Acute myeloid leukaemia (AML) is a rare but aggressive blood cancer that develops rapidly in the bone marrow, disrupting the normal production of blood cells and requiring urgent medical attention to prevent life-threatening complications.

Understanding Acute Myeloid Leukaemia

Acute myeloid leukaemia is a type of cancer that affects the blood and bone marrow, which is the soft, spongy tissue found in the centre of most bones. The bone marrow acts like an efficient production line, creating blood cells that your body needs to function properly. It produces stem cells, which are immature cells that develop into red blood cells that carry oxygen, white blood cells that protect against infection, and platelets that help blood to clot.^[2]

In AML, something goes wrong with this production process. The bone marrow begins producing abnormal immature white blood cells called myeloblasts or myeloid blasts. These abnormal cells do not mature into healthy, functioning white blood cells. Instead, they multiply rapidly and crowd out the healthy blood cells in the bone marrow and bloodstream. As these cancerous cells take up more space, there is less room for healthy red blood cells, white blood cells, and platelets. This leads to a cascade of problems throughout the body, including easy bleeding, anaemia (low red blood cell count), and increased vulnerability to infections.^[5]

The word “acute” in the name tells us something important about this cancer. Unlike chronic forms of leukaemia that develop slowly over months or years, acute myeloid leukaemia progresses quickly. If left untreated, it can become life-threatening within weeks or months. This rapid progression means that treatment typically needs to begin soon after diagnosis, often within just a few days.^[4]

AML is also known by several other names, including acute myelogenous leukaemia, acute myeloblastic leukaemia, acute granulocytic leukaemia, and acute nonlymphocytic leukaemia. Despite these different names, they all refer to the same condition. The leukaemia cells can sometimes spread beyond the blood and bone marrow to other parts of the body, including the central nervous system (brain and spinal cord), skin, and gums. In some cases, leukaemia cells can form a solid tumour called a myeloid sarcoma, which may also be called an extramedullary myeloid tumour, granulocytic sarcoma, or chloroma.^[5]

Epidemiology

Acute myeloid leukaemia is considered a rare form of cancer. In adults, it affects approximately 4 in every 100,000 people each year. Among children, the numbers are even lower, with about 1,160 children receiving an AML diagnosis annually. Despite being rare overall, AML is actually the most common type of acute leukaemia diagnosed in adults.^[2][4]

The disease shows a clear pattern when it comes to age. AML typically affects older adults, with most cases diagnosed in people aged 60 and older. However, this does not mean younger adults and children are immune. The condition can and does occur in younger age groups, though less frequently. The risk of developing AML increases significantly with advancing age, making it primarily a disease of the elderly population.^[2]

While AML can affect anyone regardless of background, certain demographic patterns have been observed. The disease can develop in both men and women, and it occurs across all ethnic and racial groups. However, the incidence rates and outcomes can vary based on multiple factors including access to healthcare, underlying health conditions, and genetic factors that may be more common in certain populations.^[3]

Causes

The exact cause of acute myeloid leukaemia remains unclear, and scientists continue to study what triggers this disease. What researchers do understand is that AML develops when certain genes or chromosomes undergo mutations or changes. These genetic alterations create abnormal blood cells that multiply uncontrollably. The process by which normal bone marrow cells transform into cancerous cells is complex and can happen through several different pathways.^[2]

These genetic changes can occur in different ways. Sometimes the mutations happen during a person’s lifetime when something damages or alters their DNA. This could be due to exposure to harmful substances or simply random errors that occur when cells divide. In other cases, a person might inherit a genetic disorder that increases their risk of developing AML. There can also be changes in certain genes present in biological parents’ sperm or egg cells that get passed on to their children.^[2]

In the specific subtype known as acute promyelocytic leukaemia (APL), scientists have identified a particular genetic change that drives the disease. This leukaemia occurs when genes on chromosome 15 switch places with genes on chromosome 17, creating an abnormal fusion gene. This specific chromosomal rearrangement is characteristic of APL and helps doctors identify this particular subtype of AML.^[5]

It is important to understand that AML is not an infectious disease. Unlike a cold or flu, you cannot catch leukaemia from another person through close contact, sharing food, or any other form of transmission. The genetic changes that cause AML occur within an individual’s own cells and are not contagious.^[2]

Risk Factors

While the exact cause of AML remains unknown, researchers have identified several factors that can increase a person’s risk of developing this cancer. Understanding these risk factors does not mean that everyone with these characteristics will develop AML, but rather that their chances are higher compared to people without these risk factors.

Smoking tobacco is one significant risk factor for acute myeloid leukaemia. The harmful chemicals in cigarettes can damage DNA in blood cells, potentially leading to the genetic changes that cause AML. This makes smoking cessation an important preventive measure, not just for lung and heart health, but also for reducing cancer risk.^[5]

Previous cancer treatment can paradoxically increase the risk of developing AML later. People who have received chemotherapy or radiation therapy for another type of cancer may have an elevated risk of developing AML months or years after their initial treatment. This is sometimes called treatment-related or therapy-related AML. The very treatments that saved someone’s life from one cancer can, in rare cases, contribute to the development of another cancer later.^[5]

Exposure to radiation, whether from medical treatments or environmental sources, can increase AML risk. This includes high-dose radiation exposure such as that experienced by survivors of nuclear accidents or atomic bomb exposure. Even medical radiation, while carefully controlled and necessary for diagnosis or treatment, carries a small associated risk.^[5]

Pre-existing blood disorders can also increase the likelihood of developing AML. People who have been diagnosed with conditions such as myelodysplastic syndromes (MDS) or other blood and bone marrow disorders may have a higher risk of their condition progressing to acute myeloid leukaemia. These pre-existing conditions suggest that the bone marrow is already not functioning properly, making the transition to leukaemia more likely.^[14]

Inherited genetic disorders can play a role as well. Certain genetic conditions that people are born with can predispose them to developing AML. These inherited disorders affect how cells grow and divide, making genetic mutations more likely to occur. Age itself is a significant risk factor, with the disease being much more common in people over 60 years old. As we age, our cells accumulate more DNA damage over time, and our body’s ability to repair that damage decreases, making cancer more likely.^[2]

Symptoms

The symptoms of acute myeloid leukaemia can be confusing at first because they often feel similar to having a cold or flu that simply will not go away. In the early stages, people might dismiss their symptoms as a common illness or attribute them to stress or being run down. However, because AML is an aggressive cancer that develops quickly, symptoms tend to become more noticeable and severe as the disease progresses.^[2]

One of the most common symptoms is extreme fatigue that does not improve with rest. This exhaustion occurs because the leukaemia interferes with the production of red blood cells, leading to anaemia. Without enough red blood cells to carry oxygen throughout the body, people feel constantly tired and weak. Along with fatigue, many people experience dizziness and shortness of breath, particularly during physical activity, as their body struggles to get enough oxygen to tissues and organs.^[2]

Unusual bleeding and bruising are hallmark symptoms of AML. People may notice that they bruise very easily from minor bumps that would not normally leave a mark. They might experience frequent nosebleeds, bleeding gums, or find that small cuts take much longer to stop bleeding than usual. Women may notice unusually heavy menstrual periods. These bleeding problems occur because AML reduces the number of platelets in the blood, and platelets are essential for blood clotting. Some people may also notice tiny red spots on their skin called petechiae, which are actually small areas of bleeding under the skin.^[2][4]

Infections become more frequent and harder to shake off. Because AML affects white blood cells, which are the body’s primary defence against infection, people become more vulnerable to bacterial, viral, and fungal infections. They might experience repeated infections, or find that common infections that would normally clear up quickly persist for weeks. Fever is common, sometimes without any obvious source of infection. Many people also experience night sweats that can be drenching enough to require changing bed clothes.^[2]

Other symptoms can include bone pain, back pain, or abdominal pain. The bone pain occurs because the bone marrow is packed with leukaemia cells. Abdominal pain or a feeling of fullness might occur if the spleen or liver becomes enlarged. Some people notice swollen lymph nodes, particularly in the neck, armpits, or groin. Loss of appetite and unexplained weight loss are also common, as the body’s energy is diverted to producing abnormal cells.^[2]

People with AML often develop pale skin due to anaemia. Feeling unusually cold is another symptom related to poor circulation and low red blood cell counts. Headaches can occur, particularly if leukaemia cells have spread to the central nervous system. Wounds or sores may heal more slowly than normal or not heal at all.^[2]

Prevention

Preventing acute myeloid leukaemia is challenging because in most cases, the exact cause is unknown and many risk factors cannot be changed. However, there are some steps people can take to potentially reduce their risk or detect problems early.

The most significant preventable risk factor for AML is smoking. Quitting smoking, or never starting in the first place, can reduce your risk of developing this cancer along with numerous other health problems. For people who smoke, stopping at any age provides health benefits. Healthcare providers can offer support and resources for smoking cessation, including medications and counselling that significantly increase the chances of successfully quitting.^[5]

For people who have had previous cancer treatment, being aware of the potential risk of treatment-related AML is important. While this does not mean avoiding necessary cancer treatment, it does mean that survivors of cancer should maintain regular follow-up appointments with their healthcare providers. These appointments allow for monitoring of blood counts and early detection of any concerning changes. If you have received chemotherapy or radiation therapy in the past, make sure your current doctors are aware of this history.^[5]

People with pre-existing blood disorders such as myelodysplastic syndromes should work closely with a haematologist (blood specialist) who can monitor their condition carefully. Regular blood tests can detect changes that might indicate progression toward leukaemia, potentially allowing for earlier intervention.

While these preventive measures may help reduce risk or enable earlier detection, it is crucial to understand that there is no guaranteed way to prevent AML. Many people who develop this disease have no identifiable risk factors and have done nothing “wrong.” The goal is simply to minimize controllable risks where possible while remaining vigilant about any unusual symptoms that warrant medical attention.

Pathophysiology

To understand what goes wrong in acute myeloid leukaemia, it helps to first understand how blood cell production normally works. Healthy bone marrow contains blood stem cells, which are immature cells with the potential to develop into any type of blood cell. These stem cells can become either myeloid stem cells or lymphoid stem cells. Myeloid stem cells go through several stages of development before maturing into red blood cells, certain types of white blood cells (including granulocytes and monocytes), and platelets.^[5]

In AML, genetic mutations disrupt this carefully controlled process of blood cell development. The mutations occur in myeloid stem cells or in cells at early stages of myeloid development. These genetic changes cause the cells to stop maturing properly. Instead of developing into functional blood cells, they remain stuck as immature blasts. These abnormal myeloblasts do not die off naturally the way normal cells do. Instead, they continue to multiply, creating more and more abnormal cells.^[3]

Normal cells in the body follow genetic instructions that tell them when to grow, when to stop growing, and when to die. Think of these instructions like a carefully written recipe that ensures cells behave appropriately. In AML, the genetic mutations damage these instructions. The cells no longer respond properly to signals that would normally tell them to mature, stop dividing, or undergo natural cell death. This loss of normal control mechanisms allows the leukaemia cells to accumulate rapidly.^[2]

As the number of leukaemia cells increases in the bone marrow and blood, they physically crowd out the healthy cells. Imagine the bone marrow as a factory with limited space. When that space becomes filled with non-functional leukaemia cells, there is literally no room left for the production of normal blood cells. This results in ineffective erythropoiesis (poor red blood cell production) and ineffective megakaryopoiesis (poor platelet production). The result is relatively rapid bone marrow failure compared to chronic or slower-growing leukaemias.^[3]

The consequences of this bone marrow failure manifest throughout the body. With fewer red blood cells being produced, tissues and organs do not receive adequate oxygen, causing fatigue, weakness, and shortness of breath. The shortage of healthy white blood cells, particularly mature infection-fighting cells, leaves the body defenceless against bacteria, viruses, and fungi. The lack of platelets means the blood cannot clot properly, leading to easy bruising and bleeding. All these problems develop relatively quickly because AML is an acute, rapidly progressing disease.^[3]

There are several subtypes of AML based on which type of myeloid cell is affected and what specific genetic changes are present. Some subtypes involve cells that normally develop into neutrophils (a type of white blood cell), while others affect cells that produce monocytes (another white blood cell type) or cells that create red blood cells and platelets. Medical pathologists examine cancerous cells under a microscope and look for specific chromosomal changes and gene mutations to determine the exact subtype. This classification is important because different subtypes can behave differently and respond to treatment in different ways.^[2]