Acute lymphoblastic leukaemia (ALL), also known as acute lymphocytic leukaemia, is a type of cancer that causes an overproduction of immature white blood cells, also known as lymphoblasts or leukaemic blasts.
Blood is the bodily fluid of the circulatory system that provides nutrients and oxygen to our tissues, and helps to remove waste from our bodies. There are three primary types of blood cells produced in the inner, spongy portion of the bone (bone marrowsoft, spongy tissue found in bones that makes blood cells) from stem cells (immature blood cells that develop into either red blood cells (RBCs), white blood cells (WBCs), or platelets). RBCs, or erythrocytes, are responsible for providing oxygen to the tissues in our body, as well as transporting carbon dioxide to the lungs to be exhaled. WBCs are responsible for fighting infection and disease in the body. Platelets are blood cells that play a major role in blood clotting (or coagulation), which is an important process that helps reduce blood loss after injury.
ALL causes excess immature WBCs to be produced, which reduces the capacity of the bone marrow to produce RBCs, healthy WBCs, and platelets.
ALL is the most common form of childhood leukaemia. It is more common in males, and is generally diagnosed in children under 14 years of age. However, anyone can develop this disease.
Types of Acute Lymphoblastic Leukaemia
There are several different types of ALL, which are categorised by the types of cells they originate from.
Pre-B-cell ALL
Pre-B cell ALL, also known as precursor B-cell ALL, is the most common type of ALL, and causes excess production of immature (or precursor) B cells (a type of WBC) in the bone marrow. This type of ALL is often aggressive, and may metastasise. In children, the prognosisto predict how a disease/condition may progress and what the outcome might be for this disease is often good when caught early. However, adults with pre-B cell ALL may not have as good of a prognosis.
B-cell ALL
B-cell ALL, also known as Burkitt-like or Burkitt type ALL, is the least common type of ALL that develops from maturing B cells in the bone marrow. This type of ALL is often aggressive, and may metastasise. Both adults and children with this disease can have a good prognosis when caught early.
T-cell ALL
T-cell ALL is a less common type of ALL that develops from developing T-cells (a type of WBC) in the bone marrow. This subtype is often aggressive, and may metastasise. In children, the prognosis for this disease is often good when caught early. However, adults with T-cell ALL may not have as good of a prognosis.
Treatment
Staging and Grading of ALL
When cancers are detected, they are staged and graded based on size, metastasis, and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, because of how rare ALLs are, there is currently no standard staging and grading system for this disease. Instead of staging and grading, your doctor will recommend a treatment plan based on the following factors:
- The type of ALL you have.
- Whether or not the cancer has metastasised.
- Your age.
- General health.
- Your treatment preferences.
Your doctor may also recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Phases of Treatment
Treatment for ALL in both children and adults are generally done in phases:
Phase 1: Remission Induction Therapy
Remission induction therapy is an intensive course of treatment aimed at inducing disease remission. For this phase, the patient is admitted to hospital. In some cases, the disease won’t respond to treatment as expected, and it may be said that the patient has a resistant or refractory disease. In these cases, the doctor may recommend a more intensive form of therapy to treat the disease more effectively.
Phase 2: Post-remission (Consolidation) Therapy
After remission is achieved, post-remission or consolidation therapy is used to help destroy any remaining cancer cells left in the body. This phase is crucial for ensuring the cancer does not return (or relapse), and that it does not spread into the central nervous system (CNS) (the system responsible for all sensory and motor functions in the body that is composed of the brain and the spinal cord). The intensity of this phase depends on how well the patient responds to phase one of treatment.
Phase 3: Maintenance Therapy
Maintenance therapy is the final phase of treatment, and is designed to keep the patient’s disease in remission, and to prevent it from relapsing. This phase generally lasts for several months, and the patient is generally treated as an outpatient; however, in some cases they may need to be admitted into hospital.
Treatment Options
Treatment is dependent on several factors, including age, stage of disease and overall health.
Treatment options for ALLs in both children and adults may include:
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Corticosteroidsa type of anti-inflammatory medication that is used to treat inflammation.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Stem cell transplanta procedure that involves replacing unhealthy blood-forming cells (stem cells) with healthy stem cells.
- Targeted therapymedication that targets specific molecular features of cancer cells.
- Immunotherapya treatment that uses a person's immune system to fight cancer, potentially including CAR T-cell therapya type of immunotherapy where a patients T-cells (a type of white blood cell in the immune system) are re-engineered to target cancer cells; also known as chimeric antigen receptor T-cell therapy.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
While the cause of ALL remains unknown, the following factors may increase the likelihood of developing the disease:
- Genetic mutations of genes involving blood cell development.
- Prior exposure to radiation and/or chemotherapy.
- Being exposed to x-rays before birth.
- Having certain genetic conditions, such as:
- Down syndrome.
- Neurofibromatosis.
- Bloom syndrome.
- Fanconi anaemia.
- Ataxia-telangiectasia.
- Li-Fraumeni syndrome.
- Klinefelter syndrome.
- Exposure to industrial chemicals, potentially including:
- Benzene.
- Pesticides.
- Being exposed to certain viral infections.
- Having an identical twin who develops ALL within the first year of life.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Symptoms
Symptoms of ALL are similar between adult and paediatric subtypes.
In the early stages of disease, some patients may appear symptomatic. As the cancer progresses, some of the following symptoms may appear:
- Anaemiaa condition where there aren't enough red blood cells in the blood, causing fatigue, weakness and pale skin and affecting how the body responds to infection, which carries its own set of symptoms:
- Fatigue.
- Dizziness.
- Paleness.
- Dyspnea.
- Frequent or persistent infections.
- Easy bruising and/or bleeding.
- Bone and/or joint pain.
- Lymphadenopathyswollen lymph nodes/glands, also known as adenopathy in the neck, underarms, stomach, and/or groin.
- Abdominal discomfort, potentially caused by a swollen liver, thymus, and/or spleen.
- Purpuraa rash of small, red dots due to small superficial capillary bleeds; generally larger than petichiae or petechiaea rash of small, red dots due to small superficial capillary bleeds; generally smaller than purpura.
- Unexplainable weight loss and/or loss of appetite.
- Fever and/or drenching night sweats.
- Heavy menstrual periods.
Not everyone with the symptoms above will have cancer, but see your GP if you are concerned.
Diagnosis
If your doctor suspects you have an ALL, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Imaging tests (if the cancer is thought to have spread beyond blood and bone marrow), potentially including:
- X-raya type of medical imaging that uses x-ray beams to create detailed images of the body .
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- Ultrasounda type of medical imaging that uses soundwaves to create detailed images of the body .
- Lumbar puncturea procedure that involves inserting a needle between two vertebrae in the lower spine and extracting a sample of cerebrospinal fluid (CSF) for analysis.
- Bone marrow aspirationa procedure that involves inserting a needle into the hipbone (or the breastbone in some cases) to remove samples of solid and liquid bone marrow.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
