Acute myeloid leukaemia (AML) is a blood cancer of the bone marrow’s myeloid cells. Acute leukaemias are so called because they develop rapidly and are aggressive types of leukaemia. This is in contrast to chronic leukaemias which develop, and usually progress, slowly.
Classification of AML
AML is divided into four groups according to the 2016 World Health Organisation (WHO) Classification of Tumours of Haematopoietic and Lymphoid Tissues:
- AML with genetic abnormalities: 40% – 50%
- AML with myelodysplasia related changes: 24% – 35%
- AML due to prior treatment with chemotherapy/radiation: 10%
- AML, not otherwise specified (cases of AML that do not fit into the above three groups)
The WHO classification is based on the appearance of the AML cells under the microscope, as well as information of the specific genetic changes in the AML cells.
Sandra is an AML patient. You can watch her story above.
What causes AML?
In most cases of AML there is no obvious cause but it is important to understand that:
- It is not a condition which can be caught from someone else (contagious)
- It is not passed on from a parent to a child (inherited)
- Age – like most forms of cancer AML is more common in older people
- Being male – AML affects slightly more males more than females
- Genes – In the vast majority of cases AML does not run in families. There have been very rare cases of families where AML affects more than one generation. This is very rare and, in almost all cases, there is no cause for anxiety or for screening tests
- Environment – Although most cases do not have an apparent cause there are some factors such as some chemicals and high levels of radiation which may increase the chance of developing leukaemia. The most common chemical cause is smoking, which is thought to cause about one in four cases.
- Other bone marrow diseases – Some cases of AML affect people who already have a bone marrow disease. The bone marrow diseases most often associated in this way are myelodysplastic syndrome (MDS) and the myeloproliferative neoplasms (MPN).
Signs and symptoms of AML
Early signs and symptoms of AML are a result of the leukaemia cells in the bone marrow which cause anaemia (low levels of red blood cells), thrombocytopenia (low levels of platelets), and an increased number of infection due to decreases in white cell counts. Symptoms also include:
- Pale appearance
- Weakness or feeling tired
- Shortness of breath
- Easy bruising or bleeding
- Petechiae which are flat, pinpoint spots under the skin caused by bleeding
- Loss of weight or appetite
- Frequent minor infection
Involvement of AML outside the bone marrow has been described in less than 10% of adult patients and occurs in sites such as the spleen, lymph nodes, and the brain.
Video: Professor Mary Frances McMullin discusses testing in Acute Myeloid Leukaemia (AML)
For the majority of patients, a diagnosis of AML can be made on the basis of examining a blood and bone marrow sample. Chromosome analysis and immunophenotyping analysis are only specific for AML with genetic abnormalities, but they do enable the diagnosis of other types of AML to be confirmed in difficult cases.
Chromosome and immunophenotyping analyses can also help to classify patients with AML as having a low, intermediate or high risk of relapse which will impact on their choice of treatments.
The following tests are used to reach a diagnosis of AML:
Bone and marrow sample analysis
Using the patient’s blood sample, a full count of the number of red cells, white cells and platelets is carried out, including a breakdown of the different white cell types to determine which white cells are involved.
An examination of a bone marrow sample is the most important test for diagnosing AML. A sample of bone marrow is taken from the hip bone, generally under local anaesthesia, and examined to determine the number and type of cells present and if they are developing normally. In AML, the white blood cell count is higher than normal. Immature leukaemia cells, which are slightly larger than normal white blood cells, are seen in the blood as well as the bone marrow. A diagnosis of AML normally requires seeing at least 20% of immature leukaemia cells in the blood and bone marrow. The white blood cell involved will be specific for the type of AML.
In the case of AML with genetic abnormalities, AML can be diagnosed if the patient has certain chromosome abnormalities even if their leukaemia cell count is less than20%.
Blood tests and bone marrow samples will be repeated throughout treatment to monitor response to treatment.
Immunophenotyping is a method used to count the number of leukaemia cells present in the patient’s blood and bone marrow. In the laboratory, specific antibodies to the antigens on the leukaemia cells are developed and tagged with fluorescent markers. When mixed with the patient’s blood sample, the antibodies attach themselves to the antigens on the leukaemia cells.
Immunophenotyping is routinely performed by flow cytometry which processes blood and bone marrow fluid and counts the number of cells with the tagged antibodies attached to the leukaemia cells. The flow cytometer rapidly measures the number and size of the thousands of blood cells. This enables a rapid count of the number of leukaemia cells as a proportion to normal cells.
The study of abnormalities in the chromosomes and genes of patients with AML is important not only to establish or assist the diagnosis, but also for the classification of AML and the risk of the AML to patients.
AML is one of the first malignancies where the molecular mutations leading to the development of AML has been extensively studied. Next generation sequence analysis has become part of the standard diagnostic process which can lead to the use of targeted treatments against these mutations but also provides specific information on risk grouping and prognosis.
An important part of classifying the types of AML is to allow the different kinds of AML to be grouped into three risk groups: high, intermediate and low risk of the patient relapsing.
For example, patients with low-risk AML have a good chance of being cured and a low risk of relapse, whereas patients with high-risk AML have a high risk of relapse and need to undergo intensive treatments.
Risk classification is based mainly on the chromosome/gene analysis.
A patient’s risk group can change during treatment, but your medical team will be able to provide updates relating to your condition.
Other tests for patients with AML include:
- Lumbar puncture – A needle is inserted into the spinal canal to access the area around the spinal cord and draw off a small amount of cerebral spinal fluid (fluid that surrounds the brain and spinal cord) to determine if any leukaemia cells are present. Special treatment will be required to remove these leukaemia cells.
- Imaging – X-rays, ultrasound or scans are used to access and monitor the impact of the AML on the organs of the body. Computed tomography (CT) scans and magnetic resonance imaging (MRI) are used where appropriate.
Staging not used for AML, because it is spread throughout the body when first diagnosed. There is a system to classify AML as high-risk, standard or low-risk. It is important to stress that this refers to the chance of a good response following standard treatment. If treatment is selected according to risk group, many patients with high-risk disease will do very well. It is also, unfortunately, not always true that a patient with good risk disease will do well. The risk group is only of the factors which affects the outcome of treatment.
Treatment of AML
Because AML progresses rapidly, virtually all patients with AML start treatment as soon as possible after diagnosis.
Overview of treatment
The main aim for the treatment of AML is to achieve and maintain complete remission. Complete remission is defined as less than5% of leukaemia cells in the bone marrow and recovery of blood cell counts to normal.
Standard treatment of AML remains intensive induction chemotherapy to remove the majority of the leukaemia cells in the blood and bone marrow. This is followed by a consolidation phase with either further chemotherapy or an allogeneic stem-cell transplant (allo-SCT) to destroy any remaining leukaemia cells in the body and prevent a relapse.
Most patients with AML will receive the combination of anthracycline chemotherapy drugs and the chemotherapy drug cytarabine to which a targeted drug may be added if required. The exception to this is APL, which should not be treated with chemotherapy as this can lead to severe bleeding. APL does not respond to chemotherapy, but can achieve very good results if treated with the differentiating agents all-trans retinoic acid and arsenic trioxide.
A targeted drug is a drug that is designed to specifically interrupt the leukaemia cells from growing in the body without simultaneously harming healthy cells the way conventional chemotherapy drugs do.
The use of maintenance therapy in AML is controversial. However, if it is deemed necessary, patients usually receive the same therapy as used during induction. For patients who cannot withstand intensive chemotherapy, low-intensity treatment with low-dose cytarabine or therapy with hydroxycarbamide (also called hydroxyurea) is often beneficial and generally well-tolerated.
Despite the introduction of new targeted drugs such as FLT3 inhibitors, a number of patients with AML will still have to undergo an allo-SCT.
Standard induction therapy generally consists of a continuous infusion of cytarabine for seven days, combined with an anthracycline drug (daunorubicin or idarubicin) for three days.
The drug Vyxeos contains cytarabine and daunorubicin combined in tiny fat droplets called liposomes. The liposomes protect the drugs from being broken down early, so they remain in the body longer than if cytarabine and daunorubicin were given as separate infusions. It is also thought that the liposomes build up in the bone marrow to enhance their effect in leukaemia cells.
Vyxeos is approved for the treatment of adults with newly diagnosed AML and has also been recommended by NICE for patients with untreated AML who have secondary AML or AML with myelodysplasia-related features. Alternatively, gemtuzumab ozogamicin is a newly NICE approved monoclonal antibody (anti-CD33) administered for three days that can be given in combination with a continuous infusion of cytarabine for seven days, combined with an anthracycline drug (daunorubicin or idarubicin) for three days to all newly diagnosed patients with AML except patients who are high risk.
Finally, midostaurin is the only flt-3 inhibitor which is given after the continuous infusion of cytarabine for seven days combined with an anthracycline drug (daunorubicin or idarubicin) for three days (starts on day eight). This is for patients with the flt-3 ITD mutation positive AML and has significantly improved the survival for this group of AML patients.
If patients with AML do not achieve remission, induction therapy can be repeated, or a different chemotherapy drug can be tried. Several studies to improve the complete remission rate in patients have tried using different anthracycline drugs, higher doses of cytarabine, or adding in other drugs such
as etoposide, fludarabine, or cladribine. However, there is no conclusive evidence that any of these options are any more effective than the cytarabine and daunorubicin combination.
Consolidation therapy is used to eradicate any remaining leukaemia cells in the body, which is also called minimum residual disease (MRD). Consolidation
therapy lessens the risk for relapse and increases patient survival. It can be used to achieve a cure or as bridge treatment to an allo-SCT. Conventional consolidation therapy includes intensive chemotherapy including a targeted drug followed by an allo-SCT.
Consolidation therapy with further chemotherapy, often with higher doses of the same drugs used for induction therapy, will depend on:
- Patient’s age
- Their physical fitness
- Detection of any chromosomal abnormalities which are linked with a likelihood of relapse
Patients with low-risk AML can undergo further consolidation chemotherapy, whereas those with intermediate-risk AML should undergo either chemotherapy or an allo-SCT and those with high-risk AML are recommended for an allo-SCT.
For young patients (aged 18 to 60/65 years old), the following treatments are recommended according to their AML risk:
- Low-risk: Two to four cycles of intermediate-dose cytarabine.
- Intermediate-risk: Two to four cycles of intermediate-dose cytarabine, with or without an allo-SCT depending on the chromosome abnormalities.
- High-risk: An allo-SCT using a related or unrelated donor.
For older patients (aged over 60/65 years old), the following treatments are recommended according to their AML risk:
- Low-risk: Two to three cycles of low-dose cytarabine.
- Intermediate to high-risk: No value was found with consolidation therapy. An allo-SCT or new drugs being tested in clinical trials should be considered.
For patients who cannot tolerate any of the treatments for AML, or who do not wish any treatment, the best supportive care can be achieved with hydroxycarbamide. This is a drug that prevents cell division with the aim of lowering the white blood cell count. This helps relieve pain which can be caused by a high white blood cell count.
Allogeneic stem cell transplantation
In younger patients, who are more likely to withstand the rigours of bone marrow transplantation, an allo-SCT can be performed. An allo-SCT is the transplantation of bone marrow stem cells from a matching donor such as a sibling, parent or child. The allo-SCT helps re-establish a healthy bone marrow.
Patients are given high doses of chemotherapy to destroy any cancerous cells, and then healthy cells from the donor are transplanted into the recipient.
An allo-SCT is known to reduce the risk of relapse of the leukaemia more than chemotherapy, but it is also associated with serious complications, including an increased risk of death. For this reason, allo-SCTs tend only to be used in patients who have a greater risk of relapse.
Central nervous system treatment
In patients where leukaemia cells have spread to the brain and spinal cord, chemotherapy may be injected directly into the cerebrospinal fluid to kill any remaining leukaemia cells.
Cytarabine 40mg to 50mg can be administered into the cerebrospinal fluid, two to three times per week until all the leukaemia cells have been removed, and then followed by three further injections at the same dosage. Alternatively, cytarabine 50mg can be given every other week for approximately six cycles in special situations, for example if the patient has very high levels of white blood cells.
Radiation therapy of the brain and spinal cord can also be performed. Radiation therapy consists of irradiation of the brain and spinal cord with high doses of X-rays or proton beams. Radiation therapy of the brain is often restricted to the 5% of patients who persistently show leukaemia cells in the body.
Treatment of older and frail patients with AML
For older patients (aged over 65 years old), the best treatment strategies are still under discussion as elderly patients with AML tend to have high-risk
AML, are less probable to have a good response to chemotherapy, and often suffer more side effects with the currently established treatments.
Older and frail patients cannot tolerate intensive induction or consolidation chemotherapies. Alternative treatments available for them include low-intensity treatments such as low-dose cytarabine or hypomethylating agents such as decitabine and azacitidine. Hypomethylating agents inhibit the enzyme DNA methyltransferase which is vital for cell development. Azacitidine is approved for the treatment of AML patients with 20% to 30% of leukaemia cells in the blood and bone marrow. Decitabine is approved specifically for the treatment of adult patients with AML who are not suitable for standard induction chemotherapy.
Both azacitidine and decitabine may help induce remission and control the progression of AML for a while. Treatment with these drugs can be given as required and it is not divided into induction and consolidation treatment.
Patients with heart disease cannot be treated with anthracyclines. Additionally, some chemotherapy drugs can have cardiovascular side effects which worsen existing heart disease.
These chemotherapy drugs include mitoxantrone and arsenic trioxide. Therefore, patients with heart disease are often given different chemotherapy drugs.
Treatment of refractory or relapsed AML
Despite ongoing improvements of the treatment of patients with newly diagnosed AML, up to 45% of patients will not achieve remission. In addition, of the patients who do achieve a first complete remission, between 30%(younger patients with low-risk AML) and 80% (older patients with high-risk AML) may relapse.
For patients whose AML has returned (relapsed AML) or for those who did not respond to induction therapy (refractory AML), re-induction therapy can be given. Re-induction therapy can be the same as induction therapy or a different chemotherapy drug can be tried.
In patients with a low risk of relapse, successive cycles of chemotherapy alone is usual, and in patients with a high risk of relapse, an allo-SCT is typically recommended.
Supportive care does not include active treatment, but endeavours to maintain a quality of life. It concentrates on treating any symptoms or complications that arise so that the patient is as comfortable as possible.
Supportive treatment consists of blood and platelet transfusions and administration of hydroxycarbamide. Induction treatment destroys leukaemia cells, but also most of the normal bone marrow cells; therefore, patients may need antibiotics if they develop infections.
Questions to ask your doctor about AML
Questions to ask your doctor about AML
We understand going through a blood cancer journey can be difficult. It may help to talk to a close friend or relative about how you are feeling. Here are some questions that may be useful to ask your doctor.
- How would I know if I had AML?
- What tests will I need to have?
- What will the tests show?
- How long will the results take?
- How rare is AML?
- What sort of treatment will I need?
- How long will my treatment last?
- What will the side effects be?
- Is there anything I should or shouldn’t eat?
- Will I be able to go back to work?
- Where can I get help with claiming benefits and grants?
- Where can I get help dealing with my feelings?
We have free patient information available for AML patients.
You can download the booklets on our information pages here.
Alternatively, you can have the information delivered free of charge by requesting it through our resources page.
Support for AML patients
There is also a general leukaemia support group on Facebook which is ran by Leukaemia Care. To request to join, click here.
Offline support groups
There area number of haematology support groups in the UK. Find out more on our support groups page.
Acute Leukemia Advocates Network (ALAN)
ALAN is an independent global network of patient organisations, dedicated to changing outcomes of patients with acute leukemias. It aims to build capacity in the members of the network to deliver tailored services to acute leukemia patients and carers on the national level, while joining forces between organisations on the policy and research level across countries.
Published: April 2020
Review date: April 2022