The blood comprises red blood cells, which transport oxygen; white blood cells, which fight infection; and platelets, which prevent bleeding.
The stem cells in the bone marrow differentiate into myeloid cells, which fight bacterial and parasitic infections and prevent tissue damage from spreading; and lymphocytes, which fight viral infections.
Leukaemia is cancer of the white blood cells. It can be acute or chronic. The former progresses rapidly, and the latter, gradually.
Both types are classified according to the type of white cell involved, i.e. acute myeloid and lymphoblastic leukaemia; and chronic myeloid and lymphocytic leukaemia.
Acute lymphoblastic leukaemia (ALL) affects the lymphocyte white blood cells, with large numbers of immature (blast) cells released into the bloodstream from the bone marrow, leading to a decrease in red blood cells and platelets.
The lymphoblast cells are less effective than the mature cells in combating infections.
ALL is uncommon but affects both adults and children. It is the most common type of leukaemia in children. Its progress is rapid and aggressive, thereby requiring immediate treatment.
ALL is due to a mutation in the stem cells that causes blast cells to be released into the blood stream. Whilst the actual causes are unclear, the known risk factors include previous chemotherapy with certain medicines; smoking; overweight and obesity; some genetic disorders e.g. Down’s syndrome; and weakened immunity e.g. HIV/AIDS and immunosupressants.
ALL usually starts slowly before becoming severe rapidly as lymphoblast cells in the bloodstream increases rapidly.
The features include tiredness, pallor, breathlessness, high fever, unexplained weight loss, bleeding from various sites like gums, nose and skin, bone and joint pain, frequent infections in a short period of time, swollen lymph nodes and enlarged liver and/or spleen causing abdominal pain.
Sometimes, the lymphoblast cells spread into the central nervous system, causing headache, fits, vomiting and blurred vision.
The complications of ALL include weakened immunity, bleeding and infertility.
Weakened immunity is due to the lack of mature white blood cells or the side effects of medicines used in treatment. This leads to an increased risk of infection and increased intensity in any infection that develops.
Easy bruising and bleeding from various body sites are common because of the low platelets. The bleeding may be excessive and may occur in the skull, lungs and gastrointestinal tract.
The features are that of the bleeding site, such as headache, coughing out blood and passing out blood in the faeces.
Bleeding should be regarded as a medical emergency.
Temporary or permanent infertility is often a consequence of many of the treatments. The latter is more likely in those who have received high doses of chemotherapy and radiotherapy prior to stem cell transplant.
The initial diagnosis of ALL is made from blood tests. An increase in lymphoblast cells or a low blood count would lead to a referral to a physician or a specialist in blood conditions (haematologist).
A bone marrow biopsy confirms the diagnosis. This is carried out under a local anaesthetic in the skin on the back of the hip bone with a thin needle inserted to remove a sample of bone marrow, which is then examined for cancer cells.
If present, the type of leukaemia will be determined. There may be some bruising and tenderness after the biopsy.
Additional tests are done to detect the extent of ALL to guide decision-making.
Computerised tomography (CT) scan, x-rays and other tests may be done to assess the extent of the spread of ALL and the patient’s general health.
Genetic tests on blood and bone marrow samples will identify the genetic variations of the cancer cells.
Immunotyping, which identifies the exact ALL type, is important as treatment may be slightly different for each type.
Polymerase chain reaction (PCR) helps diagnosis and monitors the response to treatment. Lymph node biopsy will establish the extent of the spread of ALL.
If it is suspected that ALL has spread to the nervous system, a lumbar puncture is done. This involves inserting a needle in the back to remove a sample of cerebrospinal fluid to look for cancer cells.
Management of ALL
There are three phases in the treatment of ALL.
The objective of the initial induction phase is to destroy the ALL cells in the bone marrow and restore balance of the cells in the blood stream.
This is followed by the consolidation phase, which objective is to destroy any remaining ALL cells, particularly in the central nervous system.
The objective of the subsequent maintenance phase is to prevent a recurrence of ALL.
The treatments include chemotherapy, radiotherapy, other medicines or stem cell transplant.
Chemotherapy is the primary form of treatment in the induction phase.
The chemotherapeutics destroy the leukaemia cells in the bloodstream and bone marrow. A combination of chemotherapeutics would be used in the hospital. They are injected into a thin tube in a blood vessel in the arm or close to the heart.
Some chemotherapeutics are injected through a thin tube placed in the spine to combat ALL cells that may have spread to the nervous system and brain.
Side effects are common and temporary. They include nausea, vomiting, diarrhoea, mouth ulcers, loss of appetite and hair and infertility, which may be temporary or permanent.
Corticosteroids may be given by injection or orally to improve the effectiveness of chemotherapeutics.
Regular blood transfusions are usually required as well as a clean environment due to the increased risk of infection, which is promptly treated if it occurs.
Treatment in the consolidation phase, which lasts several months, involves regular injections of chemotherapeutics, usually on an out-patient basis.
However, hospitalisation may be required if symptoms worsen or infection(s) occur.
Treatment in the maintenance phase involves regular chemotherapeutic tablets and regular monitoring of the effectiveness of treatment.
There are specific medicines to treat Philadelphia chromosome-positive ALL.
Radiotherapy with high doses of radiation is done if the leukaemia cells have spread to the nervous system or brain, and/or to prepare for stem cell transplant.
Side effects are common and usually temporary. They include nausea, tiredness, hair loss, restricted pubertal growth and cataracts.
A stem cell transplant may be considered if chemotherapy is ineffective. The transplant helps re-establish healthy stem cells by placing healthy leukaemia-free stem cells in the bone marrow.
Prior to a stem cell transplant, high dose chemotherapy and radiotherapy is given to destroy the leukaemia-producing bone marrow.
Subsequently, infusions from a compatible donor are given through a tube in a vein. The ideal donor of stem cells is a sibling.
Some ALL patients may enrol in clinical trials involving experimental treatments or new combinations of known treatments.
There is no guarantee that the trial will be more effective than current treatments. Discussion with the attending doctors about the benefits and risks is advisable.
Learning about ALL in the shortest possible time to make care decisions and reliance on the attending doctors, family and friends would be helpful.
Dr Milton Lum is a past President of the Federation of Private Medical Practitioners Associations, Malaysia and the Malaysian Medical Association. The views expressed do not represent that of any organisation the writer is associated with. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.