Acute Lymphoblastic Leukaemia (ALL)
The commonest malignancy (cancer) in children is leukaemia. In medical terms the word acute (versus chronic) means "of recent onset" and does not reflect severity of disease. The vast majority of leukaemias in childhood are acute. They are further subdivided according to the cell type involved (see below). Because the lymphoid cell (lymphocyte) is the most frequent cell of origin for childhood leukaemia, the disease most often encountered is acute lymphoblastic (or lymphatic) leukaemia (ALL).
In the bone marrow, which is the factory producing the cells of the blood, there are three major cell types: white cells (Leukocytes: responsible for fighting infections and foreign tissue), red cells (Erythrocytes: responsible for carrying oxygen) and platelets (Thrombocytopenia: responsible for preventing bruising and bleeding). Leukaemia is defined as a cancer of the white cells. As there are many different kinds of white cells, distinguished either by looking down a microscope or more complicated tests, we can also define the corresponding leukaemia accordingly.The lymphocyte (of which again there are several sub-types) is a white cell which is part of the immune system and has a lot to do with fighting viruses and making antibodies. As described above, leukaemia of lymphoid cells represents about 80% of all childhood leukaemia and is called acute lymphoblastic (lymphphatic) leukaemia (ALL).
One frequent question that troubles many patients and parents is the cause of leukaemia (or other cancers). Although a lot of research has been done on the subject the answer is simply not known. However, research has helped clarify the factors that do not cause leukaemia. This is very important because most people naturally suspect aspects of their diet, life style, heredity, or environment to be responsible. There is no reason to believe that any of those factors are relevant in childhood leukaemia. It is essential that you be reassured that nothing the patient, the family or the wider environment has done has caused the leukaemia. Also, it is not something that parents have passed down in their genes. At the current level of knowledge the process is most easily considered to be an accident occurring in the chromosomes of the cells. Thereby, one particular cell (out of many millions in the body), at one point in time, accidently alters the chromosomes in some way so as to lead to an escape from the usual control mechanisms that regulate growth and proliferation of cells in the body.
Although one can suspect leukaemia to be present from looking at blood tests, the diagnosis is always established by checking the bone marrow. This is done by inserting a needle into the hip bone (at the back), sucking out a small amount of marrow (which looks like thick blood) and examining it under a microscope as well as doing other tests. Apart from making the diagnosis of ALL by checking the marrow, we also look for possible spread to other places. For this reason spinal fluid is also obtained by inserting a needle between the spines in the lower back, and x-rays including a chest x-ray are usually performed. With all this information, as well the findings from examining the patient and taking a history, it is possible to discuss a plan of management suitable for that individual child or adolescent and predict the likelihood of response, complications and long term cure rate.
All the paediatric Oncologists (doctors specialising in treating children with cancer) in Australia have agreed to participate in a protocol that has standardised the optimum care of childhood ALL patients around the country. There are two major objectives: firstly, to offer treatment that is as good as any available in the world; and secondly, to make further advances in both the cure rate and minimising side effects. The second objective can only be achieved by addressing specific questions in a large number of patients throughout Australia. For that reason, in the later phases of the treatment programme two possible options are being considered. Both options are reasonable ways to treat leukaemia and provide good results. However, if one is slightly better than the other, that cannot be discovered unless patients are randomly assigned to one or other of the options and followed for a long time thereafter. If we knew (or were to discover) that one treatment is better than the other, then there would be no question to ask and it would be quite wrong to continue the study. However, as long as on current evidence both treatments are thought to be equally effective, it is both safe and important to find out if one holds advantage over the other, even if that advantage turns out to be a very small one. This is the way to make further progress in a disease which already has very successful treatment available.
The details of the treatment programme and expectations for each patient will depend on what are known as "prognostic factors" at diagnosis. In other words, various factors such as age, the number of leukaemic cells found in the blood, the precise type of leukaemic cells on microscopic analysis and some more complex tests will influence subsequent management. These aspects and a precise plan need to be discussed for each individual patient at the time of the inital and subsequent conferences. At the same time, details of the options available as described in the paragraph above are explained in detail and permission is sought for each patient to participate in the national study. Families and patients will be given a typed summary of the treatment programme which acts as a "road map" of the months to follow. The protocol is divided into various phases and each will be explained step by step.
The first phase of every patient's protocol is to bring the leukaemia under control (remission). Remission is achieved when on available tests leukaemic cells can no longer be found anywhere in the body. This does not mean a cure, because if treatment should then be stopped, all patients would get their leukaemia back in a short time. However, it is the first step to allow the possibility of cure to follow. The subsequent phases of the protocol are aimed to consolidate and intensify the remission and then to maintain it for approximately two years at which time treatment is usually stopped.
The mainstay of treatment is chemotherapy, meaning drugs designed to fight leukaemic cells. Drugs can be given as tablets, injections under the skin or injections directly into veins. All these methods ensure that the drugs get into the blood stream so they can go wherever blood goes and therefore wherever leukaemic cells may be hiding.
However, the brain and the spinal cord (central nervous system) are protected from drugs given intravenously (under usual circumstances for good reason) and may therefore harbour leukaemic cells as if in a "sanctuary" site. To overcome this, injections of chemotherapy are also put into the spinal fluid and sometimes radiation therapy is also given to the patient's brain. These details will be discussed and explained for each individual patient and family.
The vast majority of treatment for ALL is given on an outpatient (Clinic) basis. Occasional admissions to hospital are necessary for drugs that are given by a vein over several hours, or for complications that may arise. The most frequent complication requiring hospitalization is an infection which needs to be treated with antibiotics given intro a vein. The risk of various infections, other complications of treatment and ways we have of minimising these side-effects are addressed in other sections of our resource library. It is important to be clear on these and ask questions as often as necessary, in addition to written information that will be available. The initial admission to hospital at the time of diagnosis may be only a few days, providing infection is not already present and no other complications occur. Arrangements will then be made for the treatment to follow and appointments for the clinic at Sydney Children's Hospital in conjunction with visits to a doctor or centre of your choice which is nearer to home. Our aim is to provide the best available care whilst minimising your need to travel by involving the local doctors and hospitals as much as possible.
By way of general information (which varies for individuals) about 97% of patients who present with ALL successfully achieve remission (not cure) with the drugs used. If leukaemia returns some time after that, we call that relapse. The way a relapse is handled depends on where and when it is. However, in all cases other treatment options are still available. On current figures, about 2/3rds of patients are expected to remain in remission and eventually be cured of their disease. After treatment is finished, we continue regular checks at increasing intervals as time goes by. In years to come we look for and try to correct late side-effects on growth, education, development, reproductive function and other potential problems.