Acute myeloid leukaemia

Overview: What Is Acute Myeloid Leukaemia?

Acute myeloid leukaemia (AML) is an aggressive cancer of the blood and bone marrow — the spongy tissue inside bones where all blood cells are produced. It is the most common type of acute leukaemia in adults and one of the most rapidly progressing forms of blood cancer.

The word “leukaemia” literally means “white blood,” referring to the flood of abnormal white blood cells seen in patients. The term “myeloid” describes the specific family of blood cells affected. In healthy bone marrow, immature cells called myeloid stem cells mature into:

• Red blood cells – carry oxygen around the body
• White blood cells (such as neutrophils and monocytes) – fight infection
• Platelets – help the blood clot and stop bleeding

In AML, a single immature myeloid cell acquires genetic damage (mutations) and begins to multiply uncontrollably. These cancerous, immature cells are called blast cells or “leukaemic blasts.” They never develop into functioning blood cells. Instead, they accumulate rapidly in the bone marrow and bloodstream, crowding out normal, healthy blood cell production. The word “acute” refers to this speed: without treatment, AML typically progresses within weeks to months.

AML accounts for approximately 1% of all cancers worldwide, but it causes a disproportionately high number of cancer deaths due to its aggressive nature. It can occur at any age, including in children, but risk rises sharply with age — the median age at diagnosis is around 68 years.

What Happens Inside the Body? (How AML Develops)

Understanding AML begins with a single altered cell:

1. DNA damage occurs. A myeloid stem cell in the bone marrow acquires mutations in genes that normally control cell growth, division, and maturation (for example, FLT3, NPM1, CEBPA, DNMT3A, or TP53).
2. Maturation is blocked. Instead of developing into a working blood cell, the cell becomes “stuck” at an immature stage — a blast cell.
3. Uncontrolled multiplication. The blast cells clone themselves repeatedly, overwhelming the bone marrow.
4. Normal blood production is suppressed. With the marrow full of blasts, production of healthy red cells, white cells, and platelets collapses.
5. Blasts spill into the bloodstream and may infiltrate other organs, including the gums, skin, liver, spleen, and (less commonly) the brain and spinal cord.

Almost every symptom of AML — from tiredness to infections to bruising — can be traced back to this single mechanism: the bone marrow can no longer make enough healthy blood cells.

Types and Classification of AML

AML is not a single disease but a family of related diseases, distinguished by which cell type is affected and which genetic abnormalities are present. Correct classification matters enormously because it guides treatment and predicts outcomes.

The older FAB (French-American-British) system divides AML into subtypes M0 to M7 based on the appearance of the cells under the microscope. Modern classification systems (WHO and ICC) now rely mainly on genetic and molecular findings.

Doctors also assign patients to risk groups (favourable, intermediate, or adverse) under systems such as the European LeukemiaNet (ELN) classification, based on cytogenetics (chromosome analysis) and mutation testing. This risk score directly determines whether a patient is offered standard chemotherapy, targeted drugs, or a stem cell transplant.

Causes and Risk Factors

In most people with AML, no single cause is ever identified. The disease arises from acquired (not inherited) DNA damage in bone marrow cells. However, several factors are known to increase risk:

Established risk factors

• Older age – risk rises steeply after age 60
• Previous cancer treatment – certain chemotherapy drugs (alkylating agents, topoisomerase II inhibitors) and prior radiotherapy
• Pre-existing blood disorders – especially myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (e.g., myelofibrosis, polycythaemia vera); about one in three MDS patients eventually develops AML
• Chemical exposure – long-term exposure to benzene (found in cigarette smoke, petrol, and some industrial solvents)
• Smoking – the only confirmed lifestyle risk factor
• High-dose radiation – e.g., survivors of atomic bomb exposure or nuclear accidents
• Inherited genetic conditions – Down syndrome, Fanconi anaemia, Li-Fraumeni syndrome, neurofibromatosis type 1, and certain inherited mutation syndromes (e.g., germline CEBPA, RUNX1, or DDX41 mutations)
• Being male – AML is slightly more common in men than women

Important: AML is not contagious, is not caused by injury or stress, and in most cases is not passed down through families.

How Does AML Look?

This section describes how AML actually appears — in the patient, on the skin, in the mouth, and under the microscope — helping readers and clinicians visualise what doctors look for.

On the outside: how a person with AML may look

Because the bone marrow fails, the visible appearance of AML reflects the shortage of each blood cell type:

• Pale, greyish, or washed-out skin and inner eyelids – a sign of severe anaemia (too few red blood cells)
• Exhausted appearance – patients often look profoundly tired and may be breathless after minor effort
• Pinpoint red or purple spots on the skin (petechiae) – tiny bleeds under the skin caused by very low platelets; often seen on the legs, ankles, and inside the mouth
• Large, unexplained bruises (ecchymoses) – purplish patches appearing with minimal or no trauma
• Bleeding gums or frequent nosebleeds
• Swollen, spongy, overgrown gums (gum hyperplasia) – particularly characteristic of the monocytic subtypes of AML, where leukaemic cells infiltrate the gum tissue
• Skin lumps or rashes (leukaemia cutis) – firm, raised, flesh-coloured to violaceous nodules or plaques caused by leukaemic cells invading the skin
• Signs of infection – feverish, flushed appearance; mouth ulcers; sore throat; or skin infections that fail to heal

On physical examination

A doctor may find:

• Enlarged liver (hepatomegaly) and spleen (splenomegaly), felt as fullness under the ribs
• Occasionally enlarged lymph nodes (less common than in lymphoblastic leukaemia)
• Bone or sternal tenderness caused by the marrow being packed with leukaemic cells
• In acute promyelocytic leukaemia: widespread abnormal bleeding and clotting (disseminated intravascular coagulation, DIC)

Under the microscope: how the cells look

• The blood film shows large numbers of blast cells — big, immature cells with large nuclei and scant cytoplasm, which are normally absent from circulating blood.
• A hallmark feature is the Auer rod — a slender, pink-red, needle-shaped structure inside blast cells, formed from crystallised granules. Auer rods are diagnostic of myeloid leukaemia and are especially numerous in APL.
• The bone marrow biopsy is characteristically hypercellular (overcrowded), with normal fat and blood-forming tissue replaced by sheets of blasts. By definition, AML is usually diagnosed when blasts make up ≥20% of marrow or blood cells — or at any percentage if certain defining genetic abnormalities are present.
• Blood counts typically show the classic picture: low haemoglobin, low platelets, and abnormal white cell counts (often very high, but sometimes paradoxically low).

Symptoms of AML

Symptoms usually develop quickly, over days or weeks, which distinguishes acute leukaemia from slower, chronic forms. They arise from bone marrow failure and, occasionally, from infiltration of tissues by leukaemic cells.

Most common symptoms

• Persistent fatigue and weakness – often the earliest and most noticeable complaint (anaemia)
• Pale skin
• Shortness of breath, especially on exertion
• Frequent or persistent infections – sore throat, chest infections, urinary infections, mouth infections that do not resolve (due to lack of functioning white blood cells)
• Fever (≥38 °C), sometimes with no identifiable source
• Easy bruising or bleeding – nosebleeds, bleeding gums, blood in urine or stool, heavy menstrual periods
• Petechiae – flat, pinpoint red spots on the skin
• Unintentional weight loss
• Loss of appetite
• Night sweats
• Bone or joint pain – caused by marrow expansion; more common in children

Less common symptoms

• Swollen or bleeding gums and mouth ulcers
• Skin nodules or rashes (leukaemia cutis)
• Abdominal discomfort or fullness from an enlarged spleen/liver
• Headache, visual disturbances, or confusion — rare, but possible with very high blast counts (leukostasis) or nervous system involvement

⚠️ Seek emergency care immediately if you experience uncontrolled bleeding, a high fever with known low blood counts, sudden severe headache, confusion, or difficulty breathing.

How Is AML Diagnosed?

Because AML progresses rapidly, diagnosis is treated as a medical priority. The work-up typically includes:

Treatment of AML

Treatment must usually begin quickly, often within days of diagnosis. The approach depends on the AML subtype, genetic risk group, the patient’s age, and overall fitness.

Phase 1 – Remission induction

The goal is to destroy leukaemic cells and achieve complete remission (fewer than 5% blasts, with recovery of normal blood counts).

• Standard “7+3” chemotherapy: 7 days of continuous cytarabine plus 3 days of an anthracycline (e.g., daunorubicin or idarubicin) — the backbone of treatment for fit patients for decades.
• CPX-351 (a liposomal combination of cytarabine + daunorubicin) for therapy-related or MDS-related AML.
• Antibiotic, antifungal, and transfusion support is essential, as treatment temporarily wipes out all blood cells.

Phase 2 – Consolidation (post-remission therapy)

Without further treatment, AML almost always relapses. Options include:

• Further cycles of high-dose cytarabine
• Allogeneic stem cell (bone marrow) transplant — replacing the patient’s marrow with a donor’s; offers the best chance of cure for intermediate- and high-risk disease but carries significant risks

Targeted and low-intensity therapies

A major recent advance: patients who are older or unfit for intensive chemotherapy can now be treated with:

Relapsed or refractory AML

Options include salvage chemotherapy, newer targeted drugs, clinical trials, and transplant where feasible. Doctors strongly encourage trial participation, as this remains an area of active research.

Prognosis: What Are the Outlook and Survival Rates?

Prognosis in AML varies more than in almost any other cancer, depending on:

• Age (younger patients do substantially better)
• Cytogenetic and molecular risk group
• Whether the AML is primary or secondary (after MDS or prior chemotherapy)
• Response to the first cycle of treatment (measurable residual disease, MRD, is increasingly used to guide decisions)
• General health and fitness

Approximate figures (population averages; individual outcomes differ):

• Overall 5-year survival is around 30% in adults.
• In patients under 60, survival approaches 40–50% in many centres.
• APL has a cure rate above 90% with modern therapy.
• In patients over 75, historically only 5–10% survived long term, though newer venetoclax-based regimens have significantly improved outcomes.

Living with AML and Supportive Care

Treatment for AML is intensive, and supportive care is a core part of management:

• Infection prevention – prompt reporting of fevers; prophylactic antibiotics/antifungals; hand hygiene
• Blood and platelet transfusions to prevent anaemia symptoms and bleeding
• Nutrition and physical activity as tolerated, under guidance
• Psychological support – a leukaemia diagnosis is life-changing; counselling, support groups, and specialist nurses play a vital role
• Fertility discussions before treatment, as chemotherapy and transplant can affect fertility
• Vaccinations (non-live) and review of medication during remission phases

When to See a Doctor

Book an urgent appointment if you experience any combination of the following lasting more than a couple of weeks:

• Unexplained, persistent fatigue or pallor
• Recurrent infections or fevers
• Unusual bruising, bleeding, or pinpoint skin spots
• Unexplained weight loss, night sweats, or bone pain
• Persistently swollen gums or non-healing mouth lesions

A simple blood test can often provide the first answers within hours.

Key Points to Remember

• AML is a fast-growing cancer of the blood-forming cells in the bone marrow.
• It typically presents with fatigue, infections, bruising, and bleeding over a short period.
• Diagnosis requires blood tests and a bone marrow examination, plus genetic testing to guide therapy.
• Treatment ranges from intensive chemotherapy and stem cell transplant to modern targeted drugs, and outcomes have improved markedly in recent years.
• Acute promyelocytic leukaemia (APL) is a distinct, highly curable subtype — but also a medical emergency due to bleeding risk.
• Anyone with suspicious symptoms should seek prompt medical assessment.

References

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