to let them eat a little more than that which is served in the hospital, they should not be allowed to eat without measure, something that often does not agree with them, and which can cause stomach aches.